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Topic: SABRE - Semi-auto, but really easy

Given that a few others are discussing their contest entries at NerfHaven, I thought it might be worthwhile to discuss my planned entry in semi-private here.

I had planned to do an air gun even before VACC's offer was made. This is no surprise. In fact, the basic idea behind the gun I'll be making I thought of last year and discussed in some detail with YakMan on IRC. I had assumed YakMan would make a gun along the lines we had discussed, but life seems to have taken over and that hasn't happened yet to the best of my knowledge.

My basic idea is summarized like this: LRT + QEV + DCV + hopper. My basic idea is to use latex tubing as an air source along with a DCV and QEV as the firing system and a hopper as the advancement mechanism. SABRE stands for semi-auto, but really easy, and that encapsulates my goals here. I am looking to bring semi-auto air guns to the masses.

Latex tubing is being used very intentionally. In the past I decided against using latex tubing for my high energy efficiency Nerf guns as they don't have very high pressure, but as efficiency is not a high priority here, latex tubing's other advantages help. The price will be lower than a regulated system. Latex tubing is simpler than a regulated system. Perhaps most important for this contest is that the pressure of the tube can not easily be increased without someone noticing. This should help with those who are completely scared of air guns and the possibility of increasing the pressure without anyone knowing.

The basic structure of the gun is set. I intend to use telescoping PVC pipes as the superstructure. The inside tube will be a container for the latex tube and the outer tube will be a tracked pump. This, at least, is the goal.

I had debated whether or not I should use transparent tubes as I would be able to check how full the latex tube is more readily, but I decided the costs made it inappropriate for this contest. This is certainly an option for those without a limit on costs.

I'm going to assume the latex tube 5234K83 on McMaster-Carr is okay for this project, but later I will test other tubes to see if I can keep the same performance and get more shots per fill.

I've also decided what pump I'm going to use: http://www.amazon.com/Gamecraft-MSHNINF … B0000BYSQE

I can use ball pumps because my pressure is far lower due to the use of latex tubing.

That's basically all I've planned so far. I'm going to start thinking about how to place everything well.

I'd appreciate any thoughts.

Re: SABRE - Semi-auto, but really easy

Sounds like a cool project that nerfers will welcome.  If I'm picturing it correctly, why not cut a viewing window out of the latex tube's container to see how full it is?

Re: SABRE - Semi-auto, but really easy

That's a possibility. I need to see if that can be done in a way that will not contribute to the wear of the tube or make the system unsafe if the tube pops.

Re: SABRE - Semi-auto, but really easy

Or simply use clear PVC/Polycarb/Butyrate, etc.  How wide will that tubing expand to without bursting?  1.5" OD clear vinyl tubing is cheap, and fits tightly in to 1.5" Sch40 PVC.  You may be able to simply line the outer tube with it and have an edge-free window.

Last edited by Draconis (2011-06-10 20:04:28)


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Re: SABRE - Semi-auto, but really easy

Draconis wrote:

Or simply use clear PVC/Polycarb/Butyrate, etc.  How wide will that tubing expand to without bursting?  1.5" OD clear vinyl tubing is cheap, and fits tightly in to 1.5" Sch40 PVC.  You may be able to simply line the outer tube with it and have an edge-free window.

Very good solution.  Reminds of the rim tape used to protect tire tubes in bike trials since the rims are drilled all over the place.  You may even be able to get away with several layers of packing tape or a strip of plastic from a soda bottle.

Last edited by PVC Arsenal 17 (2011-06-11 04:21:16)

Re: SABRE - Semi-auto, but really easy

Oh, the PET bottle section would be perfect.  Just glue it in to place.

Re: SABRE - Semi-auto, but really easy

I've changed the design a bit.

The pump will be on the bottom. I'm going to make a homemade pump from 1" PVC and with a 1-1/4" PVC handle that tracks over the 1" PVC. The 1" PVC will be both structural and functional. A clear 2.5" ID PETG tube will house the latex tubing.

Hopefully I'll have some time during the coming weekend to work on this.

Re: SABRE - Semi-auto, but really easy

The current plan is to buy all the parts I think I'll need this week and tinker with them on the weekend. With luck, I'll have a working gun.

I now have two wyes, courtesy of Split.

I'm changing the design to have a long chopper.

Everything else should be about the same. I'm shooting for 10 semi-auto shots with at least 70 feet of range.