Search found 106 matches

by grumpyoldman
Mon Aug 10, 2015 2:49 am
Forum: Pneumatic Cannons
Topic: Does volume matter???
Replies: 18
Views: 3383

Re: Does volume matter???

eli_ess wrote:Just made a little video to show you all the power of my latest 7-foot-long model!
Cool! I love discharges! :D
by grumpyoldman
Tue Jul 28, 2015 2:35 pm
Forum: Pneumatic Cannons
Topic: Does volume matter???
Replies: 18
Views: 3383

Re: Does volume matter???

Welcome to Spudfiles, Eli. You probably already know this but since you said you were a newbie, I thought I should include this in the discussion: The weight, shape and position of your projectile can also be a factor. Make sure your projectile is of sufficient weight and large enough to fit snuggly...
by grumpyoldman
Fri May 29, 2015 6:34 am
Forum: Pneumatic Cannons
Topic: It's never finished...
Replies: 4
Views: 1905

Re: It's never finished...

Really good job! What's the brand name of the regulator you have your CO2 bottle? Any problems with it? I'd like to try one out. Thanks!
by grumpyoldman
Sun Dec 21, 2014 4:16 pm
Forum: Pneumatic Cannons
Topic: Blow Hard T-Shirt Launcher
Replies: 13
Views: 3759

Re: Blow Hard T-Shirt Launcher

Also random question but does it dry fire effectively? It looks like it would need a significant barrel back pressure to compress that spring in between the sealing faces and since the barrel itself wouldn't really provide any back pressure (being significantly larger than the piston it looks like ...
by grumpyoldman
Wed Nov 26, 2014 4:51 pm
Forum: Pneumatic Cannons
Topic: Blow Hard T-Shirt Launcher
Replies: 13
Views: 3759

Re: Blow Hard T-Shirt Launcher

Any chance you'll put two elbows on the blowgun and add a front grip to shoot it minigun style? :D There's a very good chance of that. :) Using the rods as guides for the piston is brilliant! :D Knowing your ability for efficiency and simplicity of design, I had a feeling you would appreciate using...
by grumpyoldman
Tue Nov 25, 2014 5:04 pm
Forum: Pneumatic Cannons
Topic: Blow Hard T-Shirt Launcher
Replies: 13
Views: 3759

Re: Blow Hard T-Shirt Launcher

Thanks, Gippeto. It means a lot getting recognized by my fellow spudders! Kinda weird to have the regulator on board instead of on the bottle but I guess that's no big deal. Thanks for the compliment. The reason the regulator is on board is because it leaks when screwed on the CO2 bottle. Cheap Chin...
by grumpyoldman
Mon Nov 24, 2014 1:16 pm
Forum: Pneumatic Cannons
Topic: Blow Hard T-Shirt Launcher
Replies: 13
Views: 3759

Re: Blow Hard T-Shirt Launcher

A little note on the spacer which holds the piston centered in the large portion of the chamber, since the photo's resolution is a little low... is that aluminum (or a softer metal than steel)? I would be worried about scratching channels into the inside of the chamber. Good catch. The stabilizer w...
by grumpyoldman
Sun Nov 23, 2014 10:49 pm
Forum: Pneumatic Cannons
Topic: Blow Hard T-Shirt Launcher
Replies: 13
Views: 3759

Re: Blow Hard T-Shirt Launcher

Wow that looks nice. Can tell a lot of time and effort when into the design to make sure it was safe and worked properly! Did you have any trouble sealing up the threaded rods? What regulator is that Looks to be a handful :) Thanks! The rods are sealed using high pressure sealing washers. Seals up ...
by grumpyoldman
Sun Nov 23, 2014 8:33 pm
Forum: Pneumatic Cannons
Topic: Blow Hard T-Shirt Launcher
Replies: 13
Views: 3759

Blow Hard T-Shirt Launcher

I finally finished the first stage design of my t-shirt launcher. It operates at up to 300 PSI with a 10:1 safety factor. Later I will add a homemade pilot valve, homemade regulator and homemade flow valve. There were five basic requirements. It had to be safe, inexpensive, hand held, light-weight a...
by grumpyoldman
Thu Nov 13, 2014 6:43 pm
Forum: Pneumatic Cannons
Topic: Need Help With CBV Design
Replies: 8
Views: 1973

Re: Need Help With CBV Design

You might be OK with the port piston O ring in the smaller diameters if you don't use a floating o ring. My initial tests of a 2 inch floating o ring in that configuration resulted in loss of the ring on shots above ~60 PSI. Non floating ring designs tend to get stuck and fail to fire reliabily. I ...
by grumpyoldman
Wed Nov 12, 2014 10:12 pm
Forum: Pneumatic Cannons
Topic: Need Help With CBV Design
Replies: 8
Views: 1973

Re: Need Help With CBV Design

Hey, Jack. I wanted to experiment with using counter-balanced valves like BTB's pilot valve but make it a main valve. I also wanted a small pilot volume. To explain how it works (if anyone wants to know), I'm going to refer to the back piston as the pilot piston and the front piston as the port pist...
by grumpyoldman
Tue Nov 04, 2014 7:41 pm
Forum: Pneumatic Cannons
Topic: Need Help With CBV Design
Replies: 8
Views: 1973

Re: Need Help With CBV Design

Thanks for responding, Chris. I figured out what was wrong. It was something super simple. I didn't turn the air off when I tried to fire it. The pilot area was filling up as fast as the blow gun was letting the air out. :oops: Now I need to make a few adjustments and I'll be ready to make my t-shir...
by grumpyoldman
Mon Nov 03, 2014 8:53 pm
Forum: Pneumatic Cannons
Topic: Need Help With CBV Design
Replies: 8
Views: 1973

Need Help With CBV Design

Hey everybody. I've got a problem that I hope you guys can help with. I've been trying to design a counter balanced valve and ran into a problem that I can't figure out. When I push the handle on the blow gun, all the air in the chamber comes out the blow gun. It's probably something simple but I ca...
by grumpyoldman
Sun Oct 05, 2014 3:30 am
Forum: Pneumatic Cannons
Topic: Using the Gas Gun Design Tool
Replies: 6
Views: 1041

Re: Using the Gas Gun Design Tool

Try this:
Right click on the ggdt.exe file, you should see a menu. On that menu, click on "Open as Administrator".
by grumpyoldman
Fri Aug 15, 2014 11:55 am
Forum: Pneumatic Cannons
Topic: Commercial T-shirt Gun
Replies: 17
Views: 1979

Re: Commercial T-shirt Gun

I would advise against it, you might get more shots per fill for a given tank volume using CO2 but HPA/Nitrogen is much more consistent and kinder to your internal components. I would rather use HPA but in a commercial launcher I believe it should be able to use both. HPA bottles are much more expe...