Valve mod - pcp pistol |
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Pauly5
Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1348 |
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Well I tried cutting one of my donor screw drivers and it was hard. The hacksaw had trouble biting into it. It made a small nick, so I just put it in the vice and it snapped on the nick.
Doing pest control I was always up in ceilings and sparkies often forget stuff and they do like to have expensive screwdrivers which are decenyly hardened. So I have a couple I can wreck. So this will be my valve stem. |
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RangerPete
Senior Member Joined: 18 Apr 2023 Location: Cambridge. Status: Offline Posts: 794 |
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Good luck with that 😂
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Walk quietly, but carry a big stick.
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Pauly5
Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1348 |
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Slowly doing stuff.
NZ Post has botched up Nunga's foundry delivery, so valve on hold. I bought a piece of 3.9 mm piano wire today. Pretty hard, and hopefully harden up, but I might try that for the valve stem. I also decided to use the .25 cal FX barrel I had. It was off a Bobcat. I cut it down and reduced the breech end to fit into what will be the breech block for this build. Fits nice and snug with no movement. FX only rifled the last 2 or 3 inches of these barrels and you can see that they make the muzzle smaller diameter to do this, then thread on a piece to match. You can see the marks on the outside where they "squeeze" the rifling in giving it a "smooth" twist. |
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RangerPete
Senior Member Joined: 18 Apr 2023 Location: Cambridge. Status: Offline Posts: 794 |
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So how long are you planning on making the barrel?
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Walk quietly, but carry a big stick.
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Pauly5
Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1348 |
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Barrel is around 300 mm, so not a small pistol.
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J-S
Senior Member Joined: 19 Oct 2014 Location: Auckland Status: Offline Posts: 395 |
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very cool
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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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Pauly5
Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1348 |
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So i found a piece of brass to use. I have made the poppet valve and loctited it to the stem.
After it was fastened I finished off the seat and polished it so the it was concentric with the shaft. I am quite pleased with how it turned out, but of course being pretty doesn't mean it works. I also polished the valve seat. I have some of the 3M polishing cloths, 800 up to 15000 grit. It is satisfying working through them and seeing the finish improve. |
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nunga
Forum Moderator Joined: 08 Mar 2013 Location: Pukekohe Status: Offline Posts: 970 |
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Silly question, You are going to lap the seat in right? That brass looks nice but is it just the picture or are there a lot of machine marks still on the face of that? hope it seals. Nice work! I will get the other brass sent out again for you anyway and you can use it on another project if you dont need it for this now.
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2nd place HP springer - WFTF World Championships 2014
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KiwiTR6
Senior Member Joined: 03 Nov 2022 Location: Stratford Status: Offline Posts: 264 |
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Paul, I've found Solvol Autosol to be excellent for final polishing. I'm not sure if it would be coarse enough to finalise the metal to metal seal though. I have heard of people using moistened cigarette ash on fuel needle jets, but that's probably finer again.
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FX Wildcat MK111 BT Sniper .25
FX Dreamline Classic .22 Diana Outlaw .22 Cometa Fenix 400 .177 Weihrauch HW50 .177 Air Chief Junior .177 ($100 Challenge) |
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Pauly5
Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1348 |
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Thanks guys, yes I was going to use something to bed the two together. I have Autosol, valve grinding compound and even toothpaste.
Nunga, this is kind of a test run. I don't know how well this will work and so the good thing is that I can take the whole valve system out and replace it, so I will use your piece of brass because it was made for it. It means something to me to use the piece cast especially for it. I can make the mistakes on this first one.
The other thing I was going to do was make the seat out of delrin. |
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