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Homemade Blast Button

For almost all your backpressure-triggering needs.

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#1 Ice Nine

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Posted 23 February 2009 - 12:46 AM

I was recently commissioned to do a project by a friend of mine and the work required revisiting an earlier design. Upon reflection, I decided that there had to be a better way to do the trigger mechanism than the first one I made. Hornet blast buttons seemed like a good place to start; they're simple and (apparently) easy to recreate, but their downside is that they're a tad hard to come by and are limited to firing only the tanks that are attached. I'm working on a revision of this design that will allow for firing a la the SMDTG trigger but for the moment a series of these separated by check valves would work for any multi-shot needs.

Here's what you should start with:

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Two 1/2" CPVC endcaps, a small section of 1/2" cpvc (enough for the two endcaps to sit as if connected directly), some super glue, a brass stud (found in the area of Ace where they have the drawers of screws and nuts), a 1/4" to 1/2" rubber stopper (found in the same area), and a small spring that will fit underneath the stud's head. Not pictured but necessary are two lengths of 1/4" OD vinyl tubing, goop, and a drill.

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That's the stud as it's sitting with the spring on it. I used a part of an AT3K trigger spring, which is suitable but for the next iterations I plan on using something a bit stronger, or the same trigger spring doubled-up. The goal is to have something strong enough to help the seal but weak enough to be easily depressed, somewhat like the SMDTG trigger.

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Drill a hole in one of the endcaps wide enough to give the brass stud some wiggle room. Your goal here is to allow the stud to sit properly while giving the air enough room to escape the chamber, which is the point of a backpressure valve.

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Take the rubber stopper and drill a small hole about an eighth of an inch deep on either side. I would recommend the wider side but it's not necessary (in supergluing the stud in place, I put too much glue in and had to cut off part of the washer; I resorted to using the smaller side for this trigger which hasn't changed the mechanics or seal of it in any way). You want to give the brass stud enough room to sit while having a satisfying amount of trigger movement.

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It should sit like that.

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Take your other endcap and drill a hole in the bottom, just wide enough to shove some 1/4" OD vinyl tubing into. Super glue it in place and goop it once the super glue has dried.

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Not pictured here (but seen in the final product): You'll want to put another hole in the side of the endcap, not too far from the bottom, in order to put a piece of tubing in for the output. This will save you a vinyl tee, which is nice.

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Here are the final pieces before assembly. To glue the stopper to the stud, take your super glue and put a VERY SMALL DAB at the very bottom of the hole you drilled. You absolutely do NOT want ANY SUPER GLUE on the top of the stopper; it will stick to the top of the endcap and ruin the seal by solidifying the rubber. This is not at all ideal in any way and you can not let it happen. If it does, cut it off and try with the other side of the stopper.

Use some adhesive (preferably CPVC cement) to stick the two halves of the trigger to the single piece of CPVC you have. The trigger should be able to take as much pressure as you're putting on your tank. Let it sit.

And voila!

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Beautiful. I tested mine with a Titan pump immediately after sticking it together and it unsurprisingly blew apart. I had to reglue it but it does mean that it sealed perfectly. Enjoy.

Edited by Ice Nine, 18 February 2010 - 01:15 PM.

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Unholy Three: DUPLUM SCRTA, DUPLUM PROBLEMA (2009)

But Zeke guns tend to be like proofs by contradiction

Theoretically solid but actually non-constructive

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#2 rork

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Posted 23 February 2009 - 12:52 AM

That's actually simple enough to interest me in trying it. Bravo, sir.
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#3 Ice Nine

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Posted 23 February 2009 - 12:56 AM

That's actually simple enough to interest me in trying it. Bravo, sir.


I'm glad you approve. I hope you'll enjoy iteration number two next; its design is sitting a piece of paper next to me and should in theory supply the same multi-shot action the SMDTG trigger enjoys; at the moment the most difficult part is rigging up a check valve system that isn't "split the pump's tube and put a check valve on each one."
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Unholy Three: DUPLUM SCRTA, DUPLUM PROBLEMA (2009)

But Zeke guns tend to be like proofs by contradiction

Theoretically solid but actually non-constructive

Rnbw Cln


#4 k9turrent

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Posted 23 February 2009 - 08:45 AM

Ok, Since I'm a semi-newb to air gun mechanics, How does a back pressure valve work? a pretty paint picture work.
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QUOTE View Post

That's about it. And thanks Angela who helped me with these pictures.. It looks huge in her hands.


HOLY CRAP!

FU ALL

#5 Split

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Posted 23 February 2009 - 10:17 AM

Search k9. You're not new here. There are several very nice explanations.

I really like this. At one point I was hypothesizing (hey, spell check says it's real) about improving the Lanard Grenade design, and I figured that it would be best with more back pressure chambers and triggers, so that it was more likely to go off and shoot in the direction of someone, as opposed to going off once every third time and shooting nowhere. With this, that project becomes immensely less expensive. Props.

As for recreating the SMDTG trigger, I'm sure you've seen this, but I just want to make sure. It shows that it uses the pin to act both as the valve and as the check valve for the previous .. valves. That wouldn't be terribly hard to do. People make their own check valves all the time.

Best of luck with that - it has been sort of a dream project for air guns - the ability to make a chain trigger as long as you want on one pump..
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Teehee.

#6 Hipponater

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Posted 23 February 2009 - 02:00 PM

Nice! I really like it. Simple, cheap, and still effective. I might go for 3/4 to make a marvelous salvo without the SMDTG trigger. Then i can fire them separately and not have to get the SMDTG trigger... Definitely a nice idea. I can't wait for the second version.


Ok, Since I'm a semi-newb to air gun mechanics, How does a back pressure valve work? a pretty paint picture work.


Posted Image

Basic Idea. Sorry it's crappy, taking a break from my lab report, so i had to rush.

Top one is the outside view.
Opening the valve (pressing the brass stud in this case) reduced the pressure in the small chamber, so then the air pushes the piston back, opening up the barrel, so the air rushes out.

Edited by Hipponater, 23 February 2009 - 02:03 PM.

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#7 Ice Nine

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Posted 23 February 2009 - 02:12 PM

As for recreating the SMDTG trigger, I'm sure you've seen this, but I just want to make sure. It shows that it uses the pin to act both as the valve and as the check valve for the previous .. valves. That wouldn't be terribly hard to do. People make their own check valves all the time.

Best of luck with that - it has been sort of a dream project for air guns - the ability to make a chain trigger as long as you want on one pump..


As of now I have a two-shot design very similar to the actual mechanism of the SMDTG (as illustrated by Seoulman), and I'll be finished with the building tonight. For the moment though I'm keeping the check valves outside the trigger to keep the internal mechanism as simple as possible.

Of course, if you have no dearth of check valves then a very fun and simple mechanism would be to build a whole bunch of the single-shot ones in series with a check valve in between. I'll get an illustration up later but Zorn and I were joking about putting four of these in series in the front handle of the BBB to fire four BS tanks.

Expect a version two writeup later tonight, everyone. Should be fun.
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Unholy Three: DUPLUM SCRTA, DUPLUM PROBLEMA (2009)

But Zeke guns tend to be like proofs by contradiction

Theoretically solid but actually non-constructive

Rnbw Cln


#8 venom213

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Posted 23 February 2009 - 04:35 PM

I'm digging how people are finally working on these back pressure guns. I'm guessing you saw my homemade trigger. It's eerily similar how our triggers are both based out of CPVC and endcaps. They also both reproduce parts of the Hornet specifically. I was actually just thinking about how I could reproduce just the single-fire blast button of a Hornet. I didn't want to use one of my homemade triggers because it would have just have one tank output on it. This is what I've been looking for.

Edited by venom213, 23 February 2009 - 04:51 PM.

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#9 DJ Mashbot

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Posted 23 February 2009 - 08:24 PM

Did you consider/try using a bolt and cap nut and going straight through the rubber stopper? Not that it would really be necessary unless your return spring was a beast, it just seems like it would be a bit more sturdy. Nice valve though, I'm interested to see the next version.
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QUOTE(dizzyduck @ Apr 1 2009, 09:14 PM) View Post

Forget about ranges; range means nothing if your blaster is a giant rattle after three shots.

#10 Ice Nine

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Posted 23 February 2009 - 10:09 PM

Zorn is in the process of posting his three-stage trigger mechanism; my two-stage one wasn't sealed properly so I won't be able to post its workings until I pick up new parts.

It's probably worth mentioning that I compared in size my blast button to one from the Hornet and with the tubing mechanism still intact the two were nearly identical by size.
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Unholy Three: DUPLUM SCRTA, DUPLUM PROBLEMA (2009)

But Zeke guns tend to be like proofs by contradiction

Theoretically solid but actually non-constructive

Rnbw Cln


#11 roboman

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Posted 24 February 2009 - 12:35 AM

Posted Image

Top one is the outside view.
Opening the valve (pressing the brass stud in this case) reduced the pressure in the small chamber, so then the air pushes the piston back, opening up the barrel, so the air rushes out.


I believe you're describing a piston valve, like this. Piston valves are commonly used in spudguns, and are essentially homemade QEV's.

Edited by roboman, 24 February 2009 - 12:35 AM.

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#12 umpshaplapa

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Posted 24 February 2009 - 12:43 AM

[/quote]

Posted Image

Basic Idea. Sorry it's crappy, taking a break from my lab report, so i had to rush.

Top one is the outside view.
Opening the valve (pressing the brass stud in this case) reduced the pressure in the small chamber, so then the air pushes the piston back, opening up the barrel, so the air rushes out.
[/quote]
How does the air go from the smaller tank into the larger outer tank?
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QUOTE(Talio @ Jun 29 2009, 01:50 PM) View Post

i got a black belt in noob banning in 2004.


#13 Hipponater

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Posted 24 February 2009 - 01:29 AM

(image)

Top one is the outside view.
Opening the valve (pressing the brass stud in this case) reduced the pressure in the small chamber, so then the air pushes the piston back, opening up the barrel, so the air rushes out.


I believe you're describing a piston valve, like this. Piston valves are commonly used in spudguns, and are essentially homemade QEV's.


It's what's used in the Big Salvo and the like, which is what K9 asked about. I guess it is a piston valve.

How does the air go from the smaller tank into the larger outer tank?


I tried to draw it, but it's hard to see, the piston part with the rubber head has two holes on the side to let the air pressure equalize on both sides of the piston. Or, if there aren't two holes, its not a perfect tight fit and air can squeak past on the sides to equalize pressure. I can't remember.

http://nerfhaven.com...showtopic=15455 has some good pictures of BS and hornet tanks.

Edited by Hipponater, 24 February 2009 - 01:31 AM.

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#14 Reagent X

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Posted 22 April 2009 - 09:47 AM

Great job! Now I don't have to waste money on a hornet! :lol:
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#15 Ambience 327

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Posted 22 April 2009 - 11:47 AM

Could you maybe waste some of your time reading the Code of Conduct? Particularly the part about not posting in months-old topics...

Not trying to be rude - just trying to help you prolong your stay here. The Admins here are pretty strict, but the strictness maintains a tight forum where we can discuss nerfing and modding without having to wade through pages and pages of "LOLz I tuk the Air Bastricterz ouuta mi Mavrek n itz now lotz more powerfulz".
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#16 Reagent X

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Posted 23 April 2009 - 07:56 PM

sorry i misread the date I saw the 23rd and thought two days ago. Sorry.

and what was up with the lol thing??
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