Thin Parts..Thin Shims..Drill Chuck Runs True..Fixing stuff that is not quite right

[jjr2001]

I found some Jacobs chucks at fire sale prices on eBay. Bought a few and a couple of MT-2 arbors for them. They are designed for threaded arbors so that is not the best way to get a true running chuck but work ok for portable tools.

The challenge was to get the assembly of arbor to chuck to run true..Maybe not perfect but better than the .013" inch that I had when the parts were mated.

There was this video by Joe Pieczynski (one of my favorite machinists) on YouTube so I used what I learned there to make some .001, .002, .003 and .005 shims out of my sheets of shim stock. I ended up with two nice arbors with washers that can be used at a later date for some other project and a bunch of shims with 3/8" and 1/2" center holes and they were easy to make using Joe's method with a bit of modification. Joe used the tail stock to hold the bunch of pieces together on the lathe but I made the two small mandrels out of some bolts and nuts. Just cut out a bunch of square pieces of shim stock. Clamp them with two scrap squares of aluminum about 3/16 thick. Drill the bunch in the center for your arbor diameter. Make an arbor from a common shop bolt of the proper diameter. Clamp with nut and turn in the lathe until they have the outer diameter you need.

Joe Pieczynski

By adding shims and testing the runout with a 1/4" dowel pin in the chucks I was able to get them to run better than .002" run out. Not bad for some $12.00 chucks.

Chucks are still available here: Jacobs 5038C 33BA 5/8-16 Thread Mount 2-13mm Cap Plain Bearing Chuck

They also have 1/4" and 1/2" inch Jacobs chucks.

I bought the chuck keys from McMaster Carr.