McMaster is very user friendly and it's easy to find things if you look.

Thank you for answering that. The plunger head on this ended up breaking during APOC so I will definitely be revising this design.

Apologies to Aeromech for using his thread to promote my wares.

I'm going to be buying from you in a few days anyway so I don't mind at all. I'm told thinwall PVC is excellent for pumps. But I have NEVER seen it in any hardware store so typically I assume it doesn't exist for the sake of having a universally accepted writeup.

Please ignore the messiness of my den/workshop/sex dungeon. Stampede is double-volted with alkaline batteries, and has a slightly shortened BBB spring inside. Trigger is hooked up to one of the brake handles. Sledgefire pistol sits on the other side.

It could look cleaner but that would involve drilling into my fucking bike.

Video up tomorrow.

I'm not really an authority on the matter, but here's the guide on how to do it. I've read it and want to host one myself in the near future.

May not be a bad idea to get in contact with the previous host too.

Wow guys, sweet war, really.

I guess we're doing the pros/cons thing?

Pros
-Langley runs pretty baller wars.
-Meeting new and old people that partake in this geeky hobby.
-Seeing all the different flavors of homemades. Really, your soul goes into those things. It's heartwarming to see everybody's creativity.
-Finding another Long Island based Nerfer.
-Got rid of some old stuff I don't use.
-Even the "noobs" had a good run, everybody was pretty lax about loaning blasters and parts to those less-armed.
-Weather wasn't that bad
-Signing the shit-ploy. You could easily ebay that for like 75 cents now.

Cons, (Not really, just funny shit that happened.)
-Realizing you're out of ammo three feet away from DX.
-Gotta get me one of them there rocket launchers.
-SNAP style blaster deciding to eat a dick in the last round.
-Motherfucking New York City traffic

10/10 would apocalypse again.

I have some 3/4 PVC pipes laying around I can make a couple dicks sticks for the carpe rounds. And they will be absolutely fabulous.

Being shot in the side of the head from 5-6 feet away is not fun.

So long as it's a swiping motion, and not the "fixed bayonets" linear stab, I do not mind barrel tapping. That being said, no exposed metal.

Check out the supa sub-optimal writeup!

Inquiries and Responses

Do you worry about face diddle from the plunger rod? Also, I think you could substitute cutting board from Ikea or Walmart for polycarbonate. For the plunger rod, MIG has a great design for a omnidirectional plunger rod using 1/2 pex and drywall anchors.

So long as you keep your face on the pool noodle you'll be fine. It's really comfy.

As for the cutting board rainbow catch, I want to try this out but I wanted a functional entry for the contest. I will certainly be experimenting with cutting board catches in the future, as it is much easier to work with than polycarbonate. MIG made his catch out of it and it seems to be holding up in his multiple orgasm.

As for the PEX tubing, this would require a different inner diameter of the catch mechanism as 1/2" PEX is not really 1/2" in diameter. I do have some PEX laying around and I would be remiss not to give it a shot in the future. I'd like to see how wood dowels hold up as well.

...aside from nylon rod, what do you think would work as the plunger rod?

Dunno. Still working that part out. My eventual goal is to get a model working that is completely independent of McMaster.

Any sort of long skinny thing would work. I've used CPVC successfully. Pex can work, but I've had slight problems with keeping the flexible stuff straight. Some people have used wood, but I haven't done anything with it before, I imagine it would crack.

1/2" CPVC is not really 1/2" in diameter, so I'm scratching that of the list for the time being. Also I find it to be rather brittle. I've seen CPVC stuff break first hand. I'd like to try a wooden dowel first, with the ends braced with metal, perhaps tapping into place a section of brass tube right behind the plunger head. The brass ring would absorb the "splitting force" from the plunger head rushing forward, as opposed to the wood itself.

The blaster that this is loosely based on uses CPVC for the plunger rod. The omnidirectional catch is formed from a gap in the CPVC that is bridged by an oak dowel rod. The oak is nested inside of an aluminum tube, that nests in the CPVC. This provides a little more surface area for the catch pin to rest against.

Thank you for the insight. I imagine this setup would also work with a rainbow catch. If my dowel design fails, I'll have to try this and ream out the catch mechanism to fit a larger diameter plunger rod. Not the end of the world, but it is one more step involving filing.


Good advice everybody. Like I mentioned, I am not a SNAP builder so every bit matters.

Rainbow in a SNAP

It uses a rainbow catch, so technically it's a plusbow class but really it should be SNAP class; can be built in a day and uses many parts available at hardware stores.

Preface
SNAP and Rainbow style blasters are two of the most common blasters in the homemade realm. SNAPs can be built in the course of a few hours, but have been known to be tricky for beginners to get working reliably. Rainbows are reliable and streamlined, but require some parts to be purchased from outside retailers like McMaster-Carr. This writeup attempts to address some of the limitations of each blaster

Additionally, while maintaining this as an entry in the Noob's First Homemade Contest, I would like to open up the Rainbow style of blaster to those users that make SNAPs by reducing the amount of materials needed from supply companies.


Previously on 24
CaptainSlug creates an adhesive free blaster with the Plus-bow
Carbon's SNAP Blaster gains popularity for it's ease of assembly and readily available parts
Rork creates the Superlative Plunger Head
The Rainbow clan creates the Rainbow Catch, my personal favorite blaster style.
Langley builds a super sexy SNAP Rev 5 that makes me feel all giggly inside. Still, I want something with a little more ass than a SNAP...
Spiderbite makes raw materials accesible to the masses.


Build Goals
Decrease the amount of material needed to be purchased from McMaster-Carr, or comparable vendors
Decrease build time compared to a traditional Rainbow-pump
Allow for either traditional pull-back or Pump action operation
Eliminate the use of slots entirely
Eliminate the use of adhesives in the body
Reduce cost compared to a traditional Rainbow pump, and use materials familiar to SNAP builders


Tools
Saw
Screwdriver
Drill with bits
Course file
Rat Tail File
1-1/2" Hole Saw
Rubber Mallet
6-32 Tap
8-32 Tap
Tap Wrench
Masking Tape
Sharpie
Knife
Countersink
Pliers
Hot Glue Gun
Table Vice


Consumables
Plunger Head
1-1/4" steel fender washer
1-1/4" rubber/neoprene fender washer
1-1/2" rubber/neoprene fender washer
#8 finishing washer
8-32 x 1-1/2" pan head machine screw
Electrical Tape
Lithium grease or silicone grease

Plunger Rod
1/2" Nylon Rod from McMaster
8-32 x 2-1/2" machine screw
8-32 x 1-1/4" machine screw
1/4" nylon tubing
3/4" x 2-3/4" x 1/4" polycarbonate from McMaster
#8 washer

Body and Catch
1-1/4" PVC
1/2" to 1" PVC bushing
1/4" Polycarbonate from McMaster
1/4" OD compression spring
#6 x 3/4" machine screws
#6 x 1/2" pan head machine screws
[k26] Compression Spring from McMaster

Stock and Trigger
1" x 5" Pine Board
Cutting Board
8-32 x 1-1/2" machine screws
6-32 x 1-1/2" machine screw
#10 x 1" Wood Screws
#10 x 1/2" Wood Screws
3/4" PVC
Pool Noodle
Rubber Band
Elmer's Glue
Hot Glue

Forward Pump
2" Polyester Tube from McMaster
Cutting Board
6-32 x 1/2" machine screws
Skateboard Tape


Let's Begin. Descriptions will be underneath their respective photos. Put on your safety goggles now.

Plunger rod assembly


We'll start with making the superlative plunger head. Align the materials as shown, with the rounded side of the finishing washer pushing against the rubber washers.


Should look like this when it's all assembled on the screw.


Cut a 3" length of the nylon rod.


Drill and tap the center of the nylon rod, about 1-1/4" deep


Screw the plunger head assembly onto the nylon rod. Tighten it down so the finishing washer squishes against the rubber washer, as shown. It will freak you out the first time but this is supposed to happen.


Drill and tap the other end of the nylon rod for 8-32 screws, about 1" deep. Make sure the hole is centered.


Screw in the 8-32 x 2-1/2" screw until this amount is peeking out.


Cut off the head of the screw with your hacksaw. Slide a 3/4" length of the 1/4" nylon tubing over the screw.


Use the knife to cut a bevel on the end of the nylon rod. Be patient, nylon is a pain to work with, but a sharp knife and caution will get it done.


Cut another 10 inches of nylon rod and drill and tap BOTH ends for 8-32 screws, about 1-1/4" deep.


Put a VERY GENTLE bevel on the rear part of the nylon rod, and screw the two parts together as shown.

This type of plunger rod is known as an omnidirectional plunger rod.


Rainbow Catch

Using the Hole saw, cut out 3 of these holes from the polycarbonate plate.


On all three disks, drill out the hole with a 1/2" drill bit.


File out the inside of each disk slightly with the rat tail file.


On two of the disks, drill out two holes with a 7/64" drill bit, as shown. The left disk has a cross of holes drilled into the disk itself. Drill these out with a 7/64" drill bit. On all of these holes, tap with a 6-32 tap. Here are the templates hosted by Daniel Beaver if you need them. I don't use 'em anymore.


Here is the middle part of the catch mechanism. To make this piece, saw off the two sides, and then file down one of the round edges. Then, tap and drill the thinner round side for a 6-32 screw.


Using a rat tail file, put a gentle bevel on the hole in the front outer catch plate, as shown. This is to allow the back part of the plunger rod to clear the catch easily.

NEED ONE MORE PHOTO OF THE COMPLETED CATCH


Preparing the Body Tube

Take the catch assembly with the drilled plate in the front, and mark off points on the PVC that meet up with the four drilled holes. Extend these lines straight a few inches.


Make a mark 2-3/4" from the rear of the tube, and wrap tape around the tube, with the ends of the tape aligning to create a straight line around the tube. Trace around the tape with a sharpie.


At the points of intersection, drill with a 7/64" drill bit, then countersink to allow the 6-32" x 1/2" pan headed screws to be inserted later.


Draw a line in between two of the lines previously drawn, and mark off points 1/2" apart. Drill out these points with a 1/8" drill bit. This is the bottom of the cylinder.


On the side opposite the holes that were just drilled, drill 1/2" holes to allow the wood screws to be inserted into the 1/8" holes from the top.

In front of the assembly holes and the catch, drill two 1/2" holes into the body tube. These are called speed holes, and allow air to enter the tube behind the plunger. This is so a vacuum does not form behind the plunger head.


Insert the entire rainbow catch into the tube, with the heads of the screws facing the back, and the tapped side of the small plate facing the bottom of the body tube.


Line up the tapped holes in the polycarbonate plate with the holes drilled into the PVC tube. Insert the 6-32 x 1/2" pan headed screws into these holes to secure the catch.


Drill a 9/64" hole 1/4" behind the screws that were just inserted, as shown. This hole is where the 6-32 x 3/4" screw will be inserted.


Sheath a small piece of the compression spring over the 6-32 x 3/4" screw, and screw this screw into the previously drilled hole until the screw catches the tapped out part of the center piece of the rainbow catch.


The Stock

Cut a 15" section of the 1" x 5" pine board. These dimensions are accurate except for the 1.5" dimension, that should be more like 2".


Cut out a 1/2" deep section about 2-1/2" long. This is where the body tube will meet the stock.


Align the body tube with the back of the depression at the top of the stock. Mark the points where the holes on the bottom would meet the stock.


Mark a line down the center of the depression of the stock. Where the marked points meet this line, drill out these points with a 1/8" drill bit about 1" deep.


Here's the easy way to make the stock shape. Cut out a hole in the stock with your hole saw where the web of your hand will rest. In the photo, pencil lines are visible. Now instead of making complex cuts using a scroll saw, just cut two straight lines with your regular old hacksaw and save yourself 200 bucks. Then clean up around the handle with a file.


Screw the stock onto the body tube with the wood screws. Those holes on the top made in the previous step allow this to happen, as shown in the photo. Put the 1" long screws in the front 2 holes, and the 1/2" long screws in the rear hole.


Inserting the Bushing

Wrap the PVC bushing in 3 or 4 wraps of electrical tape. Make sure it is wrapped tightly.


Use a rubber mallet to smash that shit into a 14-1/4" section of 1-1/4" PVC


Measure 15/16" from the edge of the 1-1/4" PVC and mark this point.


Wrap the masking tape around the PVC tube, ensuring the ends of the tape align. This means that a straight line is created around the PVC tube. Draw a line around the tube at the edge of the tape with the sharpie.


When the tape is removed, a straight line is revealed. Next, we will mark where the screws will be inserted into points on this line. Mark a notch on this line where two opposite corners of the bushing exist, as shown. Then, mark a point at the center of the side of the bushing 90 degrees offset from the original mark, on each side. This will result in four marks each 90 degrees apart on the cylinder.


Drill and countersink the hole with a 7/64" drill bit and a countersink.

Remove the bushing. We will be putting it right back in, but now everything is prepared.


Assembly

Put all kinds of grease on that plunger head. I just used lithium grease because it's what I had available, but I usually use silicone grease. Also slip your [k26] spring over the plunger rod assembly. Insert the assembly from the front.


Push the rod all the way down the tube. You will have to depress the catch to allow the plunger to go all the way back.


Re-insert the bushing, and screw it in place with four 6-32 x 1/2" pan head machine screws.


cut out a piece of polycarbonate about 5/8" x 2-1/8" This is the only other point where polycarbonate is needed. Sand down the edges of the polycarbonate.


Place the polycarbonate plate against the end of the plunger rod. Mark a dot on the polycarbonate where the drilled hole in the plunger rod lines up with the center of the plate.


Drill and tap this marked point with a 1/8" drill bit and 8-32 tap.


Screw the polycarbonate into the plunger rod with an 8-32 x 1-1/2" screw and a #8 washer. Prevent the rod by rotating by clamping the plunger rod with a set of pliers.


The Trigger

Take your cutting board and cut out two segments, 3/4" x 7".


Bevel out one edge about 4" down.


Repeat on the other side so the 2 bevels are "facing" each other.


This is to allow the cutting board to hug the rounded edge of the body tube.


Secure the two cutting board plates against the body with some extremely erotic duct tape.


Drill and countersink two holes through the two plates and the wood with a 1/8" drill bit.


Drill through the front of the two plates. This will serve as the rotation point of the trigger. Countersink this hole too if you feel so inclined.


The two plates secured. Now back out the screws a bit to free the plate on the opposite side. It will make installing the trigger easier.


Cut out a square of cutting board about 2". Mark out approximately where the cuts will be made. We want a depression behind the point of rotation to allow the rainbow catch screw to protrude a bit, and a rounded back so nothing gets caught against the handle.


This is my final shape. I used a total of four #6 washers to center the trigger.


Drill another 1/8" hole through the two plates and the wood. The cutting board is not very sturdy, so this extra screw prevents deflection of the cutting board. Just drill all the way through. Then screw everything together including the opposite side plate.


Drill a 9/64" hole in the middle-rear of the trigger. Insert a rubber band through the hole.


Insert a 6-32 x 1/2" pan head screw on both sides of the plates right above the rubber band. and loop the rubber band around both of the screws. This will yield a semi-retained trigger.


Shit's starting to look like an actual blaster.

Finishing Touches

Take 2 pieces of 3/4" PVC one 4-1/2" and one 3". Pre-drill the wood and countersink the PVC. Then screw in the 1" wood screws to secure the PVC into the wood.


This is where that pool noodle comes in. Cut out two 3" sections of pool noodle and cut out a small notch in each, as shown.


Use hot glue to secure the pool noodle onto the PVC. It's supa comfy.

OK, so if you stop right here the blaster is fully functional as a traditional pull-back. The next section will turn this into a super effeminate pump action blaster.


Pump Action

Cut out a 17-1/2" piece of 2" Polyester tube.


Slide the tube onto the blaster, and mark where the tube meets the cutting board plates on each side. This will reveal how wide the pump channel needs to be.


Extend these marks down the length of the tube, about 11-1/2" deep. Mark these measurements off as shown The piece with the X's is the part to be removed.


Drill 1/2" holes at the corners of the box created in the previous step. This is because a round edge has a far lower stress concentration than a sharp 90 degree corner, and will decrease the likelihood of failure in the event of an unexpected impact.


Cut down the channel with your hacksaw. Then cut across the top of the cut. Pry this strip of material out to make your pump channel.


Bam.


Now repeat this procedure on the top side of the tube to allow for clearance for your hopper or barrel attachments later on. Only needs to be about three inches deep.


To recap, the really long cut is made on the bottom rear, and this short cut is made on the top front of the tube.


Give it a test fit. Now we just need to make a retention piece.


Trace out the inside of the rear of the Polyester tube onto a piece of cutting board.


Cut and file out the cutting board piece until it fits snuggly in the Polyester tube.


Mark out the approximate center of the "circle" and drill this point out with the 1/2" drill bit.


Cut the hole with a saw. Widen everything out with the rat tail file. This part will ride over the plunger rod, so it should be pretty loose.


Slide the pump onto the blaster, and insert the retention piece over the plunger rod, flush with the end of the Polyester tube.


Drill through the polyester tube into the cutting board retention piece. Be careful not to drill into the plunger rod. Drill on both of the sides, and the top. Then countersink these holes. Screw in three 6-32 x 1/2" pan head screws to assemble the pump.


Push the pump all the way forward. Note where the pump covers the speed holes in the body. Drill a hole in the pump over each of the speed holes to allow air to flow freely into the speed holes.


Wouldn't be an Aeromech build without skateboard tape.


Finished Blaster

Final assembly is 31" without barrel assembly.


Pump dat action


Ready to launch


Results
-Blaster shoots about as hard as anything else I've made. Has yet to be war tested, though Apoc will change that.
-The only things needed from McMaster are the nylon rod, polycarbonate, [k26], and Polyester. SNAP builders may even have replacements for these that I am unaware of.
-Can be fired as a pull back or pump action.
-No slots were used.
-No adhesives used in the main blaster.
-Most parts come from Ace Hardware locally.


Discussion
This writeup uses an omnidirectional catch and plunger rod, though a unidirectional rod would actually work, as the top face of the stock acts as a stabilizing face against the pull back mar of the plunger rod.

This build is meant for two audiences. Primarily, for those new to building homemades that want something more than a SNAP. I consider myself pretty new to this area of the hobby, as six months ago I would have no idea how to build a homemade. The SNAP is riddled with durability problems, and the rainbow solves them, it's as simple as that.

The second audience would be current SNAP builders. Somehow, SNAP builders have gotten access to [k26] springs or equivalent, and the only thing holding them back following this build guide is a few square inches of polycarbonate and maybe the nylon rod, but I feel like SNAP builders have already found something equivalent. I would love to have SNAP builders chime in and tell me what they've been using for supplies and what they think about this design, as I am not a SNAP builder. Following this writeup, a SNAP builder could go to a war and arrange to buy a Rainbow catch and some nylon from a Rainbow builder. Or hell, Spiderbite has sweet deals on this stuff now, so there's really no reason not to Rainbow.


Size comparison with my Rainbow pump

Philosophy aside, this is a pretty cool blaster and I achieved all of my design goals with it. Shoots well, and feels pretty good too. And it's lighter than my Rainbow Pump. Also this could easily be built in the course of a day, maybe eight hours.


Here's your porn.

Fire away.

Excellent. I'll be bringing 2 extra humans that nerf as well as my entire arsenal. Now show me what this New England Nerf scene is all about.

My pull-back priming disk.


Reverse-porn shot. I make my Rainbow pistols with omnidirectional catches and a round plunger rod, so this type of pull-back-disk is ideal. There is no wrong way to orient this disc, because, obviously, it's circular.

I like this because it doesn't require one to buy another part to make the pull-back mechanism, just make one more hole-saw cut into the polycarbonate plate you were already using to make the rainbow catch. Plus, I think it looks classy as hell. Not that I am not incredibly aroused by that ball knob...

I'm just concerned how well that will hold together.

This also has the added benefit of a flat plane contacting a flat plane; the flat pull-back-dick is held fast against the flat surface of the end of the plunger rod. This is opposed to a rounded surface against the flat surface of the end of the plunger rod, leading to the priming ball potentially being sheared off. Nearly this exact situation has actually happened to me. No matter what you do, there will be some kind of a moment on that part.

I believe Captain slug used electrical tape and screws to fasten down his bushings. He was very proud of using no adhesives, (As he should be.)

Here is the writeup. Steps 2 through 8 appear to be relevant.

EDIT: Fixed the link.

God that is sexy. I love my rainbow pistol and your method of assembly is really nice; hitherto I have slid in the internal components from the rear with a pre-installed front bushing. I will try this method next time I make one. Very lucid and detailed writeup.

The spectre is a revolver type blaster. Because of this, there is a gap between the rear of the barrel and the firing mechanisms, i.e. the plungertube. The air coming out of the plungertube will ALWAYS take the path of least resistance. So when you have a very tight dart fit in your barrel, the air rushes out of the gap instead. If this was a nightfinder (or whatever nitefinder clone they're putting out these days,) a tighter barrel fit would probably be OK. But because of this barrel gap, just be wary of using barrels that are too tight.

The progression of my rainbows. Number 3 on the bottom with the super effeminate floral pattern. The two on top are number 4's. More refined and easier to produce than number 3's. Damn near perfect seal on all of 'em.





Double Rainbow and Laser Pistol. I am super proud of both. Especially the Meriflage.

You have to look at problems that current designs have and imagine something that would solve that.

If you have yet to make a homemade blaster, try making a snap or rainbow or something. Take note of where you went, "Wow that took a lot of time to fabricate," or, "Gee, that looks kind of flimsy." You know, things like that.

Pretty much make sure you possess the propensity to construct a homemade before trying to revolutionize the game. Not to put down your mechanical abilities, which I have no knowledge of, but I can tell you that my first rainbow was kinda pretty supa crappy compared to the ones I make now and I was modding for maybe three years prior to that. Try it out and see what you think before you go blowing cash on supplies and tools.

Always use that search function. And check out the Noob's First Homemade thread to get you started.

Good luck, bro.

Pictures would help

Please do this.

Make sure that all the little springs are in their place and haven't popped out. Also check to make sure the locks Hasbro has in there aren't interfering with operation.

The internals directory is super useful for determining if something is mucked up on the inside of your shiny toy. Take a good look at the Longshot internals.

Sick war, everybody, will definitely be there next time. Great to see new faces (new for me at least) and testing out my laser pistol.

Thanks Langley, Jlego for letting me know how to make wyes like a proper baller.

Is the attendee list still valid for the new date? I'm still going and I even have a plus one.

See ya at NENO!

Well since that just changed put me down aas 1000000% definite.

Will be bringing at least one guest, too.

Darn, I'm already committed to a war on the 5th. As much as I'd rather come to this, it would be unfair to them.

I'm in the same boat, DX. I would love to come to this, but Nerf wars aren't built on maybes. See ya at NENO!

Also, get this ish on the 2014 Nerf War schedule!

With your permission, I'll post a pic of them here. I bet your doors adapted onto PETG shingles will be a pretty big win.

Please do.

This is nice because when you need to reload the plastic arm can be pushed out of the way real easily. The curve of the 1/2" PVC then makes it spring back to a straight semi-cylindrical shape.

I'm looking around for a material that holds it's shape a little better than the milk jug plastic for the foot of the arm. My next attempt will be using a BBQ lighter to melt the plastic into the bent position.

I'll be putting up a video as soon as I can. They work surprisingly well. Once I find an adequate pouch I'll be making a video.

Not enough sidearm love. Pretty effeminate Rainbow pistol right here.

Preface

Running around in the woods at the most recent NJ Nerf Outing I noticed a pattern in my actions: Run up, dump a clip, run back, reload, repeat. This may be a problem inherent to my play style, but the problem encountered is the constant need to reload and the inability to do so quickly. This simple mod using materials most people already have attempts to solve the problem. Inspired by the hopper/magazine system used on the Madsen LMG.

Sort-of-Writeup


A few of you master builders probably already see how this works. For everybody else, here's the low down.


Take your desired length(s) of 1/2 PVC and cap them off. You can even use the usual ball valve set up if you like carrying heavy things in your pocket.


This is a piece of plastic milk carton (Canadians be jealous, eh?) Cut a strip out maybe nine inches and fold over the last few inches. This increases rigidity. Fold that portion in half to make a 45 degree bend inward, as shown.


Tape it to the end of your clip so the bent tooth blocks off the "exit" of the clip. The extra few inches of non-taped area allow the plastic arm to flex. These next super erotic photos will explain the function.


When at rest, the plastic arm holds the darts in place inside the clip.


Upon initial entry, the arm is pushed aside by the PVC wye.


When the clip is fully inserted, the arm is pushed all the way to the outside of the wye, and the darts flow freely.


Here it is on a rainbowpump. The black/gray stuff on top is skateboard tape. You're gonna have to twist these off when your done, so I find it gives you extra grip. Plus I already skate so it was within arms' length of my bench. You can see it on the rainbowpump as well.

Results
I have not war tested this, so I don't want to be overly confident about this. But it works just as well as any other hopper and the darts do not shake out. Plus these are easy as hell to make. Took me like two minutes. And now, as suggested before, you can easily carry like five of these in a pouch or cargo pocket. Hell, you can probably make these snap into PVC couplers cut in half and carry them Mass Effect style.



Rip me apart, boys and girls.

You should begin the writeup with an overview of the blaster and its operation, followed by a part build of the major components, grouped in order of how important each component is (aka the plunger rod is what almost everyone puts first, but is in fact one of the things that matter least).

This makes these weird tube blasters much easier to understand as each piece now has a context. This was a mistake I made in almost all of my writeups, realizing only now as everyone else's is quite inscrutable.

Zorn, when I have the time (probably not til Friday with these damned summer classes) I'll throw up some sketches. I know what you mean though it took me a while to figure out how the FAL series worked.

Nice concept.

I've found that with larger diameter plunger tubes, in order to compensate for the increased volume being forced out, a stronger spring is needed other than a [k26]. The reason it seems to output less 'power', is because the plunger rod stops accelerating forward sooner, due to the increased volume its trying to push out of a 1/2" diameter hole. The power comes from the acceleration. In essence, the plunger rod reaches a terminal velocity sooner in a larger plunger tube than it would in a smaller diameter one when using a [k26].

As for the mass of your plunger rod assembly. The 2 polycarb disks you used are not necessary. Or at least ones that big. The drain plug is pretty sturdy and really only needs support from behind. Using a decent sized washer behind and a smaller one in front is all you need.

If you wanted or expected the overall length to be decreased by this design, the key is in the length of the plunger rod. The only way to decrease the length of a blaster (while maintaining your expected draw length) is to decrease the length of the effective plunger rod. In my MO, I did this by creating a section in the 'G-spot' that sleeved what would be the tail end of the plunger rod. Effectively decreasing the length of the plunger rod by the total length of the compressed spring length. In your case, you could shorten the plunger rod (and overall blaster length) by 5.5".

The polycarbonate discs are artifacts of my experience with skirt seals. I will try this method you suggest before my new skirt seal arrives.



Here is my original sketch of the design. If you can see the telescoping plunger rod was stolen lovingly eloped with this design. However, my fear of omnidirectional rods got the better of me. Having taken a closer look at the catch problems I was having with those, I think I figured out what I was doing wrong. I am actually quite happy with the length it is now, I may change this in a future design.

Anyway, the blaster I have now works with my "A2 Lower" design of lower receivers for the blaster. In short it's a system I use that allows interchangeability between the Rainbow type blasters I produce.

...this type of design just isn't as efficient as the more basic pump action types of homemades.

Tell me about it. My next design follows a RBP more closely, those are rock solid.

What I have found with my expand a blast, which has the same problems as your homemade does with the power, is to not make the seal perfect. Doing this reduces friction, which I have found adds enough speed to the plunger rod to counteract the loss of volume and actually add extra power.

Your words make sense, but that air seal is so damn effeminate... If I must I shall, but not without exploring my other options first.

While I've done some relevant work with large plunger diameters in the BullPAC series, I don't recall making a blaster called the FAL-1, so I think you've misattributed credit. Also, if possible it's nice to link to the blaster threads rather than just mention the names, although I often forgo this when finding the threads is difficult or if I'm feeling lazy at the time.

Regarding barrels, since the larger PT produces a lower pressure but greater air flow rate (given equal priming force) you may have better results with an all-loose barrel, or at least a partly loose barrel. This in part depends on your plunger speed, so your heavy plunger head may necessitate a tight barrel, but since you are working to reduce your plunger mass I thought this might be relevant.

Fixed the writeup to reflect this. It was Zorn's creation I meant to reference.

I'm looking into the "Telescoping Barrel" idea, with a tight fit initially, and a loose one after a few inches. That being said, I'm going to see if I can get away with shotgunning this thing. Low pressure/high volume leads me to believe I may be able to throw on a 1 to 4 coupler on the end, and fire off 4 stefans from short barrels.

Preface
Sketching/drafting is one of my favorite time killing activities, and my mind inevitably wanders to Nerf related things. I got to performing some calculations, and realized that using the 2" PETG as a plunger tube instead of 1 1/4" PVC yields a 61% increase in cross sectional area in the plunger tube. That's resulting from a diameter increase of only 27%! At this point I was hooked on the idea, and despite the known problems with this design, I decided to give it a shot anyway. Inspiration draws from a wide variety of sources, initially Zorn's FAL-1, MIG's Multiple Orgasm, with the final product (I suspect) more similar to Nine's ART.
Read results at the bottom before you decide to build this one.

In this writeup, photos are above the reference text.

Consumables
1-1/4 to 1/2" PVC bushing
1 to 1/2" PVC bushing
2" OD PETG*
1-1/4 Clear PVC*
8-32 x 2" Machine Screw
6-32 x 1/2" pan head screws
6-32 x 3/4" machine screws
1-1/4 PVC Tee
2" PVC
1/2" PVC
1/2" PVC endcap
1/4" thick Polycarbonate*
11" long [k26] spring or stronger*
1-5/8" Bath plug
1/2" PVC Insulation Foam
3-16" Light Duty Rope
Packaging tape
Plumber's Goop
Silicone Grease
Catch spring

Tools
Course File
Rat Tail File
Drill with Drill bits set
Permanent Marker
Ruler
Screwdriver
Hacksaw
Vice
6-32 Tap
8-32 Tap
1-1/2" hole saw
1-3/8" hole saw
1/2" Countersink
1/2" Nylon rod
Table Sander
Trusty Knife
Rotary Tool with cutting bit (optional)

Note: (*) indicates this item was purchased from McMaster-Carr.


Plunger Head


I could have bought a skirt seal from McMaster Carr, and I probably should have. But for the sake of spontaneity, I picked this up instead from Ace Hardware. If you do this, I reccomend getting a skirt seal, it will probably save you a lot of weight in the plunger tube. I will likely swap out this part in the future.


You know what to do.


Your finished plunger head should resemble this guy. I put the bath plug to a belt sander to trim down the height a bit. The idea was to reduce the weight of the plug, as it is made of a very dense rubber type of material. It is very rigid and I am confident it will not break. I used polycarbonate cut using a 1-1/2" holesaw to make my "sandwich" here, but you can use washers if you like. This was my attempt to keep the already heavy plunger head to a minimum. Throw an 8-32 x 2" Screw in there to attach it to the plunger rod later.


The Catch

Make one of these. Standard Rainbow Catch. I don't even use Templates anymore. Just use a holesaw. Make an extra "endplate," as shown next to the catch assembly.


Plunger Rod


Tap that rod with the 8-32 Tap. This material I've found is notoriously difficult to self-tap, and even tapped, it's tough to screw in the plunger head.


Make yourself a catch Notch. Make the notch longer than the one pictured. I was having catch issues due to this notch being too short lengthwise. The catch face should be about 7 inches from the rear of the plunger head assembly, as shown.


Drill a 5/16 hole about an inch from the rear of the plunger rod. Tough to see here. We'll come back to this later.

Rear Bushing


This part is made by connecting together a 1/2" PVC endcap, a 1/2 to 1" PVC bushing, and just enough 1/2" PVC to connect the two pieces flush.


Round off the protruding edges using a file or belt sander. Also shown is a big hole in the back of the endcap. Make it happen.


Wrap it in tape as if you are making a traditional Rainbow, so that the part is a relatively tight fit. Doesn't need to be airtight.


When inserted into the 1-1/4" PVC, this part should not interfere with the interface of the PVC and the PVC Tee which will make up the stock.


The Body


I like to blueprint my parts.


The easy way to make slots. The rear bushing we made before will support both halves of the split tube. Forget all that drilling nonsense. Just keep the slots about 1/2" thick.


Make 'em look pretty. File flat the slots.


Here is everything assembled in the body tube. A lot of things happening at once... I'll give you the measurements in the morning, but basically, the front of the blaster is the right side. The spring rests on the free-standing plate on the right. The assembly on the left is obviously the catch. The little piece of gray/black material is some of insulation foam used to cushion the travel of the pump.


Throw some speed holes on there. Seriously, they work.


Plunger Tube


Take the 1-1/4 to 1/2 bushing and wrap it in packaging tape until a tight fit in the 2" PETG. Secure with Plumber's Goop inside the tube and allow it to dry overnight. Drill, tap, and countersink holes for the 1/2" screws.


The plunger tube needs a slot on the bottom to allow the rainbow catch screw to clear. Make on about 3/8" and 8" long.


Here it is on the body tube.


Make two of these parts, about 2 inches wide and 1 inch tall. The purpose of these parts is to resist rotation. Take one of these parts and Size them so it just fits inside the 2" PETG Plunger Tube. When the PETG tube is screwed onto the wings of this part, the wings will fit right inside the slot on each side, and the 1/2" hole in the middle will allow the plunger tube to slide right through it. This prevents the Plunger Tube from rotating all over the place, and also provides a linear constraint on how far the plunger tube can be pushed forward.


Screw in the winged part to the rear of the PETG tube from both sides. Tap it into the PVC, and countersink. Secure with Pan-head screws. You are NOT screwing into the plunger rod here, this part is meant to slide over the plunger rod.


Here is the winged part in the blaster, underneath the screw.


Here it is again. Remember this part is united with the plunger tube, and is meant to slide over the plunger rod.


Take the SECOND winged part and screw it into the plunger rod. Make sure the rod is oriented with the catch notch facing up, so the catch works properly. Again, THE WINGS INTERFACE WITH THE SLOTS, PREVENTING ROTATION. I secured this part by drilling a 3/8" hole into the plunger tube, drilling a 7/64 screw into the part and rod, and then screwing in a 6-32 machine screw, as shown.


Low Profile Plunger-Stop


Take your Ace Hardware Rope and string a 2-3 foot length through the hole in the rear of the plunger rod. Drill another hole on the underside of the body tube to get it in.


You see where I'm going with this. That large hole drilled in the rear bushing is to assist in the positioning of the rope.


Drill a hole in the top and bottom of the endcap. Thread each side of the rope through the hole and tie it off. To get the right length, you'll need to fire the thing a few times, and tie off both ends. Drill and countersink the rear bushing into the body tube using two of the pan headed screws, one on the top, and one on the bottom.


Lower Receiver


If this doesn't make sense, just follow along, it's pretty easy.


Make 2 short screws from the pan headed screws.


Take a section of 2" PVC and make a slot about 4 inches long through the bottom. This slot allows the assembly to slide on and off of the Body Tube, and allows the catch screw to peek out.


Take your 1-1/4" PVC Tee and wrap a few wraps of packaging tape around the middle arm. Stick it right into the 2" PVC. Push the Tee all the way Referencing the first photo, drill four holes through the 2" PVC through all layers, in an X-shape. Place two shortened screws on opposite sides of the tube, and Put the longer screws in the remaining two holes. The idea is that disassembly may be achieved by backing out the two long screws about 3/8". The "Lower" may then be removed by pulling the PVC Tee off the body tube. Hence the need for the low-profile plunger-stop.


Lower assembly removed. A handle is secured onto the bottom of the 2" PVC, not the body tube. This allows for a modular system. You can swap lowers if you have different asthetics on a different lower, or if a blaster has a catastropic break, make a second "upper" assembly, and just replace that. Save yourself the trouble of making another handle. Just my two cents.


Pumped back. Plunger tube doubles as the pump itself.


Plunger caught back, Plunger tube/pump pushed forward. Ready to fire.


Fully Assembled, just needs a grip.


Results
Every blaster is a learning experience. Some will have you bashing your head against a wall more than others. This was one of those. Troubleshooting probably accounted for 6-7 hours with this thing.

I had to reduce the draw length from my standard 6.25" to about 5.5-5.25". At the same time, the volumetric increase is still crazy compared to the standard 1-1/4" PVC plunger tube. Which is why I was baffled why it was actually shooting with less force than my rainbow pump, I'd wager 150-200 fps on a chrony; my Rainbowpump by comparison rocks 220-250.

The problems that plague larger diameter plunger tubes still apply, Namely:
-Increased friction resulting from a larger circumference plunger tube, Where C=(Pi)(Diameter)
-Increased Mass from non-traditional plunger head construction. The bath plug is super dense. As mentioned, I'll likely be replacing it.

On the bright side, the air seal is fucking perfect.


Verdict
Basically, don't build this this if you don't plan to improve it. Because I'm this deep in the rabbit hole anyway, I'll post some kind of update when I get a proper skirt seal from McMaster.


Notes
The thing likes shorter barrels. It's sweet spot is around an 8-9" length of CPVC.

From rear of stock to front of bushing, this blaster is about 3 inches longer than my rainbowpump. When equipped with it's 9 inch barrel and hopper, compared to my rainbowpumps 12" barrel and hopper, both blasters are exactly the same in length. Go figure.

I could have used an omnidirectional, telescoping plunger rod, a la multiple orgasm, but I've had bad experiences with omni rods before. I don't want to talk about it.

The entire hopper and barrel assembly moves back and forth with the plunger tube every time the blaster is pumped. It's oddly satisfying. Could it rattle off in the middle of a war? Perhaps, but the interface between bushing and PVC is very tight. I'm not too worried about it.

The slightly longer length allows for a great grip on the pump/plunger tube, especially if you like to be supa tacticool with your arm extended all the way to the front of the pump.


Thanks for reading. Questions/ comments/ singing telegrams are always appreciated.

Any advice for those of us looking into an engineering/design career? I.E. is there any organization or activity that would help us get hired in a position like yours?

Serious question. I'm going into my senior year of mechanical engineering school. Would just be cool to hear it from the lion's mouth.

WIP Rainbow pup



Barstool musings.

How is your seal with the lathed plunger head? Is there a lot of friction? I'm surprised you're only getting 70 feet considering you getting 7.25 in. of draw on a [k26].

Me too. The fact that you are even getting 7.25 in of draw means you don't have too much pre-compression... is the plunger slowing down as it finishes it's travel? My rainbows only get 6.25" but I pre-compress them about 3/4". Just my 2 cents.

Gucci levels exceeded well beyond 400%. I had a super good time and I look forward to all the cool footage taken throughout the day.

I had loads of fun too! I have submitted a completed video to the collaboration channel dropbox. As soon as he who mods uploads it I'll link it here.

EDIT: Viddy

I will see you there come hell or high water.

Spiderbite, that'd be awesome.

Hoongfu, I got your catch all pretty for you.

Koree, super pumped for this war.

EDIT: I'm likely bringing several small cameras for filming for the NIC channel, (and a little for my channel of course.) If anybody has any problems with being filmed, don't hesitate to let me know.

Maybe you could put a brace on it for your arm, like you would find on one of those fancy slingshots? Just something to more evenly distribute pressure.

Yeah this was my original intent, actually. May give it a shot after exams this week.

How awkward is it to prime a blaster like that when it has large spring loads?... Have you noticed any discomfort while priming this repeatedly like you would in a war situation?

Kind of awkward and yes.

The spring load is rather high, but a couple factors help mitigate this. The skateboard tape actually really helps in priming; instead of wasting energy/focus on squeezing the slick PETG, the skateboard tape gives you a great grip on the blaster, allowing you to grab the pump and just pull. When shouldered, your shoulder provides a force balance with your priming hand, so as long as you have the thing shouldered, priming isn't that bad. After limited testing, this seems to be the best way to prime the blaster.

My first war with this thing will be Saturday, I hope to use it in the "pistol" round if it's allowed.

Writeup coming when I have the design perfected.

I've been on a homemade-spree these past few weeks, and I needed a pistol for the New Jersey War this weekend. I wanted something small that packed a punch and has the potential to be in-line with the shooter's arm, a blaster that one could sprint around with if playing aggressively or as a runner. That being said, the resulting blaster is more of a light-carbine Rainbow-Pump Bullpup blaster.


The handle is made of cutting board, the spring is a [k26] cut in half. The blaster gets about 2-7/8" of compression, so it's nearly fully compressed when it's primed. The 2" PETG to the left (front) of the blaster is the priming pump, so it is a top-priming design, like a Recon/Retaliator. The little spring under the pump pulls the pump forward when running or firing on-handed, harkening back to the idea of a "runner's gun."


Just like my Rainbow-pumps, this blaster makes use of an upper and a lower. The upper simply slides into the lower and is secured by two screws in the rear "trunnion" and one at the front. The trigger has to be removed to separate the upper and the lower in this prototype, but that is only because of a mis-measurement on my part. Next version will have a trigger that does not need to be removed to "field-strip."

Opening up the lower reveals how the trigger works:


At rest, the spring-loaded trigger is forward, and the cam to the rear of the trigger is free to rotate. When the blaster is primed, the rainbow catch screw pushes down on the cam.


When the linear trigger is depressed, the cam pushes up on the rainbow catch screw, firing the blaster.


Another shot of the upper, and the protruding catch screw.


PETG pump pushes back on the priming bar, minimizing the chance for face injuries. The skateboard tape is actually really helpful in priming the blaster, especially with such a high strength spring inside.


Even with a 7"-8" barrel, the blaster only measures 22"-23".

I will likely be exploring this design more, but I have enough information here to be useful to someone familiar with homemades. Overall this blaster shoulders surprisingly well, and while I don't have ranges yet, this thing "thwacks" pretty damn hard against the cabinet I shoot at.


Porn.

Thanks for reading. Questions, advice, flames appreciated.

Big and Little brother. Writeup is done on the big brother. Will be making an overview of the Rainbow-Bullpup-Pistol-Carbine shortly.

Have you considered making an omnidirectional catch notch to create even wear and avoid having to worry about the plunger rod turning out of place? Ryan's omnidirectional plunger rod from his Rainbowpump rev. 2 and Daniel Beaver's omnidirectional catch notch (he posted it in the original rainbow thread) are both good options that can be built easily with your tooling.

This design doesn't really require an omni-plunger rod. Should the need arise to meet some future design requirement, then I will absolutely make use of one. But such plunger rods for this type of blaster just add an extra unnecessary step.

Nice! Hand-made rainbow pump is not an angle I anticipated, but it's a cool idea.

Couple of notes about the write-up:
The diagram is the last time many of the measurements are brought up, particularly the distance of the catch from the plunger head. Might be worth duplicating the diagram where appropriate or throwing in an extra photo or two.
The purpose of the winged piece is a little unclear, mainly because I think you skipped the steps where you drill the pump sleeve and screw it into the winged piece.

Thanks! I will update the writeup when I get home tonight, the thing's super easy to disassemble. Looking forward to using it next weekend.