Valve mod - pcp pistol

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   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 Members Profile Send Private Message Find Members Posts Add to Buddy List Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1439	Post Options Post Reply Quote Pauly5 Report Post Thanks(0) Quote Reply 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.

Pauly5 Members Profile Send Private Message Find Members Posts Add to Buddy List Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1439	Post Options Post Reply Quote Pauly5 Report Post Thanks(0) Quote Reply 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.

kruzaroad Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 02 Jul 2022 Location: Hastings 4 now Status: Offline Posts: 2360	Post Options Post Reply Quote kruzaroad Report Post Thanks(0) Quote Reply 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.

JasonEdward Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 21 Sep 2024 Location: Waihi Status: Offline Posts: 125	Post Options Post Reply Quote JasonEdward Report Post Thanks(0) Quote Reply 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.

BC_Clark Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 15 Feb 2024 Location: Auckland Status: Offline Posts: 7	Post Options Post Reply Quote BC_Clark Report Post Thanks(0) Quote Reply 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.

BC_Clark Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 15 Feb 2024 Location: Auckland Status: Offline Posts: 7	Post Options Post Reply Quote BC_Clark Report Post Thanks(0) Quote Reply 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.