You also have to consider the fact that only broadheads are used in bowhunting. A decent bow shooting a broadhead will make a lot of damage, huge external wounds compared to a firearm wound, and this is why bowhunted animals usually bleed to death instead of dying instantaneously. I personally have ...

Has anyone tried to cast a piston out of this stuff? http://www.instructables.com/id/Making- ... dly-Plast/

It look like it could be solid and lightweight.

1/4 Diameter will give a port area = to the cross section of the barrel. This gives in essence two restrictions choking flow of the same size, the barrel area and the port area from the chamber through the gap into the barrel area. I prefer to use a port area that is about twice the cross sectional...

I know a guy that made a QDV with nothing more then a copper T fitting and couple of connectors on either end. For the piston, some all thread, washers and thick rubber gaskets. You dont need a drill press or a lathe... or soldering equipment... I'm sure it could be done with threaded brass fitting...

I'm confused here. If you're planning to build a QDV in the first place, why not use it as the main valve? I think he just wants to have an efficient pilot valve for his piston. The QDV probably struck him as a good idea. That's right. I would like to use a QDV as primary valve, but I cannot (or it...

FighterAce wrote:I use a schrader as the pilot... this is my hammer for it



Check this thread for more info

And the earlier version here on spudfiles

I really like it, I may be going with a design similar to yours...

Good, so using a QDV as pilot can be done. On the other hand I understood that it would be better to use it as primary valve, but I could have some problems, due to the fact that I am restricted to off-the-shelf parts and a dremel, not to mention also design issues and the ability to have bolt or ca...

Hey guys, as you maybe already know thanks to another post, I am bulding another piston valve gun. I'm really trying to get the best efficency using off the shelf parts and found an interesting and efficent solution in order to pilot my piston. The design is based on tech's QDV and is also surprisin...

Thanks for the help everyone. Yes, I could go for a 2 stage pump, I have already build one that cold take my old 16 mm piston gun to 18/20 bar but it really was time consuming, and for this gun I am planning for a large resorvoir in order to have multishot capability. The maximum diameter I planning...

Thanks saefroch!
When I will be done with my exams expect some true POWER
(if I can find a fridge....)

Hi guys,
I was thinking about making another medium piston gun, all copper and galvanized steel, does anybody know if it is safe to use 1" galvanized tees and pipes at 30-40 bar?
Thanks

Hi I had the same problem on my piston gun. I finally found out a way to make a piston that works really well. I took a threaded rod the leght of the piston, 3 washers , some bolts, super glue and two rubber disks a bit bigger than the fitting the piston is in. 2 washers must be the size of the fitt...

It works exacly like that, just had to think a bit to find out. I changed it and now it works, but I still have leaks from the barrel. I use a neoprene washer as sealing face, but it doesnt seal properly, do you know a way to fix that? And also, the bigger the difference in sealing surface and pilot...

Thank you so much.
I thought that was the problem but I wasnt sure.
Thank you both

Hi, I have got a problem with the small metal piston gun that I built. It was actuated by a ball valve, thanks to your help I upgraded it using a modded sprinkrel valve instead. The proble was that the valve was too big for the gun (1 inch compared to the 1/2 inch gun) and that it could sustain only...