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Old 11-26-2012, 01:15 PM #1
Boom Master
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Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Brainstorm HOW to build a Nerf Belt Feed

Decided to go for the holy grail. Autoloading Belt Fed Launcher. But I need some brainstorming and nitpicking by you guys to help me.

I've been tinkering around with the two basic hurdles that are mechanically very closely related and interactive with each other...


1. Manufacturing the Belt I'm limited to non-machined parts. Wood, plastic, hardware store stuff.

and

2. Indexing the cartidge in the belt to align with the barrel bore.

So far, my thinking is a gear of sorts that drives the belt cartridges made out of schedule 40 PVC. Six gaps between the 'teeth' for the cartridges and rotates 60 degrees for each shot fired.

When the firing cartidge is top dead center and aligned, it will be located left and right with the teeth in a V shape. To make sure it does ride UP on the teeth and is located all the way into the gap, I thought a pair of springs pressing down on top that is made out of piano wire to hold it DOWN in position would be least likely to jam. One pressing on the front and back quarter of the cartridge. Could add more springs in between if needed. Thinking STEP Motor for indexing the 60 degree turn. Anybody know anything about step motors and controls? I know squat.

Some givens on the belt design. It has to roll up or fold nicely out of and into a ammo box. It needs some flexibility or NOT??? at the hinge. Not to roll up but the other direction. If you laid it flat on a table, you could flex it so it doesn't lay in a straight line. Seems some flexibility would keep it from jamming OR just the opposite. Any thoughts?

Still, you have to fit the gear teeth and I think I want the gear teeth to be between the cartridges about 2/3 up the radius of the cartridge. That means I have to have a gap for the teeth to fit into between the cartridges. About 3/8" eyeballs to be about right but that forces the hinge to be at an angle rather than 180 degrees opposite the next hinge. More like 120 degrees fits the gear teeth. That creates a problem in that the belt can't fold in a Z pattern and forces me into a rolled up configuration for the belt that may be a lot harder to pull up on to feed the autoloader. With a Z folding pattern, you only have to lift the top row rather than unspool the whole belt. Instead of an ammo box, I think I would have an ammo spool on bearings on the feed side. Could live with a receiving box for the empties.

If you wanted the Z pattern, the hinge pattern would have to be at 180 degrees from the opposite hinge to fold BOTH ways and the gap between the cartridges would have to be quite a bit wider to allow a 45 degree angle folded. Maybe and inch or so.

I'm really kind of stuck here short of actually building a partial belt and see what works and doesn't work. Need your ideas here.....

Now actually building the belt. Had some success tinkering with using zip ties around the PVC and 3/8" diameter O rings inbetween. If you want flexibility, you have a LOT of it. Otherwise, I'm looking for a piece of hardware the right length to be held with the zipties. something like [] this or a key ring, etc.

Super Glue secures the zip ties nicely from sliding around BUT it seems to make the plastic of the zip tie BRITTLE. Just broke when I twisted it. May try some other adhesive to keep them from sliding and getting loose.

Other thoughts on belt fabrication and design included 3 one inch ribbons or cord like those chinese puzzles. Kind of woven together with a solid round spacer inbetween the PVC cartridges. Again glue/screw the ribbon to each cartridge to keep it from sliding around and getting loose.

I tried to sew a pod holder made out of 4" elastic material. Was a nightmare to make and the elastic stretched out and didn't last very long. But maybe a belt would actually be easier to sew. Just experiment with how far apart your seams have to be and sew two flat pieces together. But the spacing inbetween the cartridges would be awkward to make and sew.

I can't really move too far forward without making the gear drum first and mounting it in a box. Try to make a belt that will work in it.

Well, that is my thoughts so far. Your ideas? Please.
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Last edited by Boom Master : 11-26-2012 at 01:26 PM.
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Old 11-27-2012, 03:01 PM #2
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Have you looked at using something like the below? I've looked at it and played with the idea of cutting the long part and attaching it with some type of rings or hinges. Just didn't continue since I didn't find a use for a belt fed launcher yet.

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Old 11-27-2012, 05:45 PM #3
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How would you ensure that there would be a good seal between the belt cartridges and the barrel of the gun when you're ready to fire?

Also, I think a rigid belt that feeds vertically like a magazine from straight up under the cannon might be a good configuration. Rigid belt to ensure the cartridges stay indexed properly.

A belt fed system would almost certainly be for a tank right? Or do you intend for this system to be incorporated on a LAW?

Finally, good topic. I like where this discussion is going!!
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Old 11-29-2012, 11:04 AM #4
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I'm getting old and I'm hauling enough weight around in my walking tank which is getting heavier and heavier every year. It will wind up in my first motorized tank. BUT whichever gets built , it may not be practical but it will be field tested somehow. As a hand held, fixed emplacement for HQ defense, or in the walking tank. Or in the motorized. I just have too many things I want to build that just won't all fit in a walking tank.

The autoloader belt feed cannon will be built off my 6 shot magazine autoloader design. A piston pushes the cartridge forward against the breech of the barrel and holds it long enough to get the nerf up to speed and out of the barrel. It is just PVC flat against PVC for a seal so it leaks some. You have to trade off the air efficiency some for the ROF and loading mechanism. The whole 6 shot magazine moves back and forth about a quarter inch. Why the belt feed needs SOME flexibility to be shoved maybe an 1/8 inch forwards and backwards. Just enough for clearance to rotate and feed the belt.

Have been pondering ways to add a seal on the piston and barrel breech end. Probably a flat rubber sheet glued to the board on the barrel breech OR an O ring/gasket. Ditto on the piston side.

Haz, good idea! I will go eyeball those a bit closer and see what works. looks like a good spacer with a hole in the middle for a couple of zipties to go through. I discovered over the years that you cant have too much firepower. I have said, " If I can't hit what I'm aiming at in 6 shots, I need to get closer or practice more.... The SECOND game of it's existance was up at Sherwood?? Got orders to DESTROY the Castle which took four shots on each wall and the tower. Took 20 shots and my last shot went about 6 feet out of the barrel but hit the wall. I was running out of air two shots back...

I had to eat my words about 6 shots being more than enough and started thinking about a belt feed on the way home from that game.... I

went right out and bought a 25 pound, 513 ci x 3,000 psi air tank in the walking tank. Haven't run out of air since..

Since, I have found many practical uses for a 6 shot magazine and wished for more. For example, with the breech loader with a fire rate of one nerf every 4-5 seconds gives you just ONE shot at an attack helocopter coming to take my tank out. Had to wait until you see the whites of his eyes.

With the 1 RPS autoloader, I can open up on him at 25 yards and make him start thinking about wearing a cup next time he decides to be a helicopter. Makes him zig and zag running like a tight end through the backfield. And you miss a LOT. 6 shots and no kill, makes you DREAM of a 40 shot belt feed and TWO rounds per second.... When we roll onto an objective with 20 infantry and my walking tank, I know they have a bazooka when the kids don't run away. It is nice to just blow up every bunker in sight to try and get the bazooka and any infantry in them. Clean house. ASAP.

You will find ways to utilized more firepower once you have the capability. Not to say you can't have FUN without it.

MORE ideas guys and gals...!!!!!
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Old 11-29-2012, 05:35 PM #5
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You can find them at Lowes. It does hold the 2" pvc pipe very tight once snapped on.
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Old 11-30-2012, 12:46 PM #6
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Oh! ? Use use that pipe hanger to mount the pipe in and use one of the holes as the hinge point. Cut off the excess. Has potential. I see what you are getting at. Keep the ideas coming.
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Old 12-02-2012, 10:30 AM #7
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http://www.onlinemetals.com/merchant...7 3&top_cat=0

7' length for about $43 plus shipping will give you a 12 round belt with a cutting saw or even a hacksaw if you're careful.
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Old 12-02-2012, 12:11 PM #8
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Hey, TJ Good resource. In my favorites.
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