7 replies to this topic

[Foam Shooter]

I have been talking about this for a while and keeping it under wraps. I just started to build it today and made a design for it this morning. Here it is:

Not great quality because the lines are very light but you probably get the idea.

The back.

The middle.

The front.

Right now I'm trying to find a way to make a breech so that when I prime it it opens and closes but nothing effective has come to mind yet. If anyone has any suggestions I would greatly appreciate them. I do intend on building this within at least two weeks but the school year is really picking up right now so no promises.
Suggestions to improve the design would be greatly appreciated.

Edit: Those pictures are awful, I'll go over the picture darker and repost them.
Edit: These should be better.

Edited by Foam_Shooter, 16 November 2008 - 05:13 PM.

[Icespartan 1114]

From what I can see it looks very similar to a SNAPbow. I would like to see this when it is finished, and as you said your pictures are very light so it would be helpful for new ones.

[rork]

Is there a bolt, or does the pump actuate via the barrel, or what?

Edited by rork, 16 November 2008 - 05:28 PM.

[Foam Shooter]

Rork: There will be a 1 1/4" Coupler attached to a 1/2" coupler in the thinwall PVC by screws. There will be a slit going back into the gun. When you pull the coupler towards you, like a pump action shotgun, it will bring the thinwall back which will bring the plunger head back, which will bring the catch back and compress the spring. The catch will catch on the clothespin trigger. At this point you push the 1 1/4" coupler back forward. The plunger head will stay in the same spot. Once the 1 1/4" coupler is at the front again you pull the trigger, releasing the catch, sending the plunger head forward, compressing the air in the empty space of the plunger and this will shoot the dart out of the barrel.

[Carbon]

So, the plunger chamber moves along with the charging handle, and then returns to a forward position after priming the plunger. Nice idea!

I see one weak point. Form the looks of it, the charging handle slides forward, and comes to rest at the end of the slits. So, the force from the plunger hitting home is going to focus on those two spots, whereas a typical design has the friction of a reducing bushing or coupler, plus much smaller screw holes to give it a bit more integrity. I'd be a little concerned about eventual failure at those points.

Aside from that, a pump handle could be a bit difficult to pull, especially with a strong spring. It was my initial plan to put a pump handle on the SNAP-4, but the push wasn't practical...and that was only an ACE #62. You may have to modify your pump handle to give yourself a bit more leverage.

[clutchjunkie]

I am working on a homemade that cocks similar to this right now, and I have to say that so far it's been kind of a pain in the ass. I am using a clip loading brass breech with mine and I had to custom machine an aluminum "dart pusher" tip to push the dart forward and then seal against the brass with an o-ring. The biggest problems with my design so far are the clearances for the catch/spring/plunger rod, I am making this homemade to be a replica of something and space is a little limited.

All I am going to say is draw and measure everything out very carefully before you start cutting. You're going to run into some surprises with the whole moving plunger tube thing.

[Quilan Fett]

Having made several guns similar to this, I have some advice:

The back to the plunger tube is unnecessary.

Instead of working for a seal between the plunger tube and breech/barrel, connect them and have a moving plunger tube.

For the breech, I'd just do a simple one and forget about a clip. They are too hard to get working right and their jamming overshadows their speed.

[Draconis]

I've been thinking of something similar to this myself. Perhaps I need to move forward on it and see if I can be of some assistance.