DIY receiver that needs ideas

[djmoe95]

Hello fellow PCP scientists.
Yesterday, I had time to CAD draw an idea that have been in my mind for a few months now. A pcp receiver with adjustable hammer tension, valve spring tension and valve travel. Still thinking about the trigger too. Can you give me ideas on how I can improve this?

 

[sb327]

The design appears functional. Of course it will probably need a cut out for loading.

What is the bottom of the hammer pocket threaded for? Is that how you intend to adjust valve travel, by stopping the hammer? If so, I would avoid that approach unless some type of damping is involved, like an oring for the hammer to hit. Even then, the hammer weight and spring are better ways to achieve adjustment, in my opinion.

Thanks for sharing, will enjoy seeing the other bits when you get them designed.

Dave

 

[djmoe95]

Hello, Dave.
Glad this got attention. The bottom of the hammer pocket is threaded solely for air sealing around valve poppet. I plan to have a M10 plug with 3mm hole in the middle for the poppet pin at the threaded part at the bottom of the hammer pocket. The M10 plug will have a recess behind it to accommodate an oring that'll act as seal around the poppet. The valve travel will be adjusted by the plug in the middle hole. The valve travel adjustment plug will have the same principal as an externally adjustable regulator. The plug will be threaded into the middle hole and the plug will have a M8 threaded hole in the middle in which a long M8 set screw with two or three o-rings will be screwed in. The screw will act as stopper by blocking the poppet travel. I think it'll theoretically be like a poppet travel adjustment. But still pondering on the idea of how to have valve spring tension adjustment.

I plan to make it into .22 cal regulated airgun. I hope to have at least 35 Ft-lb of energy although I have doubts mainly because of the transfer hole from valve to the barrel is only 5mm in diameter. With an 18 inch barrel, regulated 1800 PSI pressure that'll come from a paintball regulator and the bottom hole of the 3 holes at the front acting as a plenum plus a 5 cm tube which act as adapter to have the regulator thread into the receiver, I'm sure 35 Ft-lb of energy is not asking too much except for the air transfer port problem.

Anyhow, I've got a CNC service place machining the receiver which I'm expecting to get it by the end of this month.

Any advice on improvement of this will be appreciated.

 

[sb327]

Some feel there is a need for sealing of the poppet stem. I do not. If the stem guide is long enough, there is very little leakage that occurs there. Just my opinion.

One thing you can do with that being removeable, that I feel is advantageous, is to be able to change stem diameters. Stem diameters have a large effect on the tuning (closing force) of the valve.

Again, I feel hard stops for valve opening distance (in any form) are not a good idea but may be fine for you.

With access to the valve (like you have) you can do other interesting things. Like making an adjustable balanced valve.

Your design is similar to the AEA hp series and I have an adjustable bv in one of mine.

Keep us updated.

Dave