Thanks. Ok that's a good design. So both designs (nuts or shims) must work well. I always thought a nut might move over time. Looks like Bob uses a lock washer on the top and probably bottoms out at the bottom with the additional bottom nut providing lateral movement support.
I know this mod isn't the most important but I figured it would be a little more doable than making some other internals. Last night I broke my groove cutter holder. Now it's broken, I hate to part with it. I have one on order but it will take a couple weeks. Then I'll be grooving again. I have a non-carbide, HSS cutter but that doesn't work well on this. Maybe I can use the HSS for the FT valve, which I still need to do. When cutting and facing, should I
the valve half with tape to prevent damage in the lathe chuck? Or what is recommended?
For the piston, I do need to check if there is enough diameter at the threaded area (minor) to even cut a crotch (forgot that key part). If not I'll just turn it down and take this advice and thread it. I got some more very large screws (cheap) today 5/8" diameter that would be easier to do a one piece cause I could put the oring groove anywhere on the shoulder. Still a lot of work and stupid time-consuming work at that. Don't worry you can tell me that. I can take constructive criticism.