The Craftmans Shop > Backyard Ballistics
Spring air rifles
doubleboost:
Thanks for that is bronze good for a spring guide
Nice and tight inside the sprina as it expands when compressed i asume that is the idea
John
Jonny:
Use steel polished up so that the spring wont go on unless its twisted and compressed by hand.
Make it a one piece, can add a bearing but limted to the cross pin in the Beesa. The guide could or would deflect in a vertical movement still. If yo can stop this could see gains of 10%.
keithomas:
i "tune" or "play" with hw80s. their an easy thing to squeeze more power out of. over 12ftps is illegal, your ass is going straight to jail if your cought with it. got a couple of interesting builds on at the moment. one has a 30mm internal scrape out. sides are now parallel. the piston has been chopped down and delrin buttons. the 30mm parallel sides with the delrin buttons make it silent and no lubrication will be needed. its also got delrin piston guide which is mated in to the back end , delrin twist washer and delrin top hat.the piston also has a ptfe sheet in it to keep the metal noise down. I've all the bits to finish it but, I'm in the middle of building a workshop so all my toys are on hold
Jonny:
Junk the acetal, it flexes and worthless for its intended purpose.
the only reason acetal is raved about and used, think logically and between the lines. Its marketing! As in 5 min job as a one off for an HW80 in delrin, but same machine using steel looking at 1 1/2hrs, see where i'm coming from people are mugs and believe the marketing.
Then add delrin isnt stable in size, has more grab therefore more friction as the spring gouges in to it with greater surface area.
Prone to breaking as well, certainly with 10mm+ bore and 13.5mm+ o/d = 1.75mm thk wall 2.1mm tops!
Then add it flexes not keeping spring in a straight line, what you dont want.
Steel would have less friction due to lesser surface area and coeficient of friction any way. You tried moving a ton machine digging in to soft material such as wood or delrin, it dont slide. Using steel to steel machine slides easilly, similar to the compressed spring wanting to buckle or veer off!
Anyone with any engineering practice will agree to highest level.
doubleboost:
Hi
I made a spring guide for my HW 80 out of a bit of en8
It was a tight fit on the spring (screw on tight)
Taperd the transfer port polished the piston and honed the cylinder
I had to cut 3 inches off the spring to get it legal
Now it is a dream to shoot
Very easy to cock smooth and quiet giving a constant 11.5 ft lbs
It was well over 25 with a Webbley venom spring before i cut it
John
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