Hello everyone, I haven't posted in a while because I took a break from designing the cannon, but now I have some questions regarding my hope to make a Piston Hybrid! I was looking over my spreadsheet list of parts for my future cannon, and I noticed that the O-Rings that would go on the piston were...

TERRIBLE IDEA. DO NOT ATTEMPT. Meh... It's easy to do if you've got half a brain and an understanding of basic chemistry and physics. In fact, it's done every day using cardboard tubes (hint: fireworks). Beyond that, if anyone has questions I'll answer via email, but I'll respect the forum rules ot...

BAD IDEA First off, this violates section 3 of SpudFiles rules . A simple 9mm's barrel pressure can reach 30,000 PSI. Most firearms reach a pressure of around 60,000 psi. ( http://closefocusresearch.com/calculating-barrel-pressure-and-projectile-velocity-gun-systems & http://boards.straightdope.com...

Or try Exacto knife blades glued to the bottom of the mortar.

I would do what jackssmirkingrevenge suggested and install the Schrader valve on the bottom of the bottle. Use a Simple Truth or other flat bottomed water bottle. Cut a 1/2" hole into the bottle cap and that will be where you rupture the burst disk with a nail or other puncturing mechanism. If you n...

I would use a Simple Truth water bottle as the bottom doesn't have those annoying flimsy thin-walled prongs. Vinegar and baking soda are pretty weak & impractical relative to all the other ways you could achieve pressure. If you aren't hell bent on using CO2, I would install a Shrader valve into the...

Cthulhu wrote:That's actually a really good idea, wouldn't I have to drill another hole and fit in a fitting for the pump though?

I would put the valve in the cap as it's the thickest piece of plastic. The burst disk could be in that small circular bead in the bottom of the bottle.

Also, do you have any recommended changes for my parts list ? Yes, why did you chose the pink stungun? Don't blink when it comes in pink :lol: It was the cheapest stun gun I could find... Honestly, these are probably the most detailed plans I've ever seen a newbie making, and since you've gone for ...

OK- I found a lot of candidates but factoring in that the weld bead will be at least a 1/16 of an inch, I will have to sand down the weld bead a little on the ID as I used this pipe with an ID of 1.93". What should I fill the gap with? Epoxy? JB Weld? Also, do you have any recommended changes for my...

But with the slightest and shortest angle possible so it isn't losing significant compression... I'll probably grease the O ring & Barrel so it doesn't get a ton of friction from the combined increased compression & twisting.

Thanks for replying! Somehow I missed this until now... Ideally you'd want the bolt handle to be at an angle in order to tighten the barrel against the seal. I thought of that but to clarify, like so? (The dark gray slot is the path the handle follows.) http://i.imgur.com/32XySpY.jpg ... but only fo...

Awesome. What speeds and/or penetrating power do you get?

A couple of hours in the workshop working on the new airsoft http://i1034.photobucket.com/albums/a425/farcticox/Airgun%201/Moop%205/MP5%20straight%20chamber%2038%20TEE%20-%20Copy%20-%20Copy_1.jpg Using a limit switch for the QEV trigger, made an aluminum attachment for the switch http://i1034.photo...

So I have a few short questions... the first is, does this still count as a double post if it is completely unrelated? :P Ok ok, the real first question is that I have been thinking about ways I would make my piston hybrid breech-loaded. One way I thought might work is to take a fat high pressure/du...

Use the thinnest wall cross section that isn't fully supported by the cap. The threads create stress risers in the material and you need to further de-rate for those. JM .02 Not sure what you mean by what isn't fully supported by the cap. Are there leftover/exposed threads even if the cap is fully ...