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Valve mod - pcp pistol
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Pauly5 View Drop Down
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Posts: 1440 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Pauly5 Quote  Post ReplyReply Direct Link To This Post Posted: 04 Dec 2024 at 3:49pm
I had a good drill bit, but too much speed. Have got a couple of good 135 deg cobalt bits from Sulco now.

Appreciate the help guys.
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Pauly5 View Drop Down
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Posts: 1440 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Pauly5 Quote  Post ReplyReply Direct Link To This Post Posted: 05 Dec 2024 at 10:01am
Quick update on drilling. New bits arrived, halved drill speed, used new paste and it cuts like butter. 

What a relief, I was starting to hate stainless.
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kruzaroad View Drop Down
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Posts: 2360 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 05 Dec 2024 at 10:25am
Lol.
Sweet Pauly. Be a shame to have to use a less durable metal.
Looking forward to progress resaults on pistols now you've beaten this problem.
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JasonEdward View Drop Down
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Posts: 126 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JasonEdward Quote  Post ReplyReply Direct Link To This Post Posted: 05 Dec 2024 at 12:24pm
Yeah I thought a nice sharp drill was all i needed to drill S/S.
Blunted drills, hardened stainless and a fitter mate taught me the error of my ways.

Cry
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BC_Clark View Drop Down
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Posts: 7 		Post Options Post Options   Thanks (0) Thanks(0)   Quote BC_Clark Quote  Post ReplyReply Direct Link To This Post Posted: 23 Dec 2024 at 8:48pm
Looking good Pauly. Pity about the radius cutter not being as advertised.

The inlet screw does not really need the flat down the side and it causes more stress on the o-ring
to force it around a non-round shape. The air flows past a regular screw anyway
but if you must fill faster you can get a similar effect by oversizing the tap drill to 4.5 for M5 and 
leave the screw standard.

When you have stainless parts with a lot of machining time in them and the fastener
isn't working close to its capacity, it is advised to use larger tap drills to avoid broken taps.
Just adding 0.1mm can go from from walking on ice, to a walk in the park.

Anyone not having fun with stainless should try 303 grade for machining.
Not only stronger than 304 and 316 but much nicer to machine.
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BC_Clark View Drop Down
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Posts: 7 		Post Options Post Options   Thanks (1) Thanks(1)   Quote BC_Clark Quote  Post ReplyReply Direct Link To This Post Posted: 23 Dec 2024 at 9:11pm
The main thing with drilling stainless is high feed and lower speed.
It is not the heat that hardens stainless. Regular 304 and 316 are non heat-hardenable.
They only become softer with heat. But they work-harden very readily (316 moreso).
So applying too little pressure to the drill causes it to skim along the surface
without starting a chip. This work-hardens the surface you're trying to drill.

The problem with heat is that it blunts the cutting edge of the drill
which leads to work-hardening of the stainless, accelerating the issue.
HSS with cobalt can handle higher temperature.
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Pauly5 View Drop Down
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Posts: 1440 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Pauly5 Quote  Post ReplyReply Direct Link To This Post Posted: 25 Dec 2024 at 11:07pm
I got a little bit more done today. Enough to fill and fire. I had been having trouble getting the poppet valve to seal. I was trying to get angles to match to no success so opted for a polished flat sealing surface which worked.

Here's  photo and it's first chrony reading. there's still a lot to do, but it's nice actually firing it now. 

Just over 15 ft/lb at around 1200 psi in 25 cal. 
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J-S View Drop Down
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Posts: 432 		Post Options Post Options   Thanks (1) Thanks(1)   Quote J-S Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 9:05pm
It’s looking great! Healthy power too
J S Airguns
Air Arms TX200('s)
Theoben Sirocco
HW77
FWB 300s
Webley Patriot
One or two others...

Current projects:
Too many..
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JasonEdward View Drop Down
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Posts: 126 		Post Options Post Options   Thanks (1) Thanks(1)   Quote JasonEdward Quote  Post ReplyReply Direct Link To This Post Posted: 7 hours 53 minutes ago at 2:07pm
Nice work - looks great!
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