19 replies to this topic

[BOSS9]

First, we need some background. This is a scaled-down prototype. It requires 3 nesting tube sizes, and I chose to build this on a small scale using materials I had on hand before building a final version. This thing is not built for performance. It shoots ~60-70s, but I've never actually tested and never will, it doesn't matter. This is just a demo of a possible internal pump-action system that I’m hoping others can build on. It’s not very efficient in terms of plunger volume considering its overall size, but it’s the system I want for the final version.

This is post-mod (by almost a month), so it’s not a full write-up, and I’m assuming no one will replicate it exactly anyway in it’s scaled-down version. I do, however, hope others will use this concept in some way or another.


The “finished” product:



Closeup on the ridiculously comfortable handle (based off a recon- but better):



Closeup of the priming handle. I dislike vertical handles, but this was easier than a nice wood one.



Sweet RSCB spacer, ‘cuz it’s nice.



This uses a rainbow catch, with the catch notch at the end of the plunger rod- similar to Slug’s 2-11.



An exploded view of the internals. The 1” PETG at the top is the plunger tube, with the spring rest built in to the end. The plunger tube is fixed in the “shell,” or 1 ¼” PVC.The plunger rod is made of ½” OD ⅜” ID PEX with ⅜” OD ¼” ID PEX nested inside to form the 360 degree catch notch. The priming slide on the bottom is 1” PVC and floats over the plunger tube and slides along the ½” plunger rod, pushing back on the section of ½” CPVC to prime it.



To disassemble there are 3 set screws holding the front of the plunger tube in place.



The entire internals can then slide out, leaving just the catch in the shell.



The internal assembly.



The priming slide and plunger pulled back. When in the shell the catch would be engaged.



Unscrewing these two screws releases the spring rest from the plunger tube, and the plunger tube can be removed.







With the plunger head removed.



The priming slide.



Closeup of the plunger tube. Note the awful materials and implementation of all of these parts. That will go away in the full-size version.



Plunger head. Clusterfuck of various washers. Seals wonderfully, but has to be re-tightened.



Catch/end of the plunger rod. That’s an “I fucked up measuring” snap-on CPVC spacer. Note the screws and beveling.



Another closeup of the priming elements extended.



The catch when primed (picture taken of the gun assembled).



Trigger. Has been known to seduce fingers.



Just like the recon. But better.



And a nice closing picture. Can’t get enough o’ dat handle! HGNMMM.



Questions? Hope I explained everything well.

If anyone can help me out with tubing sizes for the final version, that'd be great. The plunger tube (inner of the 3 closely nesting tubes) has to be at least an 1/8" thick, hopefully more- should be able to sturdily take screws. The middle tube has to be pretty thick/durable. More so than the PT. The shell can be relatively thin. Ideally I'd use 2" PVC for the shell. I want the PT to be ~1 1/2" ID. Preferably the tolerances between these would be pretty tight, for a smooth prime.

[KoRnEd]

That looks super sexy. For the larger scale pt, I would recommend 1.25" PVC, with an inner sleeve of 1.5" thin wall.. The shell would probably be 2" PVC. This all fits together like a glove.

[andtheherois]

what size are you using for the PT? I'm guessing 1 inch clear pvc? Your best bet for doing sizes would be 1-1/4" plunger tube, 1-1/2" thinwall slide, and 2" body.

Edit; missed korned's reply, but yeah you wont be able to have a 1.5" PT if you want a 2" body.

Edited by andtheherois, 02 January 2012 - 11:29 PM.

[gehaga]

I don't think I can express how much I love this design. I must go build one this weekend, larger scale of course.

[BOSS9]

'KoRnEd', on 03 Jan 2012 - 04:24 AM, said:

That looks super sexy. For the larger scale pt, I would recommend 1.25" PVC, with an inner sleeve of 1.5" thin wall.. The shell would probably be 2" PVC. This all fits together like a glove.

The reason the popular 1 1/4" 1 1/2" thinwall 2" combo won't work for this is that the thinwall section would be too flimsy. Thinwall just can't hold screws in the way I need it too- I want this to be the most ridiculously over-engineered primary ever. Also, I'm looking for over 110' ranges with a hopper (which is what my current primary gets) which would mean 7" draw with a 1 3/8" ID PT. With this design the gun would be way too long with a barrel and stock using 7" draw, so I need a larger PT with higher spring power to get similar ranges with far less draw. Thinwall 1 1/4" PVC has an ID slightly larger than 1 1/2" and is exactly what I want to use, but I only have a little chunk of it and need to find more. Ideally I want the middle tube to be ~1.7" ID ~2.0" OD to use thinwall 1 1/4" and 2" for the PT and shell respectively. I'll look on McMaster. The thing is, price doesn't matter for this, as it's designed to be the primary to end all primaries.

'andtheherois', on 03 Jan 2012 - 04:29 AM, said:

what size are you using for the PT? I'm guessing 1 inch clear pvc?

1" PETG is the plunger tube. Slides nicely in SCH40 1" PVC (the priming slide)

'andtheherois', on 03 Jan 2012 - 04:29 AM, said:

you wont be able to have a 1.5" PT if you want a 2" body.

My options for tubing are not limited to PVC plumbing pipes, I can use whatever non-nominal sizes I can find.

'gehaga', on 03 Jan 2012 - 04:38 AM, said:

I don't think I can express how much I love this design. I must go build one this weekend, larger scale of course.

Awesome. I eagerly await news of your experience.


I didn't mention this in the writeup, but Zorn's Fallopian MK2 is functionally identical to this design, but sooo much more efficient with air volume relative to overall size. There's no real reason anyone else should build this over his.

Yet another addition, just to be a fuckhead.

Edited by BOSS9, 03 January 2012 - 12:10 AM.

[Curly]

So the body is like a full-length pump sheath? Safe and sexy, why not?

Longer draws would be a pain, but larger PTs would be fine. 1.5"PT and a 2" pump section fit very nicely, and can be covered with 2.5" PVC (or perhaps ABS pipe to lighten the blaster). The 2.5" has an ID just below 2.5", so with some E-tape the 2.38"OD of the 2" pipe would fit nicely. I can find 2.5" PVC/ABS at a well-equipped hardware store in Canada, so Ace will probably have an aisle dedicated to it.

If you're getting 60'-70' from that huge a clip I'm impressed, perhaps you should consider a Homemade Wye on a BRISC? I haven't tried using hoppers on low output blasters, but it would seem that RSCBs are more suited to that.

EDIT:Forgot to mention, the handle is very sexy. Did you make a template of the handle then dremel off the edges?

Edited by Curly, 03 January 2012 - 12:29 AM.

[BOSS9]

'Curly', on 03 Jan 2012 - 05:26 AM, said:

1. I can find 2.5" PVC/ABS at a well-equipped hardware store in Canada, so Ace will probably have an aisle dedicated to it.

2. If you're getting 60'-70' from that huge a clip I'm impressed, perhaps you should consider a Homemade Wye on a BRISC? I haven't tried using hoppers on low output blasters, but it would seem that RSCBs are more suited to that.

3. EDIT:Forgot to mention, the handle is very sexy. Did you make a template of the handle then dremel off the edges?

1. That would indeed work, but I've been looking for 2.5" PVC/ABS/anything for a while now (for a different project) and have had no luck finding it. I'll redouble my efforts.

2. To be honest, I don't give a fuck. This was more an exercise to practice building methods, and its performance really doesn't matter to me. But I guess I'll bring it to my next war just to show people.

3. All hand tools, oldschool. Made a cardboard template, cut out the wood with a coping saw, and stroked it for an hour with many different files until it reached its climax.


You said "sexy" twice in your comment. I think that means I did a good job.

Edited by BOSS9, 03 January 2012 - 12:45 AM.

[Curly]

1. Since you have Mcmaster you could order 48925K99 for 2.5" PVC. My initial search didn't bring up ABS, but something of that nature has to be there. An ID between 2.4" and 2.5" should be acceptable, just watch the weight.

2. That's understandable, it's a prototype after all.

EDIT:Speaking of practicing building methods, how is the catch holding up? The PR is looking a little thin near the catch notch. 3/4" CPVC instead of 1/2"PVC catch ramp?

Edited by Curly, 03 January 2012 - 12:52 AM.

[andtheherois]

I was wondering, why did you cut the sheath?

[kingjulien]

Dang that's sexy. I've been trying to make a good snap but I've never got one to work. Maybe I could try something like this instead. I might adapt the catch tho. Would this be a little over my head?

[BOSS9]

'andtheherois', on 03 Jan 2012 - 05:50 AM, said:

I was wondering, why did you cut the sheath?

To access the screws holding the spring rest, and so the plunger doesn't have a vacuum behind it when firing. Note the large hole in the PETG plunger tube in the write-up. And the first hole pictured below- both are for venting the plunger.

If anyone cares the middle hole is from a failed idea and the rear one is to access the screw holding on the handle.

'Curly', on 03 Jan 2012 - 05:49 AM, said:

Speaking of practicing building methods, how is the catch holding up? The PR is looking a little thin near the catch notch. 3/4" CPVC instead of 1/2"PVC catch ramp?

There are no problems, but i'm sure there would be if I actually used this, due to the softness of PEX. The final version will use 1/2" nylon rod for the plunger with a washer, standoff, and beveled polycarbonate disc for the catch.
I urge anyone considering this design to use only the design, not my horrible implementation and materials.

'kingjulien', on 03 Jan 2012 - 05:55 AM, said:

Dang that's sexy. I've been trying to make a good snap but I've never got one to work. Maybe I could try something like this instead. I might adapt the catch tho. Would this be a little over my head?

It would probably be over your head, considering you'd have to re-design it with completely different materials to make it useful- and I haven't figured that out yet. A basic snapbow MKV is pretty much the best primary ever, for the vast majority of nerfers. Make one.

Edited by BOSS9, 03 January 2012 - 01:12 AM.

[Zorns Lemma]

Interesting design. You basically took the regular rainbow and moved the catch to the stock instead of the spring rest and put another tube over it?

What are your plans for the real version of this? Apologies for my obvious bias here, but unfortunately, I must disagree with your decisions, because from my perspective, you've added more parts that actually increase the total blaster length to plunger stroke ratio. However, it is aesthetically pleasing with the pump enclosed compared to the standard rainbow pump.

[BOSS9]

'Zorn's Lemma', on 03 Jan 2012 - 11:27 PM, said:

Interesting design. You basically took the regular rainbow and moved the catch to the stock instead of the spring rest and put another tube over it?

What are your plans for the real version of this? Apologies for my obvious bias here, but unfortunately, I must disagree with your decisions, because from my perspective, you've added more parts that actually increase the total blaster length to plunger stroke ratio. However, it is aesthetically pleasing with the pump enclosed compared to the standard rainbow pump.

I don't think I've stressed this point enough- this design is inefficient and pointless (for others), and I don't see why anyone but me would want to build this. However, it fits my style and I like it. Like the PAS and quadshot (and 2-11) the entire mechanism is contained in the shell, fully internal, and does not protrude past the rear handle or front bushing. It doesn't really matter, as the final version will have a stock anyway, but... it fits me. I'm trying to build a primary to end all (of my) primaries. I guess I don't have a better reason than that.

The reason I posted this is to stimulate creative discussion and thought about alternative blaster designs, not to help others build the same thing I have. I fully recognize that it is inefficient in both plunger volume to length and plunger volume to girth. I would encourage anyone interested in an enclosed pump-action blaster to instead build your design.

[Zorns Lemma]

'BOSS9', on 04 Jan 2012 - 12:25 AM, said:

However, it fits my style and I like it. Like the PAS and quadshot (and 2-11) the entire mechanism is contained in the shell, fully internal, and does not protrude past the rear handle or front bushing. It doesn't really matter, as the final version will have a stock anyway, but... it fits me. I'm trying to build a primary to end all (of my) primaries. I guess I don't have a better reason than that.

A fully enclosed blaster improves safety and longevity, and for me aesthetics. I like what you've done here and I'm curious what tube sizes you're going to choose for the final product.

Something you could try is placing the spring between the priming slide and catch, instead of between the plunger head and spring rest. Your catch would become the new spring rest. You would have to attach some sort of disc onto your plunger rod [a la Beaver's pumpsnap], which does add weight, but then you gain the advantage of getting better volume ratios and also you eliminate tensile stress on the plunger tube.

Edited by Zorn's Lemma, 05 January 2012 - 02:28 AM.

[BOSS9]

'Zorn's Lemma', on 04 Jan 2012 - 03:47 AM, said:

I'm curious what tube sizes you're going to choose for the final product.

I've been looking and have been mostly unsuccessful. If only McMaster had a polycarbonate tube with a 1.68" ID and 2" OD, to fit over thinwall 1 1/4" and in 2".

'Zorn's Lemma', on 04 Jan 2012 - 03:47 AM, said:

Something you could try is placing the spring between the priming slide and catch, instead of between the plunger head and spring rest. Your catch would become the new spring rest. You would have to attach some sort of disc onto your plunger rod [a la Beaver's pumpsnap], which does add weight, but then you gain the advantage of getting better volume ratios and also you eliminate tensile strength on the plunger tube.

That's a really cool Idea. Further mental optimization of this just kept leading me to the Fallopian MK2 design. That may be where my project ends up if I can't figure out materials.

Tensile strength of the plunger tube at the screws supporting the spring rest is one of my biggest fears if I were to find my ideal tube. The spring rest would be 1/2" polycarb, so the screws wouldn't be too close to the edge, but that is the definite weakest point in the design. I might have to scrap this plan and fall back on a half-established design with an excellent volume to width ratio, with the priming components arranged vertically.

[Daniel Beaver]

Looks pretty clean for a prototype blaster. I dig the handle, a LOT.

[jwasko]

'BOSS9', on 03 Jan 2012 - 04:54 AM, said:

The reason the popular 1 1/4" 1 1/2" thinwall 2" combo won't work for this is that the thinwall section would be too flimsy. Thinwall just can't hold screws in the way I need it too

The only place I can see screws in the priming slide is where the pump grip attaches. You may have used some to attach the concentric rings which size down the priming slide to where it can pull back the plunger, but I'm not sure.

In both cases you are going to have multiple layers of PVC, so you can solvent weld them together. In particular, you could solvent weld a piece of 2" PVC to the 1.5" thinwall then drive a screw through your chosen handle and into the solvent-welded block.

[BOSS9]

'jwasko', on 09 Jan 2012 - 04:54 AM, said:

The only place I can see screws in the priming slide is where the pump grip attaches. You may have used some to attach the concentric rings which size down the priming slide to where it can pull back the plunger, but I'm not sure.

Everything is held together with screws, you can see one in the 11th picture.

'jwasko', on 09 Jan 2012 - 04:54 AM, said:

In both cases you are going to have multiple layers of PVC, so you can solvent weld them together. In particular, you could solvent weld a piece of 2" PVC to the 1.5" thinwall then drive a screw through your chosen handle and into the solvent-welded block.

The only way I'd use 1 1/4 for the plunger tube is if it was thinwall, and then the screws in the springrest would be a problem. There's enough room between 1 1/4 and 2" to use a much thicker tube, I just haven't found the correct dimensions yet. The final version of this (I'm actually working on a new design now) should be totally bomb-proof, which is why I'm so picky. If you look at the pictures, there's a strip of 1 1/4 solvent-welded to the priming slide in the way you described. It could work, I just wouldn't be satisfied.

[1990cujo]

You posted this the same day i had an idea to create a pas a pump action snap variant the same way you did good job you beat me to it congrats.

[BOSS9]

'1990cujo', on 05 Feb 2012 - 05:45 AM, said:

You posted this the same day i had an idea to create a pas a pump action snap variant the same way you did good job you beat me to it congrats.

Thank you for sharing.

There's only so much you can do with nesting tubes, and many people come up with things independently. We just don't bump month old threads about it.
zing!

Edited by BOSS9, 05 February 2012 - 03:06 AM.