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plunger-push-prime blaster

Not sure what to call these

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#1 Daniel Beaver

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Posted 23 November 2011 - 11:57 AM

I've been working on this on and off for the last week, and I finally have a working prototype. The key feature is the internal pump-action mechanism, a section of 1" PVC which houses the catch, and to which the handle and trigger attatch to. All of that nests into the outer shell (standard 1-1/4" PVC). I'm not satisfied with the ergonomics of this layout, so I won't be pursuing the concept any further, but I figured it was worth sharing. This is not a full writeup, but anyone with skillz ought to be able to recreate it

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Unprimed.

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Push forward to prime. The plunger head is held steady by the front coupler, and so the catch/spring rest push forward to compress the spring. Once all the way forward, the trigger engages. The draw length is 6.5".

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Since the trigger is catching the plunger rod, you can pull back the entier plunger rod/head assembly. Once back in the orignal position, you are ready to fire.

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Internals overview. You can't use a standard SNAP catch on this. I used a suicide trigger, but this could also be done with a minaturized rainbow catch, or a ring catch. 1" PVC is annoying to work with, since there are no PVC fittings which fit well. I ended up cutting up a piece of 1/2" PVC so that I could widen it enough for 1/2" CPVC to slide easily through it, and then just wrapped it with duct tape. It is held steady in the 1" PVC via a couple of set screws (which do triple duty - they fasten the handle and trigger as well). Let me know if you have any questions.

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The catch is a type of suicide trigger, to which I added a ring of metal for reinforcement. A 1/2" wooden dowel connects the rear catch section to the plunger head. I have mixed feelings about these. It catches well enough, but only if your nail is precisely the correct length. They also push the trigger into the "open" position when they aren't primed. Probably better to use a different type of catch for this sort of application.

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The trigger and handle might be of some interest. I moved the clothespin back into the handle housing, and flipped the orientation of the L bracket. It ends up being about half the length of a regular SNAP trigger and handle (take a look at the comparison shot below this picture). My implementation is a clusterfuck, but the general layout works fine.

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Here it is next to Quixote, which is 32" long. The push-action SNAP is 26" long, and there is some room to be saved in the rear of the blaster.

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Edited by Daniel Beaver, 25 November 2011 - 08:11 PM.

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#2 Langley

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Posted 23 November 2011 - 12:10 PM

Does it feel awkward to prime? Do you brace it against your shoulder and slide the handle forward and back, or do you hold the handle still and pump the whole gun back and forth? What is that ring on the suicide catch?

Edit:Also, are you using the standard 1" to 1/2" reducer bushing for the front coupler? The flanges on yours are always perfectly flush with the outside surface of the PT, and mine never come close.

Double Edit: Here is a more up to date version of the suicide catch.
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#3 Daniel Beaver

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Posted 23 November 2011 - 01:25 PM

A couple of people have asked me whether this is similar to the OHPB. They're actually not similar at all internally, but the end-user experience is quite similar.


Does it feel awkward to prime? Do you brace it against your shoulder and slide the handle forward and back, or do you hold the handle still and pump the whole gun back and forth?

You hold the main body of the blaster still, and push the handle forward. The motion is not really "awkward", but it's more work than a standard pump-action blaster. In a regular blaster, you are pushing against your shoulder. In this blaster, you are pushing forward against your front hand, which is very non-optimal.


What is that ring on the suicide catch?

It's an internal snap ring, somewhere near 9/16" (but not exactly, I forget which size is optimal. I bought a whole bunch.). I shaved down those little nubs, and used JB weld to hold it. I cut a section from a second snap ring to fill the gap.

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Edit:Also, are you using the standard 1" to 1/2" reducer bushing for the front coupler? The flanges on yours are always perfectly flush with the outside surface of the PT, and mine never come close.


Yep, just a standard bushing. Mine are just super cool.


[
Double Edit: Here is a more up to date version of the suicide catch.


Noted.




I just had a brain-wave while posting this. I might be approaching this blaster from an incorrect angle. Time to cut up my prototype...

Edited by Daniel Beaver, 23 November 2011 - 01:26 PM.

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#4 Daniel Beaver

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Posted 23 November 2011 - 02:20 PM

I can't believe I didn't think of this before:

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Instead of extending the 1-1/4" PVC all the way to the end, I just cut it short and use the 1" PVC for the stock. Far less retarded than before: the handle and stock stay still, and you pull back the entire plunger tube. That of course mean's its not push-action anymore, so the title of this thread is stupid. Time for a re-do.

Edited by Daniel Beaver, 23 November 2011 - 02:24 PM.

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#5 andtheherois

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Posted 23 November 2011 - 03:43 PM

Your new system seems stupid easy to build, so long as you get the catch right. I may take a stab at this with a different trigger. Sort of reminds me of This. However it looks like you could easily slide off the priming handle/PT (not that that's necessarily a bad thing). I've gotta say, awesome job on this.
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#6 CuppaSteve

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Posted 23 November 2011 - 04:41 PM

I think it's pretty funny that the day after I post this, you create this write-up. I guess they're technically opposites since the original design you pushed with one hand and mine you pull with one hand. Still, even though you're re-working it, the original design at least looked far better than mine.
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#7 Daniel Beaver

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Posted 23 November 2011 - 04:42 PM

Sort of reminds me of This.

Indeed.
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#8 mysterio

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Posted 23 November 2011 - 08:38 PM

The end product is just a pump-action snap? Also, how awkward is the original priming versus the new priming?
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If two powerful is a problem then just go with one powerful. I guess this style of hopper will work even beyond three powerful..


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#9 Daniel Beaver

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Posted 23 November 2011 - 09:12 PM

The end product is just a pump-action snap? Also, how awkward is the original priming versus the new priming?


You can go either way. The original push-action version was hard to prime, and therefore sucked. But the pump-action layout has piqued my interest for use in a "serious blaster". You can very easily break down the blaster into it's component parts, and it doesn't rely at all on any priming bars. Here's some more pictures:

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#10 Exo

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Posted 23 November 2011 - 09:47 PM

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Especially from this image in particular, I get the feeling that this gun is slam-fire capable. Although It wouldn't really be slamfire, it would operate like a LAMP, just pull the pump backwards really fast, but it would have to be regularly primed first.

Edited by Exo, 23 November 2011 - 09:48 PM.

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#11 Bchamp22795

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Posted 23 November 2011 - 10:06 PM

I love this! What I see is the entire setup can be reversed (From your original push action) to create a bullpup that primes normally! Great job!
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#12 aj1234119

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Posted 24 November 2011 - 07:28 AM

Have you found the new version awkward to prime with a hopper and barrel attached, because the whole barrel assembly moves when you prime it?
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#13 Daniel Beaver

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Posted 24 November 2011 - 09:04 AM

What I see is the entire setup can be reversed (From your original push action) to create a bullpup that primes normally!

Yes, I definitely want to try a SNAP-4 type design using the setup in the op. Since the priming motion would be reversed, you would have a pull-action bullpup.


Have you found the new version awkward to prime with a hopper and barrel attached, because the whole barrel assembly moves when you prime it?

Yes, and that's sort of a problem. The hopper and barrel jiggle around a lot.
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#14 Daniel Beaver

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Posted 25 November 2011 - 08:13 PM

I built another one of these, this time using a bullpup configuration. Regular pump action, small size. The trigger finally broke, so I guess I'll have to find some other method (some type of ring catch ought to work). I screwed up the dimensions a little bit, so it only has 5" of draw, but there's no reason it couldn't be built with 6.5" of draw. The blaster is very short - 22".

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Edited by Daniel Beaver, 25 November 2011 - 08:15 PM.

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#15 atomatron

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Posted 25 November 2011 - 11:23 PM

Huh, the rainfire appears to have sired a child. I KNEW it was up to something.


On another note; are you having any problem with the forward portion being unstable/wobbly? Any ideas to fix this?
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#16 Daniel Beaver

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Posted 26 November 2011 - 09:24 AM

Huh, the rainfire appears to have sired a child. I KNEW it was up to something.

Yep, that was my main inspiration.

On another note; are you having any problem with the forward portion being unstable/wobbly? Any ideas to fix this?

No, not at all - it is very stable. Even when the inner 1" PVC section is pulled all the way out, it is still surrounded by a 2/3rds pipe of 1-1/4" PVC, which holds it snugly. The standard-configuration blasters have an issue with the barrel and hopper being wobbly, since they move in concert with the priming motion. A unibody layout would probably do wonders for that issue.


FYI, I have a video of the bullpup configuration. My catch broke last night, but I figured I would just show people what the priming motion looked like.

Edited by Daniel Beaver, 26 November 2011 - 09:38 AM.

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#17 shardbearer

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Posted 03 December 2011 - 04:09 AM

What's your plunger rod like for the bullpup?
And could I suggest using the Fallopian catch, with either a suicide trigger or a RCB?
And how are the ergonomics on the bullpup?
You should do the wye connection that you used on the Sancho Panza, it would cut ~4 inches off the back.

EDIT: I just thought of combining the snap9 and this. Awesomeness.

Edited by shardbearer, 06 December 2011 - 08:15 PM.

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