Milling Cutter Holders for Unimat

[Paul Jones]

Melkal and Captain,

Thank you for the compliments.

The Unimat milling cutter holders was one of my early "must have" tool additions before I totally tricked-out my old Unimat SL 1000 that I bought new in 1970 (please see http://www.homemadetools.net/forum/m...00-lathe-10111 for the continuing saga on my Unimat improvements).

You want to preserve the quality and accuracy of the hardened jaws of your 3-Jaw chuck and best not to hold the HSS or carbide milling cutters in the 3-Jaw chuck. Plus you can never have a really tight grip on the milling cutters and may have them "pulled" from the chuck destroying the part and other things (early-on this happened to me).

There is a way to restore the parallel alignment and TIR (Total Indicated Reading) of your Unimat 3-Jaw chuck to better than new. I have preformed this with a Dremel tool with 0.375" diameter Aluminum Oxide Grinding Stone and the Dremel tool mounted in a special holder held in the Unimat tool post. Most important in this operation is to "pre-load" the chuck jaws to take the slack out of chuck jaws for holding on the inside surfaces of the jaws and ensuring the chuck jaws will be ground concentrically. Also grind less than 0.001" per multiple passes before taking another grind on the jaws. There is no rush because you only have to do this every 10 years or more. There are many articles and fixture designs on the Internet for doing lathe chuck grinding. It is much easier with the Unimat because the homemade chuck pre-loading fixtures are so small that these can be made from 1/8" aluminum plate and drilled-out with a drill press and no need for a milling machine.

Good luck on your Unimat endeavors,

Paul Jones