Winchester Air Pistol Seal

[Harold_V]

Hy-Score 700 and 800 were US made. Then they started importing from Germany. The 815 (like mine) and also sold under Winchester name were made by Diana of Germany. Same as Diana md 5.

Still no love on finding a piston seal.

All help or tips appreciated.

I don't have a clue what it looks like---but have you explored the piston seal on little (12volt) air compressors? Much like a cup in a wheel cylinder.

Harold

[ken572]

Dave,

1) I would try to machine one out of a piece of teflon, or hard urethane.
2) Machine a inner/outer mold and fill it with silicone/liquid rubber etc.
3) Cut some oil soaked leather and press it out on a wood form etc.
4) See below..

Diana Model 5 - TEARDOWN
http://anotherairgunblog.blogspot.com/s ... Modell%205

http://www.polyneer.com/PDFs/Wheel%20Cylinder.pdf

http://www.crown-rubber.com/google/inde ... gwod_Q9Gpw

http://www.coorstek.com/products/seals. ... gwodtVAXnw

http://www.labsafety.com/search/stopper ... oButton=Go

http://www.medibix.com/company.jsp?company_id=16796

http://lynnnoyes.com/how_to_measure.htm

Ken.

[ken572]

Dave,

Did you ever get your seal problem solved??

Ken.

[mechanicalmagic]

Ken,
No, I did make a few piston seals. The first was too long and was destroyed in short order. The second lasted a few weeks. I haven't gotten the pistol back to determine the cause of failure. I suspect my choice of materials, I think I used some PE.

Dave J.

[ken572]

Dave,

I think the use of poly-ethelyne and/or poly-propelyne might
not be the best choice to use in this application, because it
has a very low melting point because of the parafin in it. PVC
and CPVC might also be a poor choice for the low temp reasons.
You might want to try Teflon or some old shoe leather that you
soak in a hot oil bath and then try to shape it over a wood form
etc. If I remember correctly the old Sheridan pump rifle used a
leather pump seal, as well as some of the older carburator
accelerator pump seals. This makes me think that maybe you
might want to go to the auto parts stores and see if you can
find either a accelerator pump seal in leather or the new synthetic
type in the size you need for your gun.

Ken.

[mechanicalmagic]

I don't stock Teflon that large in diameter. IIRC it's near 1" diameter, and has a nub to hold the seal onto the driving piston. The other issue was the shape. I thought it needed to be fairly thick, to take up space in the pump, when the piston bottomed out. I only had some dried out remnants and small chunks to go on. Nothing with any real shape.

Next time I go by the kid's house I'll pick it up, and get some dimensions.

Dave J.