mikeehlert wrote:
Pictures: I wanted to post a picture at day one but the part is proprietary and just discussion on the forum is causing some angst.
Understood. Some times a guy simply can't tip his hand.
I have considered a couple other methods of performing the operation in the hopes of balancing things. Mounting a tool post grinder on the lathe and switching to a milling operation with a many toothed cutter. Any thoughts about those approaches?
Yep!
I'd be inclined to lose the multiple tooth idea, as each tooth lends to the problem. I'd likely endorse the tool post grinder idea, though (in spite of the fact that it is, in theory, a multiple tooth approach). Working as a tool maker, I often had an unusual requirement to fulfill, including shaping foam rubber. I still have a spare of one piece I had to make (made two in case one was scrapped during the process). I mounted a small air grinder in my tool post and ground a cavity in sponge rubber. Worked extremely well, and would have been impossible by turning.
If you use a coarse, hand dressed wheel (hand dressing is very important in this instance), that should present the lowest possible cutting pressure, and it has the potential to yield a great surface, although that's up to the operator.
In the mean time, I am getting materials for testing vacuum and/or double sticky tape.
I certainly endorse that approach. It's often difficult to determine which process will work best, so, especially if then job will repeat, or there's a large number of pieces involved, experimenting is likely the best approach. Tough jobs often resolve themselves that way.
By the way, discounting tape can be a mistake. I recall an instance of tape being the only solution to an ongoing problem, which I'll relate.
I started in the trade back in '57, at Sperry Utah Engineering Laboratories. We were involved in the R&D stage of the Sergeant Guided Missile, which was a ballistic missile. Strange is it may sound, it had brakes, which were used to control the destiny of the missile, and that's the interesting part of this story.
As a part of the brake assembly, a thin magnesium bridge casting had to be machined, and held to .005" flatness. Any fixturing that was tried resulting in minor distortion, making it impossible to hold the .005" flatness. In desperation, tape was tried, and it worked perfectly well, although it demanded extremely fine cuts. They learned to rough the parts, then go back for finish cuts. Problem solved.
Harold
