31 replies to this topic

[Carbon]

Here's the next generation of SNAP. I took the improvements of the SNAP 2 (stock, handle-based plunger charging), and solved some of the problems that were inherent in the design (big honking plunger, dangerous piece of metal flying forward). It's missing some finishing touches (like a handle), but it's functionally complete.



The charging rod handle has been moved to the rear.


And here's the juntion between the chargerod section and the PC section. Standard clothespin trigger.


Here's the gist of how this works:

The SNAP-2 had a 1.25" => .5" reducing bushing that held the stock, held the spring in place, and allowed the chargerod to slide past. Really, the only function the rod had in the 2 was two make sure the spring didn't buckle, and all the force was channelled in one direction. The charging handle was directly attached to the plunger, so there was the whole issue of making a slot in the PC, and making the plunger long enough so the head never touched the slot at full draw.

For the 3, I added an inch of .5" PVC to the rear bushing to hold the spring, and then put on a 1.25" to .5" bushing. The chargerod slides through. I have a .75" endcap around the end of the chargerod, to keep everything centered in the rear section of 1.25" PVC, and to give a solid chunk to anchor the handle to.

The other reason I moved the handle to the rear is to solve the whole "fast moving piece of metal when I fire" problem. In this version, the chargerod isn't snugly attached to the plunger, only cotter pinned in place in a loose hole. The plunger is equal in length to the draw of the spring (about 5"). After pulling the plunger back, I can push the charging handle back forward, pushing the chargerod up inside the plunger. That way, the spring is only moving the plunger, and no metal bits. Also, the forward action of the chargerod could be used for action on a breech/clip/magazine.

Irony alert: I made this version partially because I wanted to make it a bit safer, so I wouldn't gouge myself on the charging handle. So what do I do right after I got this one working? Forgot to push the handle back forward, and gouged my arm. Oh well.

Lightening the plunger seems to have given range improvements, as it hit the 80' mark with micro stefans.

Issues: the rod moves a bit stiffly when I shove it back forward....mostly because it's a metal-on-metal contact point, where the rod is sliding past a bunched spring. I need to do something to lubricate it (in a way that won't make a mess). Also partially because I drilled my rear endcap a little off-center, and my slot isn't quite big enough. It should all improve with usage wear.

Stuff to do: a handle (of course), improve the stock, and create a clip system that capitalizes on the back-and-forth motion.

Edited by Carbon, 10 June 2016 - 07:11 AM.

[ompa]

Heh. I had an interesting incident when I brought SOFAR right up to my face to aim down the top of the gun... WHAM the charging rod came and smacked into my cheek. I've been thinking about better ways to charge it, and I was thinking about something like this:



After managing to hit myself twice like that, my next homemade will actually include that feature. I feel for you, getting hit myself a few times by a flying charging handle.

~ompa

Edited by ompa, 12 March 2006 - 06:08 PM.

[CaptainSlug]

You might want to put a weak spring or rubberband on the charging handle so that it returns itself to a neutral position.

[Carbon]

The rod's forward action is a bit too stiff/uneven for a spring to work well right now...but you're right, I'd like to add that. I need to work on making sure all of my parts are centered, and that'll fix some of my binding problems. A ring of ground-out 1.25" coupler could work as a charging "ring" as well.

...hmm, more stuff to work on.

[davidbowie]

I'm eagerly awaiting the completion of this gun. Why? Because it will be really, really cool.

A return spring would be a nice addition. One less thing you have to remember while firing. That's one of the problems with the mini KISS, I have to put the pull-ring back in every time, or else it will whip around and hit me in the chin.

Is this going to have a clip like the SNAP-2? or just a generic clip-loader?

[ompa]

You might want to put a weak spring or rubberband on the charging handle so that it returns itself to a neutral position.

The little squiggly lines represent springs, meant to return it. Sorry, forgot to point that out.

~ompa

[Carbon]

Yeah, and a return spring would have kept the gun from drawing blood this afternoon.

It's the overall goal to make this have a solid clip system. I've made improvements to my last clip so it's a lot more dependable, but I think part of my problem is that I'm still thinking about stefans like bullets, which they're not. Clips and the like don't work as well with things that squish. So I got this idea...

[crazy shit idea]
Do you know the kinds of toothpick dispensers they have at restaurants? The kind where there's a hopper of picks, and a cylinder with a slot in it at the bottom. You rotate the cylinder, and a pick is caught in the slot, rolled through the cylinder, and deposited in a catchtray at the bottom. My thought was to make something like that for stefans....

Take a tube full of stefans. At the end of the tube, there's a larger solid cylinder with a slot in it. Stefan slides forward into slot. Rotate cylinder. The cylinder rotates 180 degrees, stopping at the barrel. Fire. Rotate cylinder to catch a new dart. The same system would work with a stack of darts. My problem with this idea is how to make the cylinder rotate in, and keep everything airtight.
[/crazy shit idea]

Something like that.

[ompa]

Well, if you're looking for something similar to a horizontal clip; I've got something in the works for that. It's in the prototype stages as of now, although it does actually work. It uses the amazing ability of Stefans to bend to its advantage. I can probably get some pictures up and whatnot if you're interested.

Best way to keep it all airtight would be to use shells, and something that would seal the shells, similar to the system on the FAR.

~ompa

Edited by ompa, 12 March 2006 - 07:15 PM.

[Carbon]

Best way to keep it all airtight would be to use shells, and something that would seal the shells, similar to the system on the FAR.

I'm trying to avoid shells....it's more to recover, load, and keep track of, and I want to keep things simple.

I'm interested in the bendy clip...using the properties of stefans to an advantage.

[Ronster]

Well, if you're looking for something similar to a horizontal clip; I've got something in the works for that. It's in the prototype stages as of now, although it does actually work. It uses the amazing ability of Stefans to bend to its advantage. I can probably get some pictures up and whatnot if you're interested.

Like a Halo 2 SMG where you load the clip from the side insted of the bottom?

By the way, Carbon, very nice. I'm really impressed with all that you've accomplished lately.

[boltsniper]

Plunger mass makes a quite substantial difference. I`ve encountered this with the FAR and it becomes apparent when you think about the physics. You want the plunger to accelerate as fast as possible to create the largest pressure behind the dart. So, lighter the better.

SNAP-3 looks pretty sweet. Hurry up and put a pistol grip on that shizzle. How long is it? It's hard to get a good grasp on legnth. There is nothing to compare it too. It looks quite long but then again I can`t really tell that well.

Very impressive work. It will kick some major ass if you do get a clip system on there.

Nice Work!

[The Infinite Shindig]

Carbon, you've definitely been impressing me recently. Keep up the good work.

[Carbon]

Thanks for the kind words, I appreciate it.

I got a handle on it tonight (so to speak)....


I also snapped a...er....SNAP family picture, with an AT2K for size reference:

(Top to bottom: SNAP-2, SNAP-1, AT2K, SNAP-3, SNAP-S)

This is the first time I've used 1" PVC for a handle (I ran out of .75"), and man, it feels substantial.

I solved my spring/chargerod problems, at least short term, by just lubing it up with silicone. It moves much nicer now. Whether that holds is another matter. It's not hard to do, though, as the gun can literally break in half to expose the spring.

Speaking of plunger mass, boltsniper, do you think it would compromise the integrity of the plunger too much to swiss-cheese it, to further reduce mass? Or would the weight savings not be worth potentially weakening the plunger? Or should I just track down some .75" thinwall for the plunger?

Edited by Carbon, 10 June 2016 - 07:12 AM.

[davidbowie]

Oh man... I love that thing more and more. It's got kind of a harpoon gun appearance to it now, which I like. A lot less chunky than most nerf guns.

Yes, 1" for a handle does feel rather beefy. I like it. It fits right into my hand.

I can't wait for a clip on that thing! It will be quite nice.

[Rip32]

Everythings looking realy nice. You have realy white and nice pvc, which makes your guns nice, even with out being painted. Good work!

I also used to use a clothespin as a trigger aswell, on my homemade rubber band guns. They were fun, but I could only make them single shot.

Edited by Rip32, 13 March 2006 - 07:56 PM.

[boltsniper]

You must have little hands Carbon, grips from 1" PVC are perfect for me.

No offense intedned there. Don`t know how sensitive you about hand size....

What size PVC are you using for the plunger shaft? If you don`t go overboard with the lightening holes then you should be ok. The easiest thing though would be to just use smaller PVC for the shaft. Do you have any pictures of jsut the plunger?

[Carbon]

Funny that you mention it, I was just gonna post some breakdown pics.

The plunger is the same as the other SNAPs...two endcaps, and a length of PVC, all .75".


Here's the rear bushing.


And I added a stock out of spare parts. (I need to use an elbow instead of that Tee.)


Heh, no prob, bolt. My hands aren't exactly huge, so .75" works pretty well for me. 1" isn't too big, but it feels nice and hefty.

I've been using .75" for the plunger because of the simplicity of it; it fits in 1.25" PVC already (or rather, the endcaps do). The tolerances are close enough that I can fire it with no O-rings at all, and clear 40 feet. My gasket assembly doubles that, but it's pretty close in there. I started the initial design in the plumbing section, just putting parts togther, and seeing what fits.

EDIT: Just did some looking at lowes.com and found that my local store carries .75" thinwall PVC. (For some reason, thinwall has been hard for me to track down.) I'm gonna pick some up and see if I can lighten up my plunger that way....

Edited by Carbon, 10 June 2016 - 07:12 AM.

[Carbon]

Let's hear it for Lowe's (one just opened by my house). Got the thinwall PVC installed into the plunger tonight, and the results were immediately noticable; I gained 10' on range, up to 90 feet. I don't think I'm gonna try and reduce weight in the plunger any more right now...if anything I'd work on improving the gasket system.

But first things first; now to make a clip system that's effective...and doesn't make the gun 4 feet long.

[Carbon]

Improvements to the bolt system: this is the spring load system I'm using.



It's a piece of 9/16" brass with 1/2" aluminum inside of it. The aluminum is connected to the bolt just through a hole. It's a hook-end spring; one end is over the bolt, and the other is hooked over the end of the brass. When it's drawn back, it keeps the spring covered:



It also builds in a rod that I want to connect to my other breech system (that I showed on the 2). I have a few ideas for how to convert backwards motion into forwards motion, but I need parts. I'm not wild about the retaining system (that's what the zip tie and the pipe clamp are doing). Not only that, but I glues it to keep it straight. I'd like to find a system that keeps the whole thing removable, with no parts glued anywhere...but this things bings like crazy if it's twisted at all. And since it's connected over two parts that can twist...

And since a few people have been asking, here's the current state of the clothespin trigger. I have a piece of .75" pvc glued over the trigger on the 3, so this is a pic of the trigger on the 2 (which is identical):



Main improvements are the plastic clothespin (which bonds better), and the zip ties to help reinforce the glue.

Edited by Carbon, 10 June 2016 - 07:13 AM.

[m15399]

Lookin' good, as always. The trigger looks much sturdier than the original clothespin trigger.

Any progress on the clip/thing? I really liked the fact that the old ones were so simple. You could do something like the Rclip v2, except use yout hopper instead of a peice of pipe. I'll try and explain visually what I'm thinking about.

That's the most baddest drawing ever FYI.



The back peice of brass/barrel material would need some electrical tape to make a good seal with the rest of the PVC (not shown). It's reversed so that you can connect it to the charging rod.

[fobpawwor]

The only problem of a hopper which gravitationally feeds the dart is that it will not always feed a dart. The dart itself will not just drop into your breech for you, it would require some shaking and the dart is too lite to drop into the breech. The best clip I've seen so far is the clip on Boltsniper's FAR, or even more excellent, on the SCAR. So, sorry if this sounds discouraging, but from experience, a gravitational fed hopper wont cut the deal. But keep the designs coming!

[m15399]

All right then be picky.
You can make the hopper vertical for better feed.

You speak from expirience? Got any pics of your hopper? What exactly was wrong with it?

In my humble opinion, Ompa's clip is the best. Negligible range reduction, same ROF as the far, and MUCH simpler to build.

Edit: By the way, you're talking to me like I'm a three year old, and I've been here twice as long as you have.

Edited by m15399, 23 March 2006 - 01:49 AM.

[fobpawwor]

Im just trying to be nice, and not sound mean. I did not know you could take it the wrong way. However, I have made hoppers that are made out of bolsa wood, representing the exact size of the dart. It works okay, but in a war, it broke off and some guy stepped on it. So I have no intention of making another one.
Sorry if i sounded gay, im just trying to be respectful.

[GeneralPrimevil]

"My name's Primevil"
"Hi, Primevil"
"And I...hate...hoppers"


Speaking (well, metephorically anyhow) seriously now, hoppers are tEh ShiT compared to magazines for use with a long projectile. However, a gravity fed magazine is completely different. If Nerf used round projectiles (like non-Nerf activites), then that would be different, kinda...

For what it takes to make a hopper compared to what it takes to make a simple box, just make the box, no? That's just my two cents, but two cents is a lot back in the day...

That hopper reminds me of an R-clip or whatever it's called. That gives me an idea...

[z80]

I was thinking of making really small stephans and they would be able to feed into a hopper evenly. The problem is they would probably be facing the wrong way. :/ I'm working on a turret type clip, meaning that the shells are all attached to each other and move together.