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The Two (or Three) Hour Homemade

A Social Commentary on the work of 3DBBQ

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#1 Flaming Hilt

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Posted 13 June 2011 - 08:01 PM

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Video.


NOT A CONTEST ENTRY


- - - Intro - - -


In my time as a nerfer there has always been one quest the NIC can't quite seem to get their hands on. In the words of VACC... well, just see his words here.

It seems to me, however, that 3DBBQ has already conquered this task. His blasters easily meet all the requirements VACC has posted (see "Political Things" #3 and 4 at very bottom of this post). However, I don't think I've ever seen a “3DBBQ style” blaster at a war here in the states. I don't know if it's his awesome paint jobs, the fact that his website is in another language (which Google translate does alright with, I might add), or that he hardly ever posts, but for whatever reason nobody seems to want to reproduce his style of gun.

I'm not here to change that, but I am here with a writeup, and some claims about the ease and the results and general AWESOMENESS. I'll leave further ado at the end since this is supposed to be a writeup and not a political discussion, but first and foremost: ALL CREDIT GOES TO 3DBBQ.

Now, on to business.


- - Key Features - - -


First off, this write-up is long because it's detailed. Don't let that make you think this gun is at ALL hard to build.


This project didn't really have any goals besides “damn, 3DBBQ has got his shit down, let's see if I can't reproduce some of it.” So instead of goals, here are the key features:
- Highly customizable (this write-up is intended as a TEMPLATE).
- Build Time: Less than 2 hours.
- No complicated instructions (in my opinion) or pieces or "cut 1.73mm slot from x to y at height z."
- 100% “homemade” (IE does not use any part of anything made by Hasbro)
- Skill required: Limited. Can you drill straight holes? Okay.
- Cost: $20-30 depending on your pump and chosen accessories. Cost of pipe pieces alone is about $18. My pump was $8 and I needed a $2 barbxMIP.
- Range: At least 60 feet with 2 pumps, but depends on your build, and see range test at the bottom for details.
- Required tools: Drill, hacksaw or pipe cutter, wrench (or handy work with pliers). Maybe a dremel.

I call it (TH)^2. Because I'm a math guy. And “T.H. squared” is kinda catchy to say. Anyways, (TH)^2 breaks down into (T^2)(H^2), which is equivalent to TTHH, which stands for “The Two Hour Homemade.” It could also be “The Three Hour Homemade” depending on how far away your hardware store is. But yea, that's how long it took me, travel time and all. Like I said, 3DBBQ has got his shit down.


- - -Write-up - - -


First I want to make it clear that this is a TEMPLATE. I've included instructions for various available pumps, and you can make yours look however you want. You can easily add or subtract ball valves, air tank space, etc. This is a write-up for the gun you see pictured, but please, modify as you like.

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For the diagram I used 3DBBQ's software which can be downloaded here.

Materials Required:
1/2” Sch. 40 PVC:
18” of pipe
2x Tee
1x Coupler (depending on how you want your handle)
2x Endcap
1x Check Valve
1x Ball Valve (optional)
1x 90 degree Elbow

1” Sch. 40 PVC:
12” of pipe
2x 90 degree Elbow
1x Endcap
1x Check Valve – depending on your pump

Barrel:
I used 1/2” Sch. 80 PVC but you may wish to use something of your own. To follow my plans it will need to fit in a 1/2” Sch. 40 PVC Coupler – perhaps some nested brass?

Other:
1x 1”x1/2” Tee
1x Pump – Mine is a dual-action ball pump from the drugstore for $7.99
1x 1/8” Barb by 1/4” MIP – depending on your pump
4-10x Small screws – size doesn't really matter, about 1/4” long is ideal but no shorter
1/4”x4” Lag Screw – Lowe's #63352
1/4”x1/2” O-Ring – Lowe's #0531, comes in packs of 2

Tools Required:
Drill
Drill bit for your screws (see below)
Drill bit for the lag screw (see below)
Hacksaw or Pipe Cutter
Wrench, or pliers and creativity
Dremel (depending on your pump and how you want it attached)
Hot glue + gun
Super glue
A drop of oil/lube (optional, but recommended. I used Tri-Lube, since I always have some floating around for biking purposes)

Drill bit selection: Rather than letting you mindlessly choose the drill bit I chose, I'll just teach you how to pick the right size. Hold your drill bit in front of your screw like so:

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If you can see the threads poking out the sides but not any body of the screw, your bit is the right size. If you can't see threads, your bit is too big. If you can see the body of the screw, your bit is too small (as is this bit). Voila.

- - -
1. Figure out how to get air from your pump into your gun.

Option 1) If you're lucky, your pump is single action, and fits right into your 1”x1/2” Tee. So for you, this step consists of pushing in your pump and sealing it with hot glue. Yes, hot glue. Did I say hot glue? I've been nerfing for 5 years now and used properly, hot glue is, in my experience, air tight. If you disagree, don't argue (after all, I did say "in my experience"), just use epoxy. Oh, and no BarbxMIP here.

Option 2) If you're less lucky, your pump is dual-action, like mine (see photo below), and/or has a hose. Buy an extra 1/2” endcap. Drill a hole for your MIP in the endcap and screw it in with the wrench, nipple side out. Push the hose onto the nipple. No, you don't need a zip-tie, but it won't hurt. Wrap the endcap in electrical tape until it fits snug in the 1”x1/2” Tee. Glue it in according to the diagram below the photo below. Drill holes in your Tee between the 1/2” endcap and the pump itself (over the nipple of the BarbxMIP) for the backwards action of the pump to breathe. If the pump fits in your tee, glue it in (but it doesn't have to be airtight). If not, see next option.

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Here's a dual-action pump. As you can see, it needs to breathe from both ends, so we can't just glue it in.

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Option 3) Your pump doesn't fit into your Tee. You have two options. You can whip out the dremel and increase the ID of the Tee until it fits (what I did), or you can find another place to attach your pump. If it has a hose this will be easy (drill a hole for the BarbxMIP and follow relevant instructions of option 2). If not... well, I recommend you try another size Tee.

Option 4) You are either extremely unlucky or you got a $0.99 pump. Your pump doesn't have it's own check valve. Unlikely, but possible. If this is the case you need another PVC check valve. I would get a 1” and shove your pump into it, following options 1-3 but replacing the word “Tee” with “Check Valve.” Make sure your valve is oriented correctly.

Note) I recommend, wherever and however you place your pump, that it have a straight line of PVC to the butt of the gun. If not, when pumping, you may find it breaks off, or you may find the force of pumping breaks your gun elsewhere. If the pump makes a straight line of PVC to the butt, the force of pumping goes straight through the PVC and into your shoulder/chest/whatever you pump against.

- - -
2. Cut your PVC (hacksaw/pipe cutter).
You will need 7x 1” long pieces of 1/2” PVC to connect your 1/2” PVC fittings, and I have a 10” tube clip behind my barrel.
You'll need 2x 1” long pieces of 1” PVC to connect your 1” PVC fittings, and I have a 10” piece for my air tank.
Cut your barrel as necessary. Mine is 8” long. I know it could be longer, but I wanted this gun to be compact.

If you want to paint your baby, now is the time, before you have to... you know... take it apart again.

- - -
3. Make your trigger.

Substep 1) If your check valve comes apart, take it apart now.

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Photo is copyright 3DBBQ

Substep 2) Drill a hole in the exact center of the plunger head, for your lag screw. If your valve does not come apart I recommend pushing it all the way back with your drill bit before you begin SLOWLY drilling, and pointing up so the PVC shards come out the bottom and don't get stuck in your valve. FYI, my valve did not come apart, and I did no damage to it (at least, it still works as it should) by following these steps.

Don't worry about going all the way through, we're going to plug the hole with a lag screw anyways.

Posted Image
Photo is copyright 3DBBQ

Substep 3) Gently screw in and out your lag screw. This threads the hole so it will be easier to get in when it really matters.

Substep 4) Drill a hole in the exact center of the closed side of your Tee.

Posted Image
Photo is copyright 3DBBQ

Substep 5) Drill a 1/2” diameter slot centered over the hole you just drilled, from the inside out. DO NOT go all the way through.

Substep 6) Super glue your o-ring into that slot. It's tricky to get the glue into the middle of the tee but it's doable with some patience, and maybe a toothpick. Wait to dry.

Substep 7) Attach the Tee to the back end (IE the end air comes only out of, and never goes into) of the check valve. Screw your lag screw into the tee and then screw it a comfortable distance into the plunger head (it should give only with the valve when you push/pull on it, and if you put your valve together and blow on the opposite end, it should work as a trigger should).

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Photo is copyright 3DBBQ
He uses a hex head for his drill, but a wrench will work just fine.

Substep 8) If you took apart your check valve, put it back together.

Substep 9) (Optional) Add a drop of oil/lube to the outside of the lag screw. Hold the trigger assembly with the lag screw up so the oil drips down to where the O-ring is. If you don't do this your o-ring might keep your valve from automatically resetting. If you don't have lube you can put a spring between the head of the lag screw and the outside of the Tee to solve this.

- - -
4. Anything not together, push together HARD. PVC cement if you wish – I don't think it necessary, but if you feel otherwise, do otherwise. Remember to shave a ramp shape into the back of your barrel so the loading mechanism works properly.

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Between fittings use your 1” long connectors. The rest should be pretty self-explanatory.

I recommend filling the red piece with hot glue. I haven't proven any physical ramifications but it can't hurt. Theoretically, it keeps air from “flushing” into the bottom of the handle, moving it that much faster to the barrel, improving ranges (?). I don't know. But like I said, can't hurt.

- - -
5. Screws

To keep this thing from blowing apart you'll want to put screws anywhere you have a PVC connector. I just have my screws on the 1” connections, actually – the 1/2” stuff hasn't blown apart yet (from the perspective of a physicist, this makes sense, since the inside of the 1/2” pipe has less surface area for air to pressurize/push out on – but still, choose where or where not to place screws at your own risk).

As long as you use the proper size drill bit you need not worry about creating leaks - your screws will plug the holes you make. Be careful, however, not to drill into a critical part of your pump, or you'll have to buy another (not that I'm speaking from experience... cough I swear, the one-way valve is hard to miss!).

- - -
6. Semi-Auto

Just to add-on to your guide, for the semi-auto function to work in his V6 design, you don't open and close the ball valve each time, you just open the ball valve very slightly and leave it in a fixed semi-open position, that acts as a simple air regulator, the larger the valve opening -- the more air flow that re-fills the space in between each shot.

When you fire a shot, the air between the ball valve and check valve will exit, then the air from the main pipe sections will fill in the space through the small opening at the ball valve.

You'll need to pump it up beforehand with enough air volume and pressure to sustain the firing of many shots though. I've found that 30-40 PSI of pressure (my pump has an in-built pressure gauge) along with the right amount of ball valve opening, was enough to fire around 6-7 shots continuously in semi-auto.

Try it out, you'll see how the semi-auto system works. :)


Here's a demonstration by 3DBBQ himself.

I personally have not had any luck with this method, but I suggest you try it, it might be a function of being me.

function doesthiswork(areyouhilt)
|if hilt, then false
|if !hilt, then true}

I'm going to try another system later this week and, if successful, will post instructions here.

- - -
7. Extra

I chose to zip tie my pump to the T of my barrel. This helps keep it stable when pumping. I'll edit this section if anybody else thinks of anything else one might want to do.

- - -
Done. And you thought there would be as many steps as step 3 had substeps.

To reload you can just drop darts in the front of the barrel. The firing sequence is then pump, tilt forward, tilt back/aim, fire, repeat. I've never liked this loading method because I always get either too many or too few (IE zero) darts in the barrel, but with practice, I'm getting better. I recommend you give it a try. If you're not up for it, consider swapping the T for an elbow, and loading one at a time.

You can also use the ball valve for a semi-auto effect, but with two pumps a shot I haven't found this necessary. Pumping takes less time then opening and closing the ball valve for me. As well, one might need a bigger tank for the ball valve to have a decent effect.


- - - Ranges - - -


My clip holds 4 darts + 1 in the barrel so that's how many I tested.
2 pumps (recall this is a dual-action pump):
63 ft
70 ft
71 ft
67 ft
73 ft

For political reasons (welcome to my University) I only use stock darts – at 3 pumps or more they all fishtailed. I'm interested to see the ranges that someone with a similar build gets when using stefans.

Also, recall I am using a Sch. 80 barrel, which is roughly equivalent to 19/32” brass – a tad big. This makes for easy front loading, but you may wish to use a smaller barrel and I'm guessing you'll then get better results.


- - - Further Ado/Political Things - - -


1. As I mentioned, all credit goes to 3DBBQ. Except the actual writing. My fingers are on this keyboard. Why? Simply because I don't give a shit about the flame wars created by claiming credit on this forum. This write-up is solely for the good of the sport. I don't want to waste one post about who came up with what first or “isn't this mine because I put that PVC tee there” – I just want to see this out on the field. It's a good, cheap, easy-and-quick-to-build, effective, highly customizable design. Yes, I know I used a lot of adjectives there.

E.G. if you're thinking of posting: “So basically you did a writeup of 3DBBQ's work,” the answer is “Yes.” And he gets all the credit.

2. Why do a write-up of somebody else's work: After building a 3DBBQ-style gun I can claim they are ridiculously easy to build and yield phenomenal results. 3DBBQ has done plenty of work already with the guns themselves and his website, not to mention the write-ups would be hell to translate (nothing personal... I wouldn't want to do a write-up in a forum of his language either). It seemed like common sense to me to publicize something that worked so well and should be (in my opinion) in much wider use. If 3DBBQ or the mods have a problem with this, I understand – just lock the thread. Apologies in advance.

3. This is not my work and thus obviously not an entry in the mod contest. I pointed out VACC's requirements because in my opinion, they are exactly what the NIC has been looking for in an airgun and exactly what this design meets.

3.5/4. In order to meet VACC's requirement #2 (easily regulatable) you need an appropriate size air tank, an appropriate strength pump, or McMaster-Carr #48435K71 (thanks T3K for the part number).

5. I admit I have thought about VACC's reward and no, I don't think I deserve it under any circumstances (for starters, this isn't a submission to the contest). I just bring it up because I think it would be cool to offer it to 3DBBQ.


- - - Personal Statement - - -


For a long time I have looked for the cheap way out. Cheap pumps, cheap parts, not even willing to build a gun if it costs more than $15. Well frankly, that sucked. Most of my guns held up a few matches but in the end, it seems like (provided you are spending reasonably) the more you spend the more you get. Or, “you get what you pay for.” When I first started on this adventure I made a deal with myself to spend as much as necessary. I ended up spending $30, which all in all wasn't bad. And she works. Beautifully. So if you're sitting there thinking, “I can get by with crayola barrels,” then go back to third grade.

For example, I think that dolling out $6 for the check valve was definitely worth a trigger that worked. I know there are homemade air gun triggers out there, but this one was easy to make, and I don't see much that could go wrong. I mean, the whole point of a check valve is basically to be an inoperable trigger... we just make it operable.

...because these components are more or less designed for this very purpose, once bought they will function flawlessly, and will stand up to much more abuse than most other alternatives (including stock components).


Edited by Flaming Hilt, 19 August 2011 - 08:23 PM.

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#2 dajstafarian

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Posted 13 June 2011 - 08:12 PM

Nice design, it's simple enough, yet quite effective. Two pumps give you a decent range and it's inexpensive and not time costly. I could see this having a great standing with the rest of the NIC. Nice work!
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#3 Carbon

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Posted 13 June 2011 - 10:40 PM

Hilt! Good to see you back.

Major props for the in-depth writeup, this is a real service to the NIC. 3DBBQ is the original Mad Scientist of NH, but his work never got the adoption that it should have. Part of the problem is language, part of it is doing the legwork to adapt his design to the parts available here, part of it is that a lot of his old threads have a lot of broken image links. No matter the reason, hopefully this thread will make these beauties pop up a little more often around here.
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#4 SgNerf

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Posted 14 June 2011 - 12:59 AM

Flaming Hilt,

Nice guide you've written for the english-reading population of the NIC.

I'm also a fan of 3DBBQ's designs and have replicated a few of them over the past few years too, like in this example of my version:

Posted Image

Just to add-on to your guide, for the semi-auto function to work in his V6 design, you don't open and close the ball valve each time, you just open the ball valve very slightly and leave it in a fixed semi-open position, that acts as a simple air flow control valve, the smaller the opening -- the slower the air flow re-fills the space in between each shot to equalize the air pressure.

When you fire a shot, the air between the ball valve and check valve will exit, then the air from the main pipe sections will fill in the space through the small opening at the ball valve.

You'll need to pump it up beforehand with enough air volume and pressure to sustain the firing of many shots though. I've found that 30-40 PSI of pressure (my pump has an in-built pressure gauge) along with the right amount of ball valve opening, was enough to fire around 6-7 shots continuously in semi-auto.

Try it out, you'll see how the semi-auto system works. :)

Edited by SgNerf, 21 July 2011 - 01:23 PM.

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#5 T3K

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Posted 14 June 2011 - 02:07 AM

Nice. REally size doesn't matter, and a regulator wouldn't be the best path. Get a OPRV from mcmaster 25-35 psi are fine. I've NEVER had complaints with them even by a man who protests a lot of blasters.
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#6 Ozymandias

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Posted 14 June 2011 - 02:19 AM

Very nice.

Can we get a firing vid?

Also, where did you buy that check valve? I have never seen that sort of thing at Lowe's/Home Depot.
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#7 Boot

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Posted 14 June 2011 - 09:02 AM

It's great to see that other people recognize the contributions of 3DBBQ. Seeing his simple pneumatic designs was what really brought me into nerf, and what convinced me I could actually build the concepts I had in my head.

I think in this case though 3DBBQ's real genius is the concept of the manual operation of the check valve. As you said, other homemade valve designs exist, however getting them to work properly requires materials and a level of craftsmanship (and patience) that is not available to many people. These check valve's are cheap off the shelf parts that are more commonly available than more expensive QEV's and sprinkler valves.

Also, you are very right on the adaptability and customizability of this system. I just recently rediscovered 3DBBQ's work and have been doing my own experiments. I started from the simplest systems and have been working my way up to more complex pneumatic systems using the concept of manually disengaging a check valve (and hope to eventually post a writeup similar to your's). One of the most effective systems I have had is the most basic. By simply attaching a pump to a manually activated check valve and a length of PPR you get a reliable, indestructible air tank that, through the varying of PPR length can operate like anything from a 2k tank to a drain blaster.

Although I know this doesn't apply to many, if you live in Asia this seller on 淘宝 sells great PPR check valves (in metric units...sorry) for just 2.6RMB a piece (for ones with 20mm connections), the equivalent of about 40 cents each. I bought 100 of them about two weeks ago when exams ended and have been having a blast ever since.

Another great thing is that because these components are more or less designed for this very purpose, once bought they will function flawlessly, and will stand up to much more abuse than most other alternatives (including stock components). In the case of PPR check valves in particular the components are rated to a WORKING pressure of a enormous 250PSI, and a failing pressure of something ridiculous like 1000PSI (assuming they are joined correctly through melting the parts together).

I am really very grateful that you took the time to write this up. Even though you did not discover this general system you have fully opened it up to the NIC, and that in itself is worth praise. I look forwards to what you, and the rest of the NIC add to this design, and will be sure to play my part in the development of cheap, readily available air pressure blasters :lol:

Edited by Boot, 14 June 2011 - 09:09 AM.

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#8 Flaming Hilt

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Posted 14 June 2011 - 12:05 PM

dajstafarian/Carbon -- Thanks, it's good to be back (who knows for how long -- I start another job on Monday), and good to know this is well received.

SGN -- I have actually tried the "mostly closed" method on the ball valve for getting semi-auto to work, and can't quite get it. It seems like the valve is either too far open, or just plain closed. I'm guessing I need a bigger air tank or a more precise valve (3D uses brass, I think, and his handles are longer). I'll keep trying when I've got time to kill, but other thoughts/advice would be appreciated in the meantime.

T3K -- A good thought, I'll add it to the write-up if you don't mind.
EDIT: Can't seem to find the part you're talking about (unless it's one of these $60 guys...) could you please point me in the right direction?

Ozymandias -- I'll try and get a video up later today. I got the valve at Lowe's in the section with the ball valves (bottom shelf), in the same aisle as the rest of the fittings. Smaller hardware stores generally don't have them, I think because they are primarily a "contractor item." But I have seen them at Homie D's and larger Ace Hardware stores. McMaster has them as 46835K52, though beware of shipping costs.

Boot -- It's interesting to note that other people seem to be as interested as I, yet we hadn't discovered each other until just now. Maybe we should have developed a cult instead of posting a write-up. :lol: And you said it best,

...because these components are more or less designed for this very purpose, once bought they will function flawlessly, and will stand up to much more abuse than most other alternatives.

Thanks for the input/commitment to cheap parts. :)

Edited by Flaming Hilt, 14 June 2011 - 12:06 PM.

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#9 SgNerf

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Posted 14 June 2011 - 01:40 PM

SGN -- I have actually tried the "mostly closed" method on the ball valve for getting semi-auto to work, and can't quite get it. It seems like the valve is either too far open, or just plain closed. I'm guessing I need a bigger air tank or a more precise valve (3D uses brass, I think, and his handles are longer). I'll keep trying when I've got time to kill, but other thoughts/advice would be appreciated in the meantime.

Hmmm... i use a PVC ball valve too and it works in my unit.

I guess you'll just need to keep adjusting and testing it until you get the right amount of valve opening to get the semi-auto function, the opening needs to be quite small to get the effect.

From the looks of the air volume in your existing PVC pipe setup, it should at least be able to sustain a few shots at one go, though a larger air tank does allow the option for more shots. :)

Edited by SgNerf, 14 June 2011 - 01:45 PM.

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#10 Ozymandias

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Posted 14 June 2011 - 02:24 PM

Ozymandias -- I'll try and get a video up later today. I got the valve at Lowe's in the section with the ball valves (bottom shelf), in the same aisle as the rest of the fittings. Smaller hardware stores generally don't have them, I think because they are primarily a "contractor item." But I have seen them at Homie D's and larger Ace Hardware stores. McMaster has them as 46835K52, though beware of shipping costs.


Ah, thanks fir the info.

I guess you'll just need to keep adjusting and testing it until you get the right amount of valve opening to get the semi-auto function, the opening needs to be quite small to get the effect.


A suggestion: take the piece of SCH 40 PVC between the check valve and the ball valve, stick some 1/4in. tubing in there, and goop the space around it. That should do the trick, I think.

You might want to use a longer piece of pipe though, otherwise the smaller diameter would mean less volume per shot.
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#11 Flaming Hilt

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Posted 14 June 2011 - 03:14 PM

I think what I'm going to do is mount some tubing as a bypass around the ball valve. That way when the valve is (all the way) closed, the tubing (hopefully) restricts the air enough to create a semi-auto effect; otherwise, I can open the valve for single shots. Or even better, I'll just drill a hole through the ball with my smallest bit. Same effect, less $/exposed tubing... if only the small diameter bits were the long ones.

In the mean time I'll keep fiddling, but it seems like in the field an "Off-On" semi-auto is better than a "Maybe... almost there... oops, too far" semi-auto. Not that experienced valve operators like SGN can't achieve the "Off-On" effect without further modification. ;)

Edit: Video is up.

Edited by Flaming Hilt, 14 June 2011 - 03:22 PM.

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#12 aj1234119

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Posted 14 June 2011 - 09:15 PM

The semi automatic idea might work better if you had a larger chamber between the ball valve and the check valve, as (At least I think after reading SG Nerf's post) that is the air used for firing the dart if you use it as a semi automatic blaster. If I can find a check valve, I'll build one of these (slightly differently) soon.

Also, couldn't the time you hold the trigger down for have an effect on whether the blaster could shoot semi automatic or not (longer trigger pull lets too much air escape and there is none left to fire the next dart)?

Edited by aj1234119, 14 June 2011 - 09:33 PM.

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#13 SgNerf

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Posted 15 June 2011 - 03:46 AM

In the mean time I'll keep fiddling, but it seems like in the field an "Off-On" semi-auto is better than a "Maybe... almost there... oops, too far" semi-auto. Not that experienced valve operators like SGN can't achieve the "Off-On" effect without further modification. ;)

For my unit, i simply adjust the ball valve opening until i get it to fire in semi-auto, then i leave the ball valve in the same position for the duration of the entire Nerf game (or until i want to increase or decrease the air flow to adjust the shot power). The blaster can be pumped up multiple times after that without re-adjusting the ball valve. I guess its pretty much like adjusting the air regulator on an air tank device.


The semi automatic idea might work better if you had a larger chamber between the ball valve and the check valve, as (At least I think after reading SG Nerf's post) that is the air used for firing the dart if you use it as a semi automatic blaster. If I can find a check valve, I'll build one of these (slightly differently) soon.

Also, couldn't the time you hold the trigger down for have an effect on whether the blaster could shoot semi automatic or not (longer trigger pull lets too much air escape and there is none left to fire the next dart)?

You've a good point there, having a larger chamber between the check valve and ball valve would allow more air volume to fill the space and consequently more power to propel the foam dart, though the offset is that'll also consume more air volume from the main air tank pipes, which would reduce the number of shots. Anyways, the final power and number of shots can still be tweaked by changing the size of the ball valve opening, so everything is still adjustable.

Yes, to use the semi-auto function, the trigger pull has to be fast or else excess air will keep escaping. If you watch 3DBBQ's firing video, his trigger pulls are done in a quick snap-like motion. Thats how the blaster is fired in semi-auto.

Edited by SgNerf, 15 June 2011 - 05:11 AM.

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#14 Flaming Hilt

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Posted 15 June 2011 - 04:02 PM

The semi automatic idea might work better if you had a larger chamber between the ball valve and the check valve, as (At least I think after reading SG Nerf's post) that is the air used for firing the dart if you use it as a semi automatic blaster.


This is wise. I will try adding a small chamber (perhaps just a T with an endcap on the outlet) and post the results.

I acknowledge SGN's reservation that this will take air from the main chamber, but right now I think I'm getting a semi-auto effect, just a weak one. IE, pulling the trigger makes the same magnitude of "pop" each time (and thus I assess, the same pressure of air is being released, which is what we want), but this "pop" is hardly strong enough to get a dart out of the barrel.

EDIT: After watching 3DBBQ's semi-auto demonstration (which I have posted in the semi-auto section of the write-up) I note that his active air tank (the part between the ball valve and the check valve) is about as big as mine. I would conclude that he just pressurizes his tank more than I do, but (by my guess) we're using equal size pumps and pump relatively the same amount of times. Perhaps I just have bad luck with air guns.

For my unit, i simply adjust the ball valve opening until i get it to fire in semi-auto, then i leave the ball valve in the same position for the duration of the entire Nerf game (or until i want to increase or decrease the air flow to adjust the shot power). The blaster can be pumped up multiple times after that without re-adjusting the ball valve. I guess its pretty much like adjusting the air regulator on an air tank device.


I understand where you're coming from and think it a valid point, but I would like to be able to switch on and off the semi-auto mid game. Of course, with practice I'm sure I can find that perfect spot in just a second or two.

Edited by Flaming Hilt, 15 June 2011 - 04:04 PM.

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#15 aj1234119

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Posted 15 June 2011 - 04:53 PM

It may just be me, but it looks like 3DBBQ uses PVC with a bigger diameter for the space between the ball valve and the check valve (his tank is the same sive PVC as the space between the 2 valves), and that would give it an increased air volume.
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#16 arfink

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Posted 16 June 2011 - 10:10 PM

I just built one of these today. It took considerably longer than 3 hours, but only because I opted to glue everything down instead of using screws. The design works brilliantly, though I chose to forgo the semi-auto route and require pumping between shots. With an integrated RSCB it makes a little more sense to do it that way anyhow, since I tend to point the blaster slightly down while pumping anyway.

Besides omitting the ball valve I chose to use 1/2 PVC for the whole thing, including the tank. (but not the barrel, of course) Since I wasn't going for a really high tank volume for semi-auto fire I felt I didn't need to use bigger pipes. I am getting 100+ foot ranges with a 5 shot clip and 2 feet of barrel, firing 1BB stefans w/dome heads, but I'm thinking of cutting it down to a little over 1 foot because it's just too long to handle easily. If I did this design again (and I probably will) I'd likely go for a different frame style or try and do the semi-auto thing. I'll try to take pics of mine later, but it basically looks like a skinnier version of the same thing, and without a ball valve. Parts cost was under $25 for the whole thing, every part of which I found at Ace Hardware.

One more thing- 3DBBQ seems to also like the single-shot setup as opposed to semi-auto. Check out his newest blaster:

Posted Image

EDIT: one other thing to note: I got the style of check valve that has metal internal components. No big deal, just instead of drilling into the valve head I chose to leave the triggering pin floating and added a nut on the backside to keep it from falling out. Seems to work fine, though it might be a nuisance in a war. I'll have to use it more and see. Oh, and since I wasn't using the bigger pipes I used a 1/2 PVC to 3/4 PVC adapter pushed through some 1.5" PVC which I then generously sanded (for an hour, by hand. I know, I need to invest in a dremel) to wedge the pump in there. When I take the pics you'll see what I mean.

Edited by arfink, 16 June 2011 - 10:31 PM.

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#17 shardbearer

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Posted 17 June 2011 - 05:40 AM

These are nice, but I do see a couple of flaws. Most of it is performance related, such as the bad flow and huge amounts of deadspace. With a bit of work, I designed one that greatly reduces the deadspace, and gets rid of that horrible button trigger.

A bit of poking around on the Taiwanese forums reveals that you guys are building off old technology. The gun all your designs are based off of was made in november of 09, not exactly current, and since then he has made four more semi auto revisions, the SCAR, X2, D3, and ELITE. The big improvements are the needle valve, which replaces the ball valve in a much more compact and easy to make way, as well as the air assisted RSCB. The pipe in the handle is left open, connected to the clip at the back of the RSCB, pushing the darts forwards and eliminating the need to shake it down.

Needle valve:

Posted Image

Black is a reducing tee, whatever size your tank is on the sides and 1/2" on top. Red is PVC going to the valve, drilled or sanded out where the CPVC has to go in. The CPVC is the blue, with an endcap in green with a 1/16" hole in it. Simple as that. The same thing can be done inline with a reducing coupling instead of the tee, as shown in the ELITE.

I think you guys will like my design. You should see it either by sunday or when I get back in August.
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#18 arfink

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Posted 17 June 2011 - 10:38 AM

These are nice, but I do see a couple of flaws. Most of it is performance related, such as the bad flow and huge amounts of deadspace. With a bit of work, I designed one that greatly reduces the deadspace, and gets rid of that horrible button trigger.

A bit of poking around on the Taiwanese forums reveals that you guys are building off old technology. The gun all your designs are based off of was made in november of 09, not exactly current, and since then he has made four more semi auto revisions, the SCAR, X2, D3, and ELITE. The big improvements are the needle valve, which replaces the ball valve in a much more compact and easy to make way, as well as the air assisted RSCB. The pipe in the handle is left open, connected to the clip at the back of the RSCB, pushing the darts forwards and eliminating the need to shake it down.

Needle valve:

Posted Image

Black is a reducing tee, whatever size your tank is on the sides and 1/2" on top. Red is PVC going to the valve, drilled or sanded out where the CPVC has to go in. The CPVC is the blue, with an endcap in green with a 1/16" hole in it. Simple as that. The same thing can be done inline with a reducing coupling instead of the tee, as shown in the ELITE.

I think you guys will like my design. You should see it either by sunday or when I get back in August.


Yeah, saw the pin valve earlier today as I was poking around, looks to be alot easier to work with. I just didn't care about having semi-auto fire in my first all-homemade air blaster. There are alot of other kinks I need to work out before I build another one, like finding a good pipe/pump match. The "Spalding" ball pumps kinda suck for fitting into anything. If I build another one I'll likely use one of those bike air hoses like in some of his newer designs.

Lastly, I'm curious how you're thinking of solving the deadspace issue. An RSCB is going to basically *force* you to have a certain amount of deadspace, no matter how you do it, unless you're constricting the air pathway, which is probably more troublesome than the deadspace is. That's why people developed inline clips and hoppers. Now in my case, since I'm basically firing the whole tank every time I shoot the blaster, the deadspace makes little to no difference at all. The thing has way more than enough air volume to compensate. I imagine that in a semi-auto configuration it'd be simple to increase the size of the firing tank to compensate.
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#19 shardbearer

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Posted 17 June 2011 - 06:01 PM

For the deadspace, I plan on minimizing the amount of pipe between the rscb and the check valve. That little orange gun is a prime example of this deadspace.

I also like the idea of having a ball valve that you can flip to adjust the amount of power. My idea for this is to put a straw through the hole in the ball valve, and fill the area around it with hot glue. This would be the high power, and you would get like 2-3 shots per tank, and then you could turn it to what would normally be closed, where there is a 1/16" hole through it, and with this you would get more like 6-7 shots. This way you do not have to do any finicky adjusting in the middle of the war, just high or low powered.

I checked both Aubuchon and Home Depot, and neither had check valves. Anyone had luck at Lowes?

And while I am looking, I want to be working on it, so can anyone tell me how far the trigger pull is? It looks from his video like 1/4". And how much distance is between the back of the pipe right in front of it and the front of the piston (in it's forward position). From his pictures about 1/8"?

I encourage you all to check out both 3DBBQs website and the Taiwanese forums. Almost every gun over there is one of these. And Google Chrome automatically detects that they are in Chinese and translates the whole page into english. I cant imagine trying to read them without Chrome.

The unfortunate thing is that if we have a question we cant ask.

Edited by shardbearer, 18 June 2011 - 02:46 AM.

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#20 arfink

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Posted 18 June 2011 - 11:26 AM

Well, for mine the trigger pull is maybe 1/4 inch tops. Maybe. But it's totally dependent upon your check valve, so I'm not sure. If you want more pull you can always have a floating trigger pin like in mine but with an extra spring. I don't see much point in doing that though.

I'm planning on going out for parts for a second revision already. I'm ditching the RSCB altogether and going with an inline clip, but that'll make more sense once you see how I'm setting up the check valve- vertical instead of horizontal. With a triggering bar that goes over the top and down the side of the valve body, rather like those spray-paint trigger adapters. Then I'm adding more of a paintball-like setup for the main tank, with the foregrip serving as the the smaller "firing volume."

The pin-hole ball valve idea is a cool one. I'll have to try that out. :)

And yeah, they have some really cool stuff on their forums, but the google translations are pretty terrible most of the time, making it hard to understand what design features these guns have, aside from looking at the pictures.
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#21 SgNerf

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Posted 18 June 2011 - 10:39 PM

Just to add, hopper clips can be used in these designs too, it effectively solves the automatic dart advancing issue with RSCB clips. :)

I''ve been running my V6 units with hopper clips for the past few months and they work nicely, eliminates the need to keep pointing downwards or using external tube systems to route air for advancing the shots.

I guess the reason why 3DBBQ and his group haven't got around to using hopper clips is most probably because they have difficulty getting suitable PVC wyes in Taiwan... i can't get them in Singapore too (the local PVC pipe brands don't make wyes in the right dimensions), so i had to specially order and ship them in from the States.

Edited by SgNerf, 19 June 2011 - 11:40 PM.

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#22 b1g13en

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Posted 19 June 2011 - 12:31 AM

For the trigger setup is the screw supposed to be screwed into the check valve? What length screw are you guys using for the triggers ( if it helps I am planning to use the pvcT setup) or it doesn't really matter? Also any tips on hole to drill into the center of the tee?

Edited by b1g13en, 19 June 2011 - 12:39 AM.

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#23 shardbearer

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Posted 19 June 2011 - 09:08 AM

Preliminary dry fitting. Unfortunately I leave for france in an hour so I wont be able to finish this till I get back in a month. Entirely constructed out of 1 1/4" PVC except the handle, the check valve fits perfectly inside it and is airtight with a bit of hot glue. For a needle valve I am using a 3/4" cap with a hole drilled in it, and you can move it around to adjust number of shots and power. Sorry about the horrible image quality, I had to use my webcam cause im in a rush.



Posted Image

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#24 arfink

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Posted 19 June 2011 - 02:24 PM

For the trigger setup is the screw supposed to be screwed into the check valve? What length screw are you guys using for the triggers ( if it helps I am planning to use the pvcT setup) or it doesn't really matter? Also any tips on hole to drill into the center of the tee?


If you have a check valve that has all plastic parts inside you can screw right into the head of the check valve. American made check valves tend to have a metal rod running through them. I'm using an American style check valve, so in my case I am using a 1/4" diameter (I think) hex bolt instead of a lag screw. What I did was I noticed that the check valve's post stuck just slightly over the top edge, so I found a screw that was only slightly longer than the T-fitting so it would poke the check valve head. Also, with the floating-bolt setup it's important to remember that your hole for the bolt needs to be dead on center and perfectly straight if you can do it. If not, make the hole slightly larger and attach a couple of nuts to the very end of the bolt (once you have it in the hole) so that the tip of the bolt can't slip past the pin in the check valve. I'll have to take pictures of this or it'll not make sense.

For the length, it's all up to you how long you want it. You can of course experiment before making anything permanent by just slipping different bolts in there and seeing what you like.

@shardbearer- I like how you and I came up with almost the exact same overall shape, but mine has stuff put in different places. :) Will take pics of my new one pretty soon. Mine's currently hitting 100ft with mini marshmallows (when they don't swerve like a sumbitch) and it pushes stefans so hard that none of them will keep tips on, so I have no idea how far the tips are going, I never found any of them ourside. This is of course just holding the trigger down and dumping the whole tank at once. Semi-auto firing also seems to be working, but my inline clip is not big enough to know how it's performing. A 12-shot inline clip with 1 foot of barrel is dumping all 12 darts on the first "shot" of the tank, shooting them an average of 70 feet with a 4 foot spread. So yeah, need a hopper. :)

Edited by arfink, 19 June 2011 - 02:25 PM.

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#25 Flaming Hilt

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Posted 20 June 2011 - 12:19 AM

For the trigger setup is the screw supposed to be screwed into the check valve? What length screw are you guys using for the triggers ( if it helps I am planning to use the pvcT setup) or it doesn't really matter? Also any tips on hole to drill into the center of the tee?


arfink already covered this a wee bit but I wanted to add notes for my specific design.

As specified in the write-up, I'm using a 1/4x4 lag screw. This means it's 1/4" in diameter and 4" long. For 1/2" PVC with the tee directly connected to the check valve I find this to be the perfect length. I like lag screws because they have pointed ends, so they are easier to get started in a non-pre-threaded hole than a hex screw.

The screw is screwed into the valve part of the check valve -- that is, the piece that moves. If you stare down the front of your valve (the end that air only comes out of) you should see a small cylinder of PVC on the inside -- that's what you want the screw attached to.

My tip for drilling the hole is this: slow and straight.
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