Micrometer Frames

[Downwindtracker2]

I just bought a 100-125mm Mitutoyo mic, standard C-frame with holes. Putting in the drawer I looked at my 75-100mm a Bestool-Kanon. Instead of the C-frame you would expect for a 4" mic, it was a heavier but bit shallower U-frame. I wonder why, were they special for something? Or did they copy someone else? Kanon is Japanese. The thimble and ratchet were very much nicer to use than Mits and Starretts. I had picked it up about thirty years ago at a machine shop supplier on sale.

[TomG]

Are you sure they are shallower? A lot of micrometers, my Etalon's for instance, use the U shaped frame design for strength. Don't forget, the useful depth occurs coplanar with the anvil.

Tom

[Downwindtracker2]

You are right ,Tom. I then climbed up and got the box that has the 0-6" VIS mics are in and checked this time, the 4" instead of the 5". Exactly the same. I guess they both copied Etalon. I think I should put that box somewhere easier to get at. I like the friction thimbles of the VIS, now that I have cleaned and calibrated them. They were a royal pain, that's likely why I found the set for $125 at a pawn shop .