Introduction:

Fist off I would like to say that I am doing this wright up because I have had quite a few people ask me to do it and since there isn't a lot of revshots around and the original wright up is not available anymore  I thought  it would be a good thing to have around. Especially since there is a lot of cheap, safe and good darts that dont hopper that well coming out of china lately i figured a few people might want to build a mag fed homemade again. Secondly  I have to mention that I did not design this blaster, from what I have seen luiec3 is responsible for this blaster . This blaster was purchased from a nerfhaven user (luckydude), although most of the blaster has been re built some of the credit goes to him for building the blaster because it aloud me to study the blaster inside and out,make the changes I thought where necessary and eventually do this wright up. SInce I dont have anything else to reference im going to assume the way I received this blaster was the way they were intended to be. Here is a list the "stock" features and a list of the changes i made. I perceive  them as upgrades but that is just my opinion. The 1.25" Thin wall plunger tube can be substituted with a ERTL PAS plunger tube( witch is even bigger), if you do this use the stock pas plunger head. 

Specs of blaster when recived:

- 1 1/4" pvc plunger tube

- 5" of draw

- brass and cpvc breach going into a  12"petg barrel

- 1 1/2" thinwall pvc pump grip 

- #6-32 hardware 

- rainbow catch 

- omni directional catch 

- U cup+rubber washer seal 

- K26 spring 

Changes made:

- expanded plunger tube using  1-1/4 thin wall pvc (for a even bigger plunger tube a pas PT can be used) 

- 9/16 brass breach with tightening rings ( 14" barrel ) 

- k26+ arrow storm spring 

- spring spacer for more compression 

- stronger catch spring 

- #10-32 bolt for the priming rod 

- Polycarb and delrin angled fore grip added to the pump 

- air release hole in breach for smooth loading 

Matierals needed:

- 1' of 1/2" nylon rod

- 2' of 1.5" thinwallpvc 

- 3' of 1' pvc 

- 5/8" clear thinwall pvc 

- 1"- 1/2" pvc bushing 

- 2' of 1/2 pvc

- 12" of 1 1/4 pvc 

- 3/4" of 1 1/2 sink drain extension pipe 

- #6 1/4" nylon spacers 

- 3' of 1/4"x  1/2" aluminum bar 

- 12x6 1/4" polycarb sheet 

- Any 1/2" thick plastic (i used hdpe )

-  3/8 #6-32 set screws x 4 

- 3/4 #6-32 pan head screws x3

- 1/2" #6-32 pan head screws x 17

- 3/8 #6-32 pan head screws x 8

- #6 washers x7

- 2" #10-32  bolt with matching lock nut

- 6" of 2" Dia. plastic rod ( nylon,delrin or pvc can be used) 

- 1/4" aluminum rod 

- tuck tape

- 6x6 3/4" thick peace of hard wood 

- U cup seal 9691k57

- 1.5" rubber washer 

- 1/2" of 17/32" brass 

- 18" of 9/16" brass 

- 5 3/8"  19/32" brass

- 5 1/8" of 1/2" brass

- 6x12 sheet 1/16" plastic ( I used styrene) 

Tools

- #6-32 and #10-32 tap

- drill press

- scrollsaw

- bandsaw

- holesaw

- 7/64" dril bit 

- lathe

- tools for lathe I ground my own out of H.H.S blanks because its cheaper but you can buy them if you want  (boring tool, standard bit,grooving bit)

- vernier calipers 

- screw driver 

- marker 

Adhesives

- pvc primer 

- solvent weld

- epoxy 

- epoxy putty

- hot glue

- super glue 

- goop

- lepage 100% glue or Go2glue

Step 1: The Magewell 

- Here are drawings of the mag well,trigger and support  bar for the mag well. You will need to make 2 of the side plates. These are not templates but you could probably get away with cutting them out. Just measure the drawing when you print it and see if its close to the dimensions.   These parts are made of 1/4" polycarb

It will look like this when its done 

 make the aluminium  bar before you put the mag well together.  it will help you line everything up correctly. 

Step 2 : Body 

- Cut 20 1/4" of 1 1/2" thinwall pvc. divide the pvc into 8 sections. I like to use one colour for the 1/4s and another for the 1/8ths. mark out the mag well slot by  starting at 7/8" from one side of the pvc and ending at 4 5/8", make it 1" wide and cut with a dremel this will now be the front of the blaster. 

Step 3 : Slots 

- place the body with the mag well facing towards you and mark out the slots. They start at 5 3/4" and end at 10 1/4", make them wide enough so a #10-32 bolt slides freely. Sorry for the bad picture. 

Step 4 : The breach support  

This is the part you need a lathe for. Get your 2" rod and cut it 1/2 longer then you need it to be, that will give you lots of room to face off the part on both sides and make both faces square. When you are making these parts make sure to have a scrap peace of the 1 1/2" thinwall pvc with you to check the fit of your parts.adjust  the size of these two parts to what ever you need, they should be able to fit into your pvc easily but not be able to slide too much. Wile your at the lathe go ahead and make the aluminum support  bar for the mag well too.  Im sure there are other ways to do this though. I drew a quick sketch of the parts 

They will look like this when you are done 

Step 5 : The catch 

Make a standard rainbow catch. Templates can be found here: http://nerfhaven.com/forums/topic/20330-rainbow/

now cut a  5" peace of 1 1/4" pvc and screw the rainbow catch in place using set screws. it should look like this when you are done 

Rap e tap around the tube until it fits in the 1 1/2" thinwall pvc 

Now line up the catch tube so its flush with the back of the 1 1/2" pvc body and mark where the catch hole need to be. Now drill a hole where your mark lines up with the the next 1/4 line over from the line you make one of the slots on. This will now be the bottom of the blaster.

The hole will need to be big enough to let the catch screw slide freely but small enough so the spring has something to rest on. If you mess up and make it too big its not a problem the spring will rest on the 1 1/4" pvc that is nested inside the blaster.  After you have done this put the catch tube in the blaster and screw in the catch screw, this will hold the tube in place for now.

put  3 or 4 screw though the 1 1/2" and 1 1/4" pvc to hold the catch tube in place, make sure to not hit the catch with these screws. The placement of the screws  does not matter but make it look nice 

step 6 : The plunger tube 

Get your 1 1/4" thin wall pvc and cut it to 6". Now get your 1 1/2" sink drain extension pipe and cut a 1/2 peace. Take your 1" to 1/2" pvc bushing and tap with tape until its snug in the drain pipe. Solvent weld the peaces together so the front of the bushing is flush with the 1 1/2" drain pipe. Now get a stub of 1/2 pvc and solvent weld it into the bushing.  Next measure 3/4" from the front of the part and cut( make sure its dry first). It should look like this when you are done 

Now that you have your 3/4" long plunger cap  solvent weld it into the 1 1/4 thin wall plunger tube so it is flush with the front. After it is cured drill a 5//32" hole 3/8"from the front of the plunger tube, make sure its going straight through.  It should look like this when you are done. 

Step 7 : The breach 

The sized of brass used will depend on if you make a 17/32" barrel or a 9/16" barrel. I used 9/16". First measure out 17" of  your barrel material ( i used 9/16"). next measure 4 1/4" from one end of the brass and mark with a sharpie. Now draw a line around half of the brass then draw two straight lines to the end of the brass. Shade in the area and cut it out, i Used a band saw with a metal blade but a dremel  works just as well.  It will look like this when you are done 

I lost the pictures for this part but its very easy. Cut 10 1/2" of 1/2" pvc and 1" pvc then glue the 1/2" pvc into the 1" pvc so 2 1/2" of the 1/2" pvc is sticking out of one end of the 1" pvc. You may need to sand don the 1/2" pvc. Once it has cured take your brass barrel and glue it into the 1/2" pvc so that the end of the barrel is flush with the 1/2" pvc sticking out of the 1" pvc. Make sure to add tightening rings to the brass (if you want to ) before you glue it in. It should look like this when you are done. 

Next we are going to make the bolt and pusher, if you are using a 9/16 barrel like me you will need 19/32" brass and 1/2 brass.  Cut 5 3/8" of your 19/32" brass and 5 1/8" of your 1/2 brass. now cut 1/2" of your 17/32" brass and  9/16" brass. Now super glue the 17/32" brass into the 9/16" brass then super glue that onto one end of the 1/2" brass this is now your pusher . after you have done this carefull drill a 2 7/64" holes anywhere in the 1/2 pusher, make sure to debur the holes. These holes will prevents a vacuum forming  behind the dart then it is being loaded. Next take your 19/32 brass and super glue it onto the pusher. Your bolt is now done. I used a peace of 5/8" brass to bridge the gap between the 19/32" and the 1/2 pvc but you can use e-tap if you dont have any. It will look something like this

Now that you have this peace you can glue it into the plunger tube. Make sure none of it sticks out on the inside of the plunger tube. I used Lepage 100% glue for this because its strong but flexible, if your in the states this is called go2glue. Once it is cured you can carefully drill though the brass using the holes that you already drilled in the pvc plunger tube. To make sure everything is air tight put a ring of glue (goop or Lepage 100% glue/go2glue) around the bottom of the brass and let it cure, next put a layer of glue all over the front of the plunger tube. I dont have a pic of this sorry. 

Step 8: The pump grip 

Take your aluminum bar and cut two 14 1/4" peaces. Make sure one end is nice and square and round off one end.  Now cut a 3 1/3" peace of 1 1/4" pvc and 1 1/2" pvc and nest them together, you will need to rap the smaller size with e-tape. Now  on the rounded side of the bars drill a 3/16" hole though both bars, to make sure the hole is in the same spot on both bars i like to tape them together with some packing tape.  next drill 3 --- holes on the square side of the bars, i drilled them 1/4" apart.  Now that you have done that put everything aside, the holes that will allow the bars to be attached to the pvc are drilled later.  This would be a good time to make a grip for your pump if you want to. Mine looked like this when i was done 

Step 9: the plunger 

Get your 1/2" nylon rod and cut it to 10 1/2" next make your catch notch 5 1/4" back from one end of the rod (it must be omni directional). This one was cut on a lathe.  If you do use a lathe, center drill one end and then drill a 17/64" hole about 3/4" deep then tap with a 6-32 tap.

Now get your 1/4 polycarb( 1/4" hdpe works too) and cut 3 disks, two disks using a 1 3/8" hole saw and the other with a 1 1/8" hole saw. Once you have that done get your u cup and put the small disk in the center of it then the two other ones sandwiching it the screw it onto your plunger rod.I have a 1 1/2" rubber washer under my u-cup but its not necessary.   I padded mine with some craft foam and a rubber washer.

I made a spacer for more spring compression out of 1/2" pvc and cpvc and come 3/4" pvc but its not necessary. It helps performance quite a bit in my opinion though. 

Step 10: handel 

Cut 2 1/4" of 1 1/4" pvc, chamfer both ends then cut the top off. This cut does not need to be perfect it will be cleaned up later. Do not take a lot off though, just enough to give you room to screw in the handle. You can make the handle any shape you want, I made a simple one out of oak. Attach the handle using 3 drywall or wood screws, i like to us 1/2 screws on the outside holes and a 1" screw in the middle. I also put some epoxy around the joint between the wood and pvd to smooth it out but its not necessary. Stain or paint the handle how ever you want, I just rapped e tape around mine. It will look something like this when you are done 

Step 11: The stock 

Cut a peace of 1 1/2" pvc how ever long you want then cut a peace of 1 1/4" pvc the same size. Glue the 1 1/4" into the 1 1/2 then glue that into the elbow. It will look like this when its done 

Step 12: trigger housing

 Cut three disks that will fit snugly in 1" pvc  from you 1/2" plastic , I used a small peace of 1" pvc to trace the inside of the pipe onto the plastic.  Next cut a 14" peace of 1" pvc. Cut the top off of the 1' pvc your taking about a little bit more then 1/4 of the pipe off. The goal of this is to have it sit nicely onto the 1 1/2" pvc body. Now put your disks indie the 1" and mark how much need to be taken off of them for everything to sit nicely onto the 1 1/2 pvc. After you have done that cut a slot on the bottom of the pvc, it will start 1" from the end and finish 2 1/2" from the end,this will allow the trigger to slide.  Now take the disks out of the 1" pvc and cut groves in the bottom of them big enough to let the trigger slide though them. Next cut a small triangle out of polycarbonate, this may take few tries to get right, I dont have measurements for you sorry. Secure the triangle into one of the disks using a small pin, the triangle  must be able to move, it will be what pushes on the catch screw. Here a some pictures of mine, if this does not make sense watch the video that is linked at the end of the wright up. 

Step 13: assembly 

Get your front magwell and insert it into the blaster, next get your front breach support peace and insert it into the front of the blaster, it should be pretty much flush with the pvc. Secure the front breach support with 3/8" 6/32 screws, i used 4. Next get your back breach support and slide it in the back of the blaster until it fits into the other side of the magwell. Next you slide your plunger tube with the plunger and springs in it into the back of the blaster, make sure you lube the plunger up well.  Next screw in your catch tube into the back of the blaster, you want your plunger rod to be sicking out of the catch by at least a 1/4" but no more then 1". Your should have something that looks like this now. 

here is a pic of how the internals are in the blaster 

Now screw on the trigger housing and stock. The trigger housing is supported by the magwell and the straps. Screw on the stock using one long screw at the bottom of the stock, you want the screw you go though the trigger housing, this will make sure it does not move backwards.  

The last thing to do it to put the pump on, get your 2" 10-32 bolt and screw on the aluminum bars with it and secure with a lock nut on the other side, you do not want to over tighten this. Next slide the pump onto the front of the blaster and screw it to the aluminum bars. You can play around with the location a bit but make sure you can prime the blaster. 

NOW YOUR FINALLY DONE!! GO SHOOT SOME FOAM! 

A link to a video with a fireing test, range test, trigger demo and some ideas on how to now use a lathe will be up shortly. Thank you for reading, hope this helps. Questions are welcome 

Link: https://www.youtube.com/watch?v=35TzVKIyOp0

Does anyone have templates, measurements, etc. for a Quadshot catch? I thrifted one and the catch is broken, so I need to machine a new one. 

Why hello there boy and girls of the internet and nerf fans all around. Im sure you know that most writeups here on the 'haven use the imperial system and not metric. So how are other people from other countries supposed to make NIC blasters? Well they cant really unless they get special orders or get it from a US distributer! But this is where a new finding comes in! 3d printing filament made of petg. It is super strong and flexible and can survive the pressure from a fully grown male with just a bit of flex.

These rolls are cheap only being at around 20$ a roll. And it doesn't matter how high your 3d printer can print because you can buy a cheap 5$ soldering iron to melt it together. Its best temperature is at 245 celsius. It comes in all different colors. Here is the clear petg on amazon all you do is look up esun petg. http://www.amazon.com/gp/aw/d/B00PQD7GRQ

How do I make templates for working with sheets of polycarb? Should I use Inventor? AutoCAD? Something else?

A while back I posted this in the homemades pictures thread.  In short, it was a blaster whose energy source was a constant force spring, like the kind used in Raider drums or your tape measure.  Specifically it was 9293K12.  For those who are not familiar, a constant force spring is a flat piece of metal wound in a coil around some sort of central shaft or bearing.  When you pull on the free end, the coil rotates around this shaft and unwinds.  Because pulling the free end farther only unwinds more of the spring, it doesn’t get any harder to pull as you pull it farther, hence the ‘constant force’ descriptor.

The origin of this experiment is several years ago when a poster on this forum (I can’t remember who it was or what the original context was) offhandedly mentioned constant force springs.  Fast forward several years and I have a job, disposable income, and boredom, and decide to give this a shot.  The original plan was to build a new blaster to run the experiment with, but I got lazy and retrofitted my extension spring rainbowpup instead.  Because of the nature of constant force springs they can really only be put into rainbowpup/eslt/whatever type blasters with plungers that are pulled instead of pushed. 

I’m going to drop some physics on you guys here.  I wasn’t sure exactly what spring to get, or how strong it should be.  Constant force springs really are a completely new area, so there are no “standard” springs or rules of thumb or anything.  Constant force springs don’t have a “spring constant” like compression or extension springs do.  So how to compare?  I didn’t come up with a good answer to this until much later.  What I eventually did was just guess and pick a spring whose draw force was about halfway (a little more actually) between the no-extension and full-extension force of the 9432k125 I found for my rainbowpup.  After buying the spring I realized that the best comparison was probably energy release.  The potential energy stored in a compression or extension spring is given by the equation E=0.5Kx^2 where E is the potential energy stored by the spring, K is the spring constant, and x is the displacement of the spring.  The potential energy stored in the K125 spring at the 6.5” of draw I use is therefore 65.4875lbf*in or 7.4J.  The potential energy at rest (I use no pre-extension) is 0J.  So the total energy released during firing (not all of which goes into the dart) is 7.4J-0J=7.4J.  So for the most equal comparison I should find a spring that can release 7.4J over 6.5in of travel.  Turns out by complete accident, I hit that on the nose with the spring I bought.

The potential energy of a constant force spring I couldn’t find online or in my machine design textbook, so I derived it.  (If someone finds a mistake in this result, please let me know, that might explain some things).  What I got was E=Fx where E is the energy released, F is the spring force, and x is the displacement.  So our total energy here is 68.9lbf*in or 7.78J. 

Note that the displacement term in the compression/extension spring is quadratic, while the displacement term for constant force springs is linear.  That means that for higher draws, the constant force spring falls behind in energy very quickly, but for this blaster/spring combo, I had almost exactly the same energy, so I moved forward with this.

So theory over, let’s talk practical application.  The edge of the spring needs to line up with the plunger rod, because that’s where the free end comes off.  To accomplish this, I used a 1.5” pvc tee and carved it to the nines so I could mount the spring a little off to the side.  I drilled a hole through the tee and used sliding door bearings to hold the spring.  I ground them down so one edge of each could fit into the ID of the spring. 

For attaching the spring to the plunger rod, I used a section of ½” nylon rod (the same material used for the plunger rod).  One end was threaded to screw onto the end of a small stud with the priming disk on it.  The other end had a slot in it, into which I inserted the spring.  A small screw goes through a hole in the end of the spring (the spring comes like that) to affix the two together. 

Assembly is a bitch.  To get the spring into the tee, I had to hold it in place and slowly thread the bolt down through the tee, alternating between rotating the bolt a turn or two and then going back and rotating these nuts a turn or two.  Once that was done, I inserted the plunger extension into the front of the blaster body.

That is where it sits at rest, so I had to stick my finger in the tee at the front and force it down towards the plunger rod. 

Then I turned the plunger with my other hand to thread the two together. Not fun.

So how does it shoot?  Not well.  I’m not sure of the exact reason now, but this blaster had trouble.  About one in five darts didn’t leave the barrel.  The ones that did didn’t seem to shoot as hard.  I don’t have a chronograph, but range tests show a clear drop off. I have a couple theories for why this could be.  First, while this spring is labelled as ‘constant force’, it isn’t like that, not quite.  Constant force springs take a small amount of travel before they reach their listed force.  I guess this is due to the shape of them or something.  I have a couple inches of pre-travel built into this setup, but maybe it isn’t enough.  Further, there is almost certainly more friction in this setup compared to an extension spring.  The bearings I used are a source of some of this, and the priming disk in the middle of the plunger rod is surely rubbing against the inside of the body because of the shape of the spring pushing it sideways.  There is also a possibility that the spring, which is 1in wide, is scraping on the inside of the front body of the blaster.  One final reason is that the process of disassembling this blaster and replacing the spring seems to have messed up the rod seal a little bit.  I’m not sure why, and it doesn't seem bad enough to account for all the problems I see.

I said in the pictures thread that “this is the weirdest thing ever”. What did I mean by that?  Well, it primes like nothing else I’ve ever used.  I’m not even sure how to describe it.  “Light” is almost right, but that isn’t really it.  I end up smashing the priming handle hard against its stops almost every time I prime it.  It’s like I begin to prime back and am expecting a certain amount of force based on how much resistance at has at the beginning, but then it throws me for a loop because that extra resistance doesn’t come.  I’m sure I could get used to it eventually, but it is pretty weird at first.

So, difficult to assemble, expensive ($10.83 for one spring!), weird to prime, and not shooting quite like you’d expect.  Are there any upsides?  I don’t know.  If you could find the right spring, and get the geometry correct (no grinding), you could make one of these that shot pretty well and maybe felt like it had a weaker prime, but I don’t consider that worth it.  Extension springs already have pretty light primes for how well they shoot, and I don’t see this offering enough advantages to overcome the disadvantages.  I’ll leave the blaster as-is for a little while if anyone wants more pictures or wants me to do any more tests, but I don’t see a good reason to keep it as it is forever.

I thought I would share some code I have cobbled together for controlling my brushless Stryfe with an arduino controller.  This allows for push button spin-up and you don't need to use a servo tester to control the motors which is always good.  Any suggestions are always welcome.   There is code included that allows you to hook a servo up to feed ammo into the flywheels for those of you who want to replace the pusher motors in your rapidstrikes with a servo.

Feel free to modify this like crazy and do all sorts of strange things with it.  This can be easily incorporated into ammo counters as well to have a single controller do both (any Arduino board is more than powerful enough to not blink at the task).

Latest version of code can always be found here: https://github.com/udsaxman/ardunerf/blob/master/ArduNerf.ino

Code as of now:

//Arduino program to control a nerf blaster with brushless flywheels and a servo for feeding darts into the flywheels
//The pushbuttons I'm using in this example are OSEPP Push Button Modules  http://osepp.com/products/sensors-arduino-compatible/push-button-module/
//Arduino controller used during this development is an Intel Curie powered Arduino 101 https://www.arduino.cc/en/Main/ArduinoBoard101with an OSEPP SensorShield on top of it http://osepp.com/products/shield-arduino-compatible/sensor-shield/.  You will need to use OPTO ESCs and a seperate power feed for this setup!
//Also tested wih an ATMEGA2560 based Multiwii Flight Controller i had laying around http://www.readytoflyquads.com/multiwii-pro-2-0-flight-controller. To use this you will need to make sure one of your ESCs has a BEC built in.
//ESCs utilized here are http://www.hobbyking.com/hobbyking/store/__39708__Afro_ESC_30Amp_Multi_rotor_Motor_Speed_Controller_SimonK_Firmware_.html.  


#include <Servo.h> //nice and simple, we are only utilizing one library for this project.  Servo handles everything we need it to

//declare servo objects that will be used throughout the rest of the project.
Servo ESC1;
Servo ESC2;
Servo feedServo;
//arm esc
// constants won't change. They're used here to
// set pin numbers:
const int spinButtonPin = 8;  // the number of the pin where the spin button is connected
const int feedButtonPin = 7;  // the number of the pin where the feed button is connected
const int ledPin = 13;      // the number of the LED pin
const int ESC1Pin = 5;      //piuninumber of the first ESC
const int ESC2Pin = 6;     //pin number of the second ESC
const int feedServoPin=9;  //pin number for the servo that will be pushing darts into the flywheels


// Variables will change:
int ledState = LOW;         // the current state of the output pin
int spinButtonState;             // used for storing the current reading from the spin input pin
int feedButtonState;             // used for storing the current reading from the feed input pin
int lastSpinButtonState = HIGH;   // the previous reading from the spin input pin - we instantiate it to the non-firing position to start the program
int lastFeedButtonState = HIGH;   // the previous reading from the feed input pin - we instantiate it to the non-firing position to start the program

//if not all your ESCs are the same, you may need an additonal variable but that shouldnt be necessary here.
int ESCMinSpeed = 1000;   //this varies by ESC.  Min speed must be low enough to arm.  Refer to speec controller's documentation for this
int ESCMaxSpeed = 1800;   //this varries by ESC.  You may want to set it slightly lower than the max supported to avoid overheating issues


void setup() {
  //setup the pins so we can use them for reading the button state.
  pinMode(spinButtonPin, INPUT);
  pinMode(feedButtonPin, INPUT);
  //set ledPin to output power to the LED
  pinMode(ledPin, OUTPUT);
  //set initial LED state
  digitalWrite(ledPin, ledState);
  //attach servos
  ESC1.attach(ESC1Pin);  
  ESC2.attach(ESC2Pin);
  feedServo.attach(feedServoPin);
  //write minimum speed to ESCs so they arm
  ESC1.writeMicroseconds(ESCMinSpeed);
  ESC2.writeMicroseconds(ESCMinSpeed);
  //wait 1 second for ESCs to arm
  delay(1000);
}

void loop() {
 
  // read the state of the switchs into a local variable:
  int spinReading = digitalRead(spinButtonPin);
  int feedReading = digitalRead(feedButtonPin);
 
      // check to see if you just pressed the button
      //only change speed if button state has changed
      if (spinReading != lastSpinButtonState) {
        if (spinReading == LOW) {
           ledState = HIGH;
           ESC1.writeMicroseconds(ESCMaxSpeed);
           ESC2.writeMicroseconds(ESCMaxSpeed);
        }
       if (spinReading == HIGH) {
          ledState = LOW;
          ESC1.writeMicroseconds(ESCMinSpeed);
          ESC2.writeMicroseconds(ESCMinSpeed);
        }
      }

      //if feed button has been pressed, start pushing darts out
      //What you write to the servos will vary greatly depending how you setup the feed mechanism.  
      //This example has the servo pushing a dart in when you push the button and then moving back to get ready to push the next one when yo let up on it.
      //In a rapidstrike or similar, you can just set ti to keep spinning while the button is pressed
      
      if (feedReading != lastFeedButtonState) {
        //if button is pressed, feed a dart in
        if (feedReading == LOW) {
          feedServo.write(180); //writes the server to full rotation
          }
        //return servo to the withdrawn state when button is released  
        if (feedReading == HIGH) {
          feedServo.write(0);
        }
      }
   
 
    // save the reading.  Next time through the loop,
    // it'll be the lastButtonState:
    lastSpinButtonState = spinReading;
    lastFeedButtonState = feedReading;
 
  // set the LED:
  digitalWrite(ledPin, ledState);

}

I attempted to attach the .ino file but the forums don't seem to be a big fan

FOREWARD

This guide is in response to the several emails per month I receive about 3D printing, and it is easier to throw everything out there once than having to regurgitate the same information a dozen times to as many different souls. People unfamiliar with the art seem to forget that it’s not magic, and it’s not the end all answer to your homemade nerfy engineering problems, so whether you are on the fence about getting your first printer, have some ideas about a new groundbreaking 3D printed blaster, or have your own printer and need some advice in parts design or printer settings, here is a condensed summary of all my experiences to get you started. Please keep in mind the information presented here is nothing new, you can google most of this yourself and find similar results, I've never been able to find a single source with all the information I present here; I am no expert, but I do print a lot and have found a nice set of guidelines I like to follow. So think of this more like a noob’s guide to 3D printing. Chime in with your experiences too, everyone’s mileage is a little different.

1. BEFORE YOU BUY

1.1 Things to Consider

Think about your hobbies outside of nerf, how often you will realistically use your new toy, and what other applications you will (read WILL, not COULD) use the printer on. The printed products are often unsightly in their monotone colors; they will not impress your non-techy significant-other and are not really suited for furniture grade applications, however, I have printed cupboard hinges, light fixtures, and small statues with mine, and myriad other non-stress-critical applications are good places to use a printer in your everyday life.

1.2 Types of Printers and their Specifications

These consumer requirements that you have identified will lay the foundations for the specifications of your printer, most notably, the size. There are two figures to keep in mind here. Firstly, the printer dimensions. Self-explanatory, the physical space the printer will occupy on your desk, table, workbench, etc. The second is the print volume. This one is a little bit trickier and will vary based on the type of printer. “Delta” configured Printers will have a print volume that is shaped like a cylinder, and the print bed will be shaped like a circle. Most other types of traditional 3D printers, sometimes called “gantry” or “X-Y” printers will have a print volume that is box-shaped, with a rectangular shaped print bed.

1.3 Types of Printer Filament, the “Ink” to your printer

The two main types of print materials are ABS and PLA, sold as rolls of filament. Basically the “ink” to your printer, and each type has its’ own benefits and drawbacks. I print exclusively in ABS, mainly because of the relatively low melting point of PLA, and I am wary of the spooky materials sciences surrounding plastics as they approach glass transition temperatures. PLA transition temps is 70-80 °C, where ABS is 220-240°C. Read: you are probably fine with PLA, but I just prefer to be on the safe side of things, coming from a region of hot, humid summers. So this guide will focus mostly on printing with ABS.

This being said, ABS is a pain to keep under control. It likes to be kept very hot and requires the use of a heated bed and adhesive to keep it stuck down while printing, seen below. Most materials, thermoplastics in particular, like to shrink when they cool down. Essentially, as the top layer of ABS cools on top of a layer that is already hardened, the top cooling layer acts like a flexing muscle, and as it shrinks, pulls up the layer underneath it. This phenomena leads to “curling” of the ABS, causing the edges of a printed part to peel off of your hot bed, and may cause delamination between layers, i.e. the separation of the layers mid-print. No bueno for stresses. We’ll get into the engineering a little later. Additionally, ABS carries more odor with it than PLA. Not necessary a bad odor, but one that you’ll have to get used to should you print in an office or something. Below, you can see the ABS on my part curling up from the bed. The glue was 2 weeks old and I forgot to wash and reapply the glue properly. Luckily, this is only a prototype part and it's not going to be going on any blasters long-term.

For PLA, a hot bed is not absolutely necessary (but still recommended), and because of its’ low melting temperature, is less likely to curl up on you, and produces less odor than ABS, but I’ve heard it is more likely to jam up in your printer, so maybe a little bit more of a maintenance hog. It is also more environmentally friendly than ABS, as it is made from plant based oils. I have far less experience with PLA, so someone else that uses it is free to chime in.

1.4 The Shit Nobody Talks About

There are so many drawbacks and inconveniences to 3D printers, and I will mention a few here and go into depth several of them in this novella. For one, TIME! I am printing a receiver for Nerf magazines for a PCSR variant, I’m only making it as a prototype, yet this 4 x 4 x 3 part is going to take 12 hours to print and it’s only a prototype part 4 layers thick! Damn, there is almost always a better way to do things than 3D printing unless your geometry is incredibly complex.

SMELL! ABS smells up your room. SOUND! I need headphones/earplugs to be able to sleep at night any more if I make any overnight prints. TEMPERATURE! If your print room is cooler than like 80 degrees, your prints will tend to delaminate and peel off the bed. TROUBLESHOOTING! DIY printers means DIY fixing. If parts break, you have to take the initiative and reverse engineer some of the parts/ go back into the manual and figure out what’s wrong. This experience was a crash course in electronics, mechanics, and stress application. Luckily the Rostock has a great instruction manual. LIGHT! If printing at night, the display is backlit and I have yet to modify my code to turn it off. SAFETY! We’ll get to that in a minute.

1.5 Pricing

All of these factors, maximum temperatures of the hot-end, type of printer, size of printer, the inclusion of a heated bed, will all affect the cost of your printer. I have seen some for as cheap as $200. Some are as expensive as $3000 for consumer models. Some are pre-built, other have some assembly required or come as kits, and hell, if you are good enough you can literally build your own from zero (Read: You probably aren’t good enough to build your own from zero.) I chose the Rostock Max V2, a kit-build, with everything included in the box, just nothing put together. The wiring, mechanical assembly, soldering, tuning, and troubleshooting, and troubleshooting, and troubleshooting was all left to me. If you want a fun project, and are confident in your building/tinkering skills, I say go for it. If you just want to get printing already and can’t be bothered with the VERY likely screw-ups of DIY, then a pre-built one might be the way to go. Market price for my printer is $1,000 for the kit, but because I put it together myself, I have the print volume of a printer twice as expensive.

Being builders of homemade blasters, most of us reading this are probably very mechanically minded individuals. If electronics and software aren’t your thing, I’d say don’t worry too much. If you have a kit build, read through the instructions and jot down any questions you have, find community resources, reach out to the company, google how to make proper connections, etc. I had no problems with my Rostock instructions, they were very thorough. As for software, it is my understanding that most kit builds operate on software that can be downloaded from a community site. For my printer, I didn’t write a single line of code! It was downloaded from an open source webpage for 3D printers.  This will probably be the case with almost any other kit or pre-built printer you come across.

One last thing to consider is the community of people surrounding your printer. Is the company reliable and trustworthy? What do the reviews say about this printer? Are experiences generally positive? What do these guys use theirs for? Feel out the market for something you like.

It’s all very specific to each person and is a decision that is ultimately your own to make. This is where I cannot help you. Research the shit out of printers and find one that you like. Hell, go on craigslist and see if you can get a used one for cheap. Fixing a broken printer or building it from a kit really gives you an idea of the things’ personality. It’s hard to explain. But it feels right.

2. THE GOOD STUFF

2.1 Terminology

I guess now would be a good time to introduce some of the common vernacular we use round these parts, if things weren't technical enough for you yet.

Below is a half-finished part that I hang on my wall to demonstrate some of the physical phenomena of 3D printing. I have referred to "layers thick" a few times already, and this is precisely what I am referring to, more correctly called "perimeters". Generally, the more perimeters you have around the outside of your part, the sturdier it will be. You can actually count the number of perimeters I have here, This one is 6 layers/perimeters thick. When I say "layers thick" this is what I mean, as opposed to "layers tall" or how many individual, horizontal layers make up your part (the number of cards stacked up in your deck).

The second quality to note is all the cross hatching hexitriangular nonsense you see in between the perimeters. This is called "infill" and basically allows for the print to be completed faster than if it was a completely solid part, and still keep the finished product relatively strong and lightweight. The infill basically forms many little "tubes" that follow the layers vertically upward, the view you see below is a "top" view, so the print bed was originally on the underside of this part. Not much to say here, except I like to keep my infill about 40%. This means 40% of the inside volume is occupied by the infill filament, and the remaining 60% is air. You can go anywhere from 0 to 100% infill, but at some point diminishing returns kicks in, and I supposed if you wanted to make a totally hollow part that's how you could do it.

My Rostock is a delta style of printer, so these next parts may not look exactly like they do on other printers, but the principles and functions are identical. Below is a photo of the hot-end printing a part, now using green filament. The "hot end" is the general name for the entire assembly that heats up the solid plastic filament to a hot and sticky goo. That whole big thing. The nozzle is the tiny little brass thing at the very bottom making contact with that part that lays down the next layer. Those wires you see are hooked up to two heating resistors buried inside the hot end that heat the whole thing to 235 °C. If you've ever hooked up a resistor to a battery, you know it gets hot. Same idea here. All that orange cellophane looking stuff is actually a special heat resistant tape called Kapton. Keeps everything in place and doesn't melt until like 400 °C or something ridiculous like that. 

2.2 Design of Parts

So you have your printer and now it’s time to design your own parts. This step is optional, if you just want to spit out pre-made parts there’s nothing wrong with that, but this is my hobby and I’ll cry if I want to. Good parts design is crucial to having printable components. I use Autodesk Inventor and save parts as their solid parts, as well as .stl, this seems to be the format that 3D printers like.

Remember that 3D printing is really just like stacking a deck of cards, one by one. Each card is only a few thousandths of an inch “tall”, but several inches long and wide. One card placed on a table is almost two dimensional. Stack 52 cards on top of each other, and look at that, you have a tangible 3D rectangular prism shape! Think of each card as a “layer” of the print; it may not be a rectangular shape, but you get the analogy.

Each layer is supported by the layer underneath it, or at least that’s what we are shooting for with parts design. I’m going to give you some examples of good and bad parts right here.

Let’s say I want to make this bracket shown below, measuring 3 inches tall, 3 inches wide, and only 1 inch deep. Is this a good orientation to print it? I.e. should the face currently on the bottom be what’s touching the hot bed?

No. mostly certainly not. The Top-Left arm is not supported by anything underneath it. Remember the deck of cards analogy, now imagine each card is not rigid, but rather made of jelly. Each card is supported by the layer beneath it. With nothing to hold up that first layer of the bottom of the arm, the hot filament will fall right to the ground as it exits the hot-end. It doesn’t cure instantly, in fact the filament takes several seconds to fully cure/harden/cool. Like squirting elmers’ glue out of the bottle, it becomes a solid eventually, but it takes some time to get there first. Our “glue” dries faster, but it is still essentially a liquid when it’s squirted out, all the same. My rule is that every “arm” like this must have a lower face that is at least 25° away from horizontal. I think Kane’s rule is 45°, like I mentioned, everyone’s is different.

So we have two options here: Fix the part by applying the rule I mentioned above, or change the orientation of the part so another face is touching the hot bed. I will opt for the second one this time around…. So is this part “printable”?

Hmmmm, I’d say it’s better but still not ideal. The channel on the bottom left part is left unsupported again, and will probably sag or produce a sloppy couple of layers. The circular holes shown typically aren’t as problematic because even though they are technically unsupported from directly below, they sort of build up to that point of being unsupported, and much like an arch bridge, provide enough support while it’s being printed to be not of major concern until the diameter exceeds maybe 2 or 3 inches.

So what do we do here? There are two options: Either change the orientation again or allow the use of support material on you printer software. I don’t like support material mainly because it seems to promote the use of poorly designed parts rather than making parts that are honestly better and stronger to begin with. Plus, it adds more steps to the end process of finishing off the parts, and leaves jagged or pointy bits that are uncomfortable and unsightly.

On this next orientation change, again we are left with some options. Either rotate the part again, so the channel is vertical, (which would work because it’s now essentially a circular hole on the top that will be supported well enough as previously mentioned,) or turn it on its’ side. This second option is probably the better one. Why? Well if each layer is only 0.2mm thick, the general rule is that it will always take longer to print vertically than horizontally. So if you can keep your parts short, keep your parts short. Let’s turn it on its’ side….

This is probably the best way to print this part, with one last little change I want to make. The first layer of your print is the most important, as a good bottom “bed” layer will ensure the best adhesion to the bed for the duration of the print. Small little details are not usually good for this, as they are likely to get knocked off during that crucial first layer of print. What I usually do for complex pieces is make a “raft” for the part that covers all the holes and smooths out the bottom face of the part. Below, all I’ve done is drawn a square bottom to the part and extruded it 0.030 inches, or about 4 layers. This is easy enough to remove with a knife or drill bit for the holes, and makes sure there is good contact with the hot bed. It adds some time to the print, but it helps with adhesion and therefore final quality in my experience. In short, the first layer of your print should always be kept SIMPLE. No holes, no weird wavy or jagged geometries. Keep it simple. A square, a circle, a rectangle.

Another thing to keep in mind is the size of the part, or thicknesses of peninsulas on each layer. For example, the part shown below has a crack about midway up the far wall, because it is only about 1/4 inch thick at that point. Thin walls have the same tendency to curl up, but don't have the interlayer surface area to hold the top layer down like thicker layers. Something to keep in mind while designing, and just another reason 3D parts often look blocky or bulky. Also, a crack is visible on the close wall, right at the transition from angled to vertical where the magazine will eventually sit. This is due to a sharp angle transition, even one that small leads to a big stress concentration. This is why it's a good idea to make "prototype parts" first, that will print faster than the final part, and will reveal weaknesses in the design that may not have been apparent initially.

2.3 Principles of Engineering

Good parts design is essential to parts that aren’t going to fail in the field. I can tell you firsthand that just making the part a few layers thicker isn’t always going to solve your problems. The first generation of pullbacks were embarrassingly not up to the task of full on outdoor nerf wars. That being said, these failures have taught me a good deal about the weaknesses of 3D printing, and the amount of working around you will actually need to do to make a sturdy and robust part.

The first thing to remember is that these are literally individual layers that are sort-of-not-really adhered together. The filament extruding from the hot end never gets to a truly molten state, and rather just reaches a sort of glass transition temperature. The filament while being extruded gets squishy and sticky, but the layer beneath it is still fairly cool. A chemical bond is never actually formed between the layers, and the rule of thumb is that the 3D printed strength of an item is 30 percent that of an extruded/ injection molded part. Yeah. Less than a third of the strength. This is where people seem to have issue. 3D printing is not the golden goose egg to homemade blasters. Like a drill press, or a scroll saw, or a belt sander, it’s just another tool, and you don’t NEED any of them to make a banging Christina Hendricks (or Chris Hemworth, depending on your mood) homemade. Don’t forget that. You can’t just print anything you want willy-nilly. Go ahead, try to print a sentinel shell or something. It will literally fall apart. This is why the printed blaster parts we are familiar with are often thick or goofy looking. They NEED to be that way to even be a fraction the strength of their counterparts.

Morever, think of the stresses on the part. The interlayer surface planes will always be the weakest link in the part. Pulling apart the layers is pretty easy for example (tensile stress), but the parts handle COMPRESSION stresses very well. I’ve actually printed a set of longboard risers which are holding up with no problems because they are sandwiched between the metal trucks and the wooden deck, and are always in a state of compression. The PCSR catch shown below holds up well because the interlayer forces are largely compressive with a bit of shear. Reason out the stresses. Draw a free body diagram if you need to to visualize the forces. FEEL the stresses in your parts. An extra five minutes on paper will save you like seven hours on the print.

Think about the bearing stresses too. The force that occurs when a screw or bolt or rod is put through a hole in your part. It’s going to want to split your layers apart, whether pushing apart the layers like an axe, or prying them apart like a crow bar. Distribute these stresses wisely. Think 4 screws are good enough? Use 6 or 8. Be generous with your factor of safety. If your stresses are directly in line with tensile forces, there is a good chance that your part will be overstressed. If you have high stress components, either print the layers at an angle to the forces (to mix shear and tensile stresses) and ensure all your sharp corners are rounded out. Filet everything you can get away with. Sharp corners are particularly pronounced in 3D printed parts. Layers will almost always separate on a sharp transition. That first example we did REALLY should have a quarter inch filet on that inside corner….

That’s better. Additionally, below is a comparison of the original pullback handles, with the mk V and up handles, with gradual filets on the inside corners, and a completed redesigned shape, with layers printed 8 degrees offset from the normal of the applied forces. Left is old, right is new.

3. PRINTER SETTINGS AND SUGGESTIONS

3.1 Technical Stuff

To reiterate, I use a Rostock Max V2 Delta style printer. My hotbed is borosilicate glass coated with 1-2 layers of glue stick glue, applied when the bed is cold. Wash this off with glass cleaner and replace with new glue every 6-8 prints, or whenever the ABS starts to peel from the bed. This hot bed is typically set at 99℃. Anything below 90℃ seems to peel off the bed too easily during printing. My hot end is a 0.5mm nozzle set to 235℃. Anything below 225℃ seems to result in delamination, or peeling, between individual layers, something that is highly unwanted in stress bearing components.

To combat delamination, I recommend the use of an enclosure. This can be as simple as a box made of wood or plastic, or a large storage container retrofitted with a small window and door. For enclosure heating, I have used incandescent light bulbs that I scrapped from an old desk lamp, and integrated these into the enclosure. There are certainly better heating options, but incandescent bulbs are cheap and can be found almost anywhere, and provide enough heat for my purposes. The enclosure doubles not only as a means of keeping heat in, but keeping the cold out. It suppresses the noise of the printer somewhat, and blocks the cool air of a fan or air conditioner or an open window which may provide inconsistent or accelerated cooling of your print layers.

I use Matter Control as my printing program. I print a MINIMUM of 8 layers thick on all components using the aforementioned 0.5mm nozzle, with an infill of 40%. For stress bearing components such as the Pullback under stock pull-bar, I use 10-12 layers thickness, and for rainbow catches, I print at 100 layers thick, to make sure that there is total fill on each layer. Speaking of, my layer height is 0.20mm. Smaller print layer heights have the problem of curling up on overhanging geometry, such as the back end of pistol grips, but once again, everyone’s experience is different. It’s always better to print a few more layers and wait a little longer, than rush the print job and have parts break on you in the middle of a war. Printing more layers will make your parts stronger, but if your part is poorly designed, it will merely be a bandaid on the problem.

For components with screw-holes, invest in a tap wrench with appropriate tapping bit. Tap the first ⅔ of the hole and let the screw tap the rest itself. This gives you a good adhesion to your part while preventing the part from splitting. If your part begins to delaminate or split, and you cannot be bothered to print another, I’ve found it best to apply some superglue or epoxy to the damaged area.

3.2 Community Input

Meaker suggests not to run PLA and ABS through the same nozzle or printer. This makes sense. If PLA melts roughly 150 °C lower than ABS, andy ABS chunks left in a nozzle from previous prints would remain solid, and block up the printer.

Draconis recommends using ABS pipe weld to repair ABS parts. I've never tested this before but this really seems like a good idea. I just hope the results don't mimic those of acetone. Again, everybody has a different experience with this stuff, and I'm only here to point you in the right direction if I can.

3.3 Safety

You're working with really hot things. Should be obvious but don't touch the hot end or the bed. Even if you turned it off, it stays hot for a couple of minutes. Don't be an idiot.

Everything I have read suggests that 3D printing is overall safe. I understand tiny nanoparticles are produced, as well as a negligible amount of hydrogen cyanide. As it stands now, I largely ignore these issues, but you shouldn’t. A good idea is to print in a well ventilated area, in a relatively large room, windows open, that kind of thing. My eventual goal is to have several printers running in tandem in a large closet or enclosure with a proper ventilation system, ducts with fans directing air out of a window would not be something difficult to accomplish, and would be rather modular when I get my first apartment that would not take kindly to me tearing out walls. When I have a proper workshop, ventilation will be a real thing.

Fire safety is the real big deal. Google 3D printer fires and things get not-so-pretty. Again, my ideal long term setup is to have a simple Arduino controlled CO2 fire combat system within said enclosure to starve the fire. If you are not a mad scientist by the light of a full moon, there is another product for mortals to invest in that already exists on the market. I have yet to test it out, but it seems like a good idea. It’s called smoke signal; I’ve linked it at the end of this article, and I will make a review once I have it properly installed. It only shuts off printer power, and doesn’t actually put out a fire, but it does prevent the spread of an electrical fire. In conjunction with a CO2 flood from the aforementioned system, this could be a very effective tool in fire prevention.

All this being said, do not leave an active printer unattended! Always be within earshot of your printer, and if nothing else, stick a 5 dollar smoke alarm to the top of your printer! It may just save more than your new toy.

4. THE END

Have more to add? Leave a comment and I’ll add it in. If I ever receive a nooby 3D printer question I will respectfully refer you to this article to read in it's entirety. Think some advice is faulty or inconsistent with your own experiences? Write it in a comment. Think this article sucks? Roflcopter spend 6 hours of your weekend and write a better one. Anyway, thanks for the read and putting up with my dry humor.

Nerf on you beautiful technologists and engineers and tinkerers and athletes and artists. I hope this helps you in some small way.

-Aeromech

Additional Information Provided by:

Meaker

Draconis

Resources

ABS vs. PLA

http://www.protoparadigm.com/news-updates/the-difference-between-abs-and-pla-for-3d-printing/]

ABS tips

https://www.matterhackers.com/articles/how-to-succeed-when-printing-with-abs

Rostock Max 3D printer Instructions

http://download.seemecnc.com/rostockmax/Rostock-MAX-v2-Assembly-Guide-2ndEdition.pdf

3D Printer Fire Prevention Device

https://3dprint.com/18064/smoke-signal-3d-print-fire/

So my distaste for omnidirection plunger rods is not unknown to the nerf community, up til now, they seemed to catch less reliably than unidirectional catches, and were overall more fickle. The problem comes down to spring binding issues, particularly with the K26, and maybe even the K25. As the plunger rod is pulled back and the spring compresses, it does not compress perfectly in line with the plunger rod, and tends to "serpentine", getting all wavy and kinky before it reaches it's final stage of compression. During this time, the spring gets caught in the omni-directional catch part of the plunger rod (with the lower rod diameter) and produces either a VERY unpleasant "crunchy" feeling to the prime, and often results in a "false catch" where the spring actually gets caught in that catch region when you pull the plunger rod back. You think the catch has engaged, and as soon as you begin to let go, and the spring is able to exert it's energy, the plunger assembly flies forward. This leads to swearing, sore fingers, questioning your rainbow catch-making abilities, and an overall hopeless feeling knowing that this lifeless piece of plumbing pipe has defeated you. You're better than that mate. Millions of years of evolution have prepared you for this moment. It's time to take on that omnidirectional plunger and make it yo bitch.

The "Before" photo. Here is a pullback with the main tubes "ghosted" out, so the insides are visible but you can still see the outline of the body tube. Typically, the spring binds in the recess near the front of the plunger rod, where it is supposed to engage in the catch.

This is it. This is the easiest solution ever. Cut a piece of 1" PVC Pipe, about 2.5 inches. Make sure it is shorter than the spring at full compression, but not too much shorter. Get it close, but make sure it is still shorter. Take note that the front (left side of the photo) of the tube is beveled on the inside. This is important. Put a few wraps of packaging tape around this so it fits fairly snuggly inside the 1-1/4" PVC plunger tube.

Boom. Throw it in there. Rest this piece against the front of the rainbow catch, with the beveled end facing forward. Sink two screws in there to hold it in place.

This photo provides a little more insight, the anti-binding pipe goes around the spring. When the spring is compressed, it is "guided" to a more "cocentric" position within the body tube. The bevel smoothly pushes any parts of the spring that may bulge out into position, so the spring cannot bend to the point where it would interfere with the catch region of the plunger tube. After installing this into a rainbow pistol/carbine (5 inches of draw, like 1 to 1.5 inches of precompression, 10 inches of K26 spring)  all false-catches stopped completely. The prime was smoother, and all the problems I was having with the catch vanished. It caught every time, and smoothly. Follow this guide if you're using a K26 in conjunction with an omnidirectional plunger rod.

Make sure it doesn't cover up your speed holes (anti vacuum holes). Once you sink in this piece, just re-drill the speed holes in the main body tube through the anti-binding pipe you just installed. Super easy.

Intended for this contest but can/will serve as your normal writeup for other purposes. 

This blaster is meant for new guys who have been exposed, usually online, to this little realm of nerf called DIY/NIC/whatever community involves relatively powerful homemade nerf blaster, and want to get involved. They don't have the tools and resources required to build impressive +bows and rainbowpumps that are relevant and made standard through popular media sources, and are intimated and frustrated. Here are the design goals, paraphrased from the contest thread, that we will try to meet:

·       Minimize special tools (large machinery, 3-d printers, etc.) and parts (in our case, polycarb, mcmaster springs, thinwall pvc, etc.)

·       Minimize cost and build time

·       Be competitive in wars (to a degree); much better then the modded stryfe you were planning to show up with. 

·       Be safe and easy to use 

Overview of the SNAP 

Snaps are known to be cheap and easy to make. Many people can argue that SNAPS are inferior to more sophisticated homemades, and are right to an extent. SNAPS can never achieve the elegance of a +bow, or the insane durability and reliability of rainbows. In terms of performance, this really is a point that cannot be debated IMO. Theoretically, I can conclude a perfect rainbow is more "powerful" then the most perfect SNAP, but I have yet to meet anyone with either. For me, I have always used SNAPS and am able to be fairly competitive...hopefully some people can back me up on that haha. (Note: anyone who says that a homemade is more accurate then another, that's stupid, accuracy depends entirely on the quality of dart). 

The SNAP is built out of common plumbing materials found at hardware stores, plus a strong clothespin, washers, and a spring. The explanation of it's operation can be found here, as well as various other resources on this website. It's a simple concept, and will be made clearer as we progress in building our blaster. 

Some great resources of other SNAP tutorials and explanations can be 

·       Rork's Snapbow Tutorial 

·       Superlative Plunger Head

·       NoM's Video Snapbow Tutorial

Cost and Materials/Tools Guide

Note-There is a significant difference between Sch. 40 PVC and CPVC. Be wary

·       2x 1"-1/2" bushing (one for the front, one for the back)

·       1 1/4" PVC (you will need about 11" of it, but go ahead and get more anyway)

·       1/2" CPVC Tee (the thing you use to prime the thing)

·       1/2" CPVC Endcap 

·       1/2" CPVC (you'll need a good amount, get a lot)

·       2x 1/4" 1 1/4" washers (basically a 1/4" type washer with a diameter of 1 1/4")

·       1/4" 1 1/4" Neoprene washer (might have to dig around for these a bit) 

·       1/4" 1 1/2" Neoprene washer

·       1/4" 1 1/4" long bolt

·       2x 1/4" nuts

·       Industrial strength clothespin (preferably plastic. Wood ones are usable but trickier to use in my experience. If you can't find any at all, I use these)

·       "L" bracket (I prefer the 1 1/2" ones)

·       JB Weld (not the 2 part kind, the clay-like one)

·       Roofing nail

·       Some #6 3/8" screws (get a bunch, especially if planning on working on future projects) 

·       2x HOMEDEPOT Everbilt springs found here (used commonly in Nitefinders)

·       Handle from an old nerf blaster (Wood can be nicer, but thats more materials and work) 

·       Drill with 7/64 bit, 7/32 bit, a bit a bit bigger then the roofing nail, and a 3/8 or 1/2 if you got it handy 

·       Screwdriver

·       Hot glue gun with lots of glue 

·       Pliers

·       Something to cut a handle off with, e.g. hacksaw, dremel

·       Dremel (would be nice)

·       Bolt cutter/ pliers 

       Etape 

Total Cost (everything that you buy; you might only need 11" of 1 1/4" PVC, but you have to get 2 ft.): $37.56 

You now have enough materials; building a second, identical blaster will be under $10.

Build time - 30-60 min depending on experience.

Build time+Cure time - 6-7 hrs  

On to the construction

The Plunger Head 

The plunger head is a assembly of washers and e-putty that basically makes the blaster work. It makes an airtight seal, and also is the way the blaster catches. 

Drill a CENTERED 7/32 hole in the CPVC endcap

Insert you bolt though the bottom of the endcap, and assemble your washers like so. Make sure the bolts are tight. 

Take a good amount of epoxy putty and create a ramp to the bottom washer. 

Let it set for a good amount of time. 

The Trigger 

Cut the end of the clothespin off so that spring is close to the edge.

Cut your roofing nail to size. The general length can vary between 0.8"-1.2". Start off big, the cut lower if needed. Using a dremel, or sandpaper, smooth and round the top of the nail.

Using the "bit a bit bigger then the roofing nail", drill through the clothespin. Stick your nail completely though it, and fill the gap with epoxy putty. Attach your L bracket to the end of the clothespin. 

The Plunger Tube and Plunger Rod

Cut the 1 1/4" PVC to 11". 

Using the reducer bushing, wrap etape around the bottom of the bushing until the bushing fits snugly in one end of the tube. 

Hot glue the bushing into place, drill and screw the screws into the bushing. Before you insert the screws, add some hot glue into the holes before you screw the screws in. 

Assemble the plunger head, springs, the other bushing, and the CPVC tee like so. Screw the CPVC tee in place. 

Drill a hole 4" from the back of the plunger tube with the "bit a bit bigger then the roofing nail." 

Hot glue the trigger into place, and add zip-ties to secure the trigger in place if wanted. At this point, you can test to see if the blaster catches. If it feels like the ramp is barely touching the nail, your nail is too short. If your blaster is "falsely catching", your nail is too long. You can adjust your nail until it catches. After a while, you develop an intuition and will get it on the first try. There is no calculation or measuring required, I just eye it. 

Hot glue the handle onto the back of the blaster, next to the trigger. You will probably need a lot hot glue for this, but the resulting bond will be pretty strong. 

Screw the bushing on the plunger rod on the back of the plunger tube. 

Drill some vent holes above the handle, with your 1/2 or 3/8 bit.

If everything is dry, and you tested it already, good job. Go fling some foam.

Conclusion 

Making a barrel-since every barrel material is uncommon, besides CPVC, use CPVC, no matter what darts you have. In the picture and testing, I'm using a ridiculously long barrel. I would get better ranges with a shorter barrel.

Using a 4-dart RSCB, I'm hitting low 70's, and with a speedloader, I'm hitting low 80's. A hopper works, but a RSCB seems more efficient. In a war, if you are the type of player that relies on speed and dodging instead of cover, you can be reasonably (but not fully) competitive. 

Going Further

• Barrel Guide
• RSCB Discussion
• Hopper Guide
• Pumpsnap Writeup
• Snapbow Writeup

If you really want...Beginners Rainbowpump

First writeup, welcome to criticism, questions, and miscellaneous comments. Again, this writeup is geared for the contest as opposed to a random writeup.

Hey everyone,

Hope this is the right place to post, I wasn't sure if this belonged here, or as a concept thread.

Basically, I'm hoping to 3D print a nerf flywheel blaster using a PLA printer with a 20x20x20 print capacity, that has yet to be calibrated, but having little experience with flywheels or 3D printing, I'm going to need a little bit of advice.

Firstly, because I don't have any better ideas for aesthetics, I'm planning on making a blaster with a similar appearance to the FG42, so the gun is going to be side-fed.

I've seen very little information on this online, and I'm not sure if it's because the only gun that springs to mind with side feeding is the raider (which seems largely unpopular), or if it's because side feeding is a bad design.

Secondly, I've found little in the way of people reinforcing their larger 3D prints, like stocks and grips with cheaper, stronger material like wood/metal rods.

Given that I'm planning on 3D printing the case, I'm tossing up between this or trying to find some broken/discarded nerf shells to use as casing, and building upon those instead.

Thirdly, I've several DC motors salvaged from printers I'm hoping to use.

The two on the far left are 130s, I believe, but I'm not sure of their specifications, so it's unlikely that I'm going to be using them.

From (fairly unreliable) datasheets I've found online, it appears that the third and fourth motors are capable of producing 12-15k RPM, which is no where near as fast as the desired 20k+ that I've heard reported from Rhino MTBs or the Tamiya Plasma Drives, but I feel as though through a combination of larger flywheels (3D printing custom flywheel cages is an option), and a higher torque, these should suffice.

For reference, I gather that the current "high end" motor is the Rhino MTB, producing 36k RPM, with the 2" radius stock flywheels, this results in tangential velocity of roughly 628fps, achieving the glass ceiling of 120fps

Since I'm happy achieving around 100fps, I feel as though this is overkill, especially since I only have NiMh batteries to work with. I'm wondering if anyone has any experience with high-torque, low-RPM motors like the ones I have?

Alternatively, I'm toying around with the possibility of using the third and fourth motors in my image as afterburners, with the small ones as launchers. Also, I should be able to mimic the shape of worker wheels, since I'm 3D printing the cage and wheels, anyway.

Anyway, I've got a ton of things to figure out, and I really appreciate you guys letting me post here.

I found this link: http://www.sscentral.org/homemade/check_valves.html

The stem valves used in that article can be bought in bulk lots on eBay, and you end up only paying $0.30 to $0.50 each.

If you marry it with a cut-to-length spring and add the required pipe fittings you end up with a check valve that costs $2.

eBay - 1-1/2" Tire Stem Valve (TR414)	$4.14 for 10 ($0.41 each)
9663K85	302 Stainless Steel Cut-to-Length Compression Spring, 20" Length, .750" OD, .062" Wire Diameter = $5.42 (Cut a 2-inch section for $0.54)
4880K432  SCH40 White PVC Pipe Fitting, 3/4 Socket Female x 1/2 NPT Male, Reducing Adapter	$0.55 each x 2 = $1.10
2-inch long section of 3/4 SCH40 pipe = $?.??

The check valve design is great, but the only draw-back is that it looks like it would have a restrictive output. That issue inspired this, which is an updated version of DCHAP-1 with a scratch-built pump and a more normal grip and trigger.

The pump is inside-out. You move the outer tube over the plunger head and check valve in order to pump it. To accomplish this the M-F adapters and NPT coupler have to have their faceted sections sanded off.

I need to build and test the pump first. I'm not currently sure that the o-ring-based check valve on the plunger head will work. If it doesn't then I'll just stick another $2 check valve onto the end of the pump handle. The alternate course to take would be a ball pump.

Another item in the cards for this project is that I would like to make an adjustable over-pressure valve using the same parts.

Here's the part list for the above diagram.

http://www.captainslug.com/nerf/DCHAP-3.xlsx

Slotless Bullpup Snap (SBS) (Using this name until someone gives me a better one)

This is my entry for Aeromech’s homemades contest, which I think is super cool and good of him and Draconis to sponsor.

This design is almost entirely derivative of Aeromech’s PCSR (http://nerfhaven.com/forums/topic/26561-pcsr-a-new-homemade-design/),

I did take some other inspiration from Louiec3’s unnamed creation in the Homemades Picture thread: (http://nerfhaven.com/forums/topic/3861-homemades-picture-thread/page-20#entry280995),

Badwrench’s RSCB Longshot: (http://nerfhaven.com/forums/topic/17774-lstd-rscb-longshot/),

and all the various iterations and modifications of the Clothespin Trigger (CPT) by Carbon and others.

This blaster was created with several design goals in mind, specifically for newer nerfers:

• Pump–action priming method

• Achieve decent range (I don’t have a chrony, so this will be put to a comparable range test.)

• No slots in construction.

• Keep it Short

• Can be made with entirely or almost entirely parts from Lowes and/or similar stores commonplace throughout the USA****

• Can be made with a hacksaw, drill, files and knife alone. A dremel is recommended however.

So I guess I should explain these points. Truly, a first homemade should be along the lines of the Mark 8 Snapbow or Rork’s Snapbow Mk 5. Homemade Nerf Blasters really don’t get any simpler or easier than those.

However, what I wanted to achieve was a easy-to-build blaster that could be competitive with fancy-schmancy pump-action blasters on the field. This mandated having no slots (fuck that mess) and using mostly parts avaliable in my town (minus the seal and a k26* spring). I had most of these items on hand, and like most homemades, when you buy the materials for one, you have enough to build 5 with little extra cost. All this will be discussed at the end.

These lacking parts are regrettable, but a k26 is a useful standard, and I simply can’t find a rubber washer that seals in regular 1.25 pvc. If any of y’all have suggestions, please comment.

Anyway, on the blaster. READ FIRST BEFORE YOU ATTEMPT TO BUILD IT.

Materials You Will Need:

(hopefully got most of them)

Body:

• 1.25” sch 40. PVC

• 1” sch. 40 PVC

• ½” THINWALLL sch 40. PVC

• ½” sch 40. PVC

• One 1.25 - ½” sch 40. reducing tee

• One 1.25” sch 40. Tee (regular)

• Two 1” - ½” reducing bushings (I use the circular ones at Lowes though hexagonal ones can work with more packing tape)

• ½” copper repair coupling/section. THIS IS IMPORTANT. When finding this part, take the segment of ½” cpvc that you plan on using for the pump and find one that slides with as little resistance as possible.

• Packing tape

• Plumbers Goop or some other sealing adhesive.

Plunger Assembly:

• ½” PVC tee

• ½” PVC

• ½ CPVC

• 1/2" cpvc endcap flat

• Three ½” drywall anchors

• Three 1 ¼” OD washers

• ~6 ¾” OD washers

• 1 ⅜” rubber grommet (9307K81) (or some other sealing material)

• One 1.5” long pan screw

• Epoxy Putty

Clothespin Trigger

• A plastic clothespin

• Epoxy Putty

• ⅛” nails that are over an inch long.

• 1/4" screws, just cut them down with hefty pliers and/or dremel

Lower Receiver:

• 1.5” sch 40. PVC

• 1.25” sch 40. PVC

• Two 1” - ½” sch 40. Reducing bushings

• ½” THINWALL PVC

• 1/2" woodscrews

• ½” CPVC

• ½” sch. 40 PVC

Barrel Assembly:

• Two sections of 1-inch-long ½” PVC

• One normal ½” PVC tee

• ½” PVC

• One ¾” PVC ball valve

• One ¾” - ½” PVC reducing bushing

Tools You Will Need:

• A good hacksaw

• Drill with ⅛”, ¼” bit

• Hobby knife/files to debur stuff and make it look pretty.

• hammer

• screwdrivers

• Probably a hot glue gun if you fuck up somewhere

• RECOMMENDED: Dremel with sanding and cutting bits

• RECOMMENDED: big ass pipecutter to make cuts easy.

These seem like a lot, but it basically boils down your tools, epoxy putty + glue, some woodscrews, a 2’ section of 1.5” PVC, a 1” section of 1.25” PVC,

Body:

Let’s get to it:

Take your 1.25” pvc and cut a length of 10” and ~2.5”. Take the 10” piece and measure 4” from one end and drill a ⅛” hole. This is where the nail for the clothespin will go into the plunger tube. Make your clothespin trigger (CPT) and screw it into place. Here is mine attached:

You may want to run your drill bit around in there a bit for good measure and to ensure a loose-ish fit, BUT BE CAREFUL AND TEST FIT ALWAYS. For a better writeup/instructions, go here: http://nerfhaven.com/forums/topic/20274-the-clothespin-trigger/

Take this plunger tube/CPT assembly and glue it into the 1.25” PVC -> ½” tee. Be careful to align them the way you want. Plumber’s Goop probably works here.

Now let’s build the plunger rod/head. This is my method, but feel free to use other seals/catchfaces.

Take a 3.25” long piece of cpvc and ream out the inside to accept your drywall anchor. Screw it in (I also superglued it in for good measure).

I sandwiched the grommet mentioned earlier between two 1.25” od washers, with ¾” OD washers in between. Then I spaced it with #8 washers (ignore picture) and then another 1.25” washer before the drywall anchor. All this was screwed into the cpvc and then the catchface was built out of eputty and sanded down into a better shape. This isn’t super hard.

I then cut a spring spacer out of a piece of thinwall 1/2" pvc. Then I sleeved the spring on. It should be somewhat under precompression after the stock piece is made.

Cut the nail in the CPT down to appropriate length BY SMALL INCREMENTS AND TESTING. You should be able to push the plunger catchface into the nail and hear a “click” and be unable to push it forward. This is the second most important part of the build. For sake of not pulling the lower clothespin out of the blaster, I put a hairband around the trigger and body tube. It still catches without it, but helps keep it in place.

Let’s build the stock and spring rest.

Drill a ⅛” hole for your ¾” long screw into the center back of a 1.25” PVC tee. Ream out the inside of a <1” segment of ½” cpvc, then screw one of your drywall anchors inside it. Then screw the assembled spring spacer into the PVC tee. You may want to file/sand the end to help the spring slide freely.

Then cut a 3” long piece of 1” PVC pipe to act as a spring guide to prevent warping. Screw that into the tee as far as it can go inside. Then screw it into the body tube.

Moving on...

Now let’s build the front seal assembly and pump.

Take the smaller piece of 1.25” (the 2.5” one, jesus) and ream the interior ends so that you can push in the circular 1” reducing bushings into both sides. If you don’t have access to these, you can just use hex bushings and just glue them in. Then cut two ½” sections of the thinwall ½” PVC and glue it into the bushings ends. Ream out the insides and file it smooth. Then goop the bushings in on either side of the 1.25” segment.

Goop in a 2.5” segment of your ½” copper repair coupling into the thinwall ½” segments inside the 1” reducing bushings. It should slide through with some resistance. Make sure that it is flush with the internal “sealing end” inside the central 1.25” -> ½” tee.  When you cut the copper (presumably with a hacksaw or a pipecutter), be sure to ream out the end so whatever cpvc segment you are using can slide through with little resistance as possible.

Take the ½” cpvc segment and ream out the inside to allow the drywall anchor to be screwed in. I superglued it in for good measure. The drywall anchor will probably expand the outer diameter of the cpvc a bit, making it difficult to slide fully forward when priming. File it down should this occur.

Because of the weird spacing inside the tee, you’re going to have to expand the pump grip to ensure that the plunger seal is always inside the back body tube. I used several washers and a flat cpvc endcap to achieve this end. It is 1” long. Doubles as a stop to keep you from pulling the pump out of the blaster. Also, put in a rubber washer right before the 1/2" cpvc pump for added sealing. Probably unnecessary, but can't hurt. 

Once everything is dry, screw it into the “front” of the PVC redirect tee. Your main blaster assembly is done.

Now for the goddamn lower receiver. This is going to take some fine tuning.

Seriously, fuck this thing.

Cut a 2” and a 4.75” section of 1.5” PVC and then make halfpipes (or 60% pipes) out of them. The longer piece needs to be able to fit between the redirect tee and the CPT. These will clap to the body. Set them aside.

Cut two .5” segments of thinwall ½” pvc and sink them into two more 1” -> ½” reducing Bushings. Cut a 10” segment of 1.25” PVC, then sink both bushings into either end. One end can have a bushing flush with the pipe, while the other needs to be ~1” inside the tube. Also, add a handle.

Cut a 11.5” segment of ½” cpvc pipe and hammer a small bit of normal ½” PVC on one end. Ream the inside of this end heavily. I will explain later. I then put a crude trigger of elbows after inserting it through the receiver.

I lined up the 4.75” piece at the back of the 10” lower segment and screwed it in. Make sure it fits between the CPT and the redirect. Mark about 3.5” forward of the back halfpipe and then screw in the front 2” piece. Use short woodscrews here and bevel the holes so they can clamp to the body cleanly and without scratching the PVC to hell.  I then secured the trigger with another hair tie thing.

The reamed out cpvc and PVC should fit right over the lower half of the clothespin, and with a little force on the trigger, be able to push it down. I can’t explain it, other than it works. Fine tune it.

Assemble the blaster, lube it with your silicone, and screw the lower receiver to the FRONT sealing piece. Be sure to not puncture or alter the copper tube. Similarly, put screws into the same piece through the redirect tee. Also add a front handle by hammering on a stub of normal 1/2" pvc onto the cpvc. Then put on your 1/2" pvc tee. 

Put on a barrel and you’re good to go.

End notes:

• I was very rushed to finish this project and this writeup as I am leaving for NYC tomorrow morning. I will not have access to this blaster nor additional pictures.

• I know it’s ugly as shit. This looked way prettier in my head and implementation was mediocre at best. Someone on SNW thought that it looked “like a pipe bomb” and I really couldn’t disagree. The trigger mech works, though is hideous. Better implementations are necessary and needed.

• I had literally all of these materials lying around in my workshop. That said, I know many do not. Assuming its $4 for each 10’ section of piping, you’ll probably spend a fair bit on piping alone. (I used ½” cpvc, ½” pvc, ½” thinwall pvc, 1” pvc, 1.25” pvc, 1.5” pvc, plus maybe $10 in other fittings) Then you have epoxy putty, assorted ⅛” screws, the copper pipe, wood, k26 spring, grommets, etc. (<$50?) I’m sorry I don’t have a more exact price estimate. 

• If you buy materials for one, you have enough for probably 4 more with not too much more cost. Pretty cool. Alternatively, you can build other homemades in different designs.

• Range is a bit less than my Mega Double Rainbow and Rainbowpump. Considering it has a bit more than 6” of draw, it’s a bit lackluster. That said, it shoots through Nerf-brand cardboard with ancient 1-bb hotglue dome stefans. I think it’s okay.

• I’m using an RSCB because I like the low profile. It hops fine. Don’t flame me Van.

• The cpvc priming arm does flex a bit, and this can be improved by hotgluing a wooden dowel rod down the pipe. You could also used ½” copper pipe. I will probably do this in the future and edit the OP to accommodate.

• The pictures are bad and some of the parts are filthy. The first Eputty ramp was not mixed correctly, had the consistency of playdough, and disintegrated in the plunger tube. It honestly just needs to be washed. 

• I have run maybe a hundred shots though this thing. It seems to work okay. 

• EDIT, thank you Snoop. This blaster is rather heavy, though I really don't think this is a big deal. Weight can easily be taken off though better/slimmer implementation of the lower receiver. 

Yeah, I think I’m done. Please comment, add input below.

Plusbow Rev.3 Guide

Instructables Mirror

Design Goals

• Reduce Part count
• Two Options for Plunger tubes and Plungers (+bow or 2-11)
• Omni-directional catch
• Spring guide to remove "serpentine" behavior
• Ease of dis-assembly
• Limit screws to two lengths (1/2" and 1-1/2")
• "Check Valve" Plunger head
• Use of extension springs or rubber bands for catch (multiple configurations possible)
• "Ultra-Compressible" O-Rings
• NO MORE INTERNAL CUTS, that means no pilot holes, no feeding a scroll saw blade through a pilot hole. Every cut can be done with a scroll saw or a band saw.

Total Build cost: $70 (for one plunger tube type)

Sunk Cost per Plusbow: $25

Thanks to: Splitlip, Aeromech, Ryan McNumbers, Groove, CrankyMonkey, VACC, and TED