SB15 was interested, but nitromethane dissolves ABS quite readily. I am interested, but I have no nitromethane (and, given my relationship with the authorities, should probably continue to have no nitromethane...). Apart from us, I've not heard anyone else mention it. GasEq certainly predicts great...

It is a very interesting topic, and I have though about it myself. However, if I were to use Gasoline injection, I would do it with a pressurized fuel line and an automotive fuel injector. It seems, to me, that this would be far more useful in a hybrid cannon, but could easily be incorporated into a...

Your idea is more or less identical to the operation of barrel sealing piston valves normally operate. There is a pilot volume behind the piston that is exhausted, creating low pressure behind the piston that allows the pressure in the chamber to rapidly push the piston back. Tons of designs out the...

That is probably DWV pipe but the V didnt print. I dont believe there is DW pipe. Even though it is rated, it is probably cellular core, which is not safe to use.

reasoning? Its thick rubber, I am going to super glue it to the face of my piston...

Was the piston lubricated? also are you sure that the pilot chamber is pressurizing properly? It could also be the pilot volume not venting fast enough, is the sprinkler valve modified, or are you using the electric solenoid? Do you have a bumper behind the piston to stop it from smacking into the b...

Goats spudz wrote:The taps i use cost around $40

Cool

dewey-1 wrote:There are taps for NPT and NPTF. The F is used for fuel applications.

http://www.maritool.com/Cutting-Tools-T ... index.html

Hes looking for air compressor fittings, NPT.

Yep 1/4" NPT is what your looking for. I got a tap at ACE, but it was like $8
Please dont get a tap and die set at harbor freight, its cheap, but it cuts crappy threads. Craftsman has sets, but they are pricy. I would try a place like ACE or a quality one online (read $5+ dollars) :wav:

I saw that people had difficulty finding it. I was like, Da Faq?

For anyone who is wondering, SDR-21 in the 1 1/2in variety is perfect for golf balls. I found it at Menards, unfortunately, it is only sold in 20' lengths
http://menards.com/main/plumbing/rough- ... c-8571.htm

until I have a final design, I see no reason to buy acetal stock to make a custom piston when I can do essentially the same thing with things I already have laying around. However, the final version would definitely benefit from a one piece machined piston.

At this stage I am still prototyping, I will possible machine a one piece piston eventually. However, I have the acrylic and the pvc, and the pvc will fit so perfectly in the tee, it isnt worth the cost and effort to machine the piston at this point.

Welcome to the forum :) Here's how I would make it, a lighter piston opens quicker, puts less stress on the bumper and you gain some barrel length too. Of course it would depend on your barrel diameter because you might cause a flow restriction if the barrel is too wide. The outlet pipe is 2" runni...

Hi, I'm new to the forum, but I have made a few spud guns before. Most of the valves designs I see on this site and others use a sleeve inside of a PVC tee. I thought up this design and will be building and testing in the next week. My design bores out the "Lip" inside of the PVC tee so that a 3" pi...