Still working on my little problem with one of the 4 chucks I bought and their arbors.
None of them were true. Chucks run out and arbors run out except for one.
The R8 to 5/8-16 jacobs chuck worked right out of the box. The pair are better than .0015"
which is a number I can live with.
On the other hand the MT2 to 5/8-16 Jacobs chuck was running about .013"....Yuck......
So I stole the Buck Chuck method (sort of) and made a simple adapter on the lathe that
would allow aligning the chuck to the arbor better than .001"..
And yes it works great.
The housing is 1.750" for the OD
Single point the ID thread (5/8-16) in the housing while still in the lathe.
Bore out the housing to 1.250" diameter and .625" deep. This will
be the well for the adapter.
Drill 4 set screw holes in the housing (10-32) seemed like a good place to start.
These will be the adjustments and the holding force for the chuck adapter.
They must be positioned in relation to the V-groove so they push the adapter
to the rear of the housing.
Turn the 5/8-16 OD thread for the adapter on the lathe as well.
The adapter's OD should be about .020" smaller than the housing diameter
which makes it about 1.230".
The chuck adapter has a V-groove that pushes the adapter to the rear of the housing.
The front portion of the V-groove was removed for screw clearance.
The set screws points were ground with a tapered end. (not shown)
Now I need this just for center drilling on the lathe so the set screws will have
enough force to keep the adapter from spinning. If you need a lot of torque then
I would add at least 2 cap screws (counter bored) that would be installed from the
back of the housing and into the chuck adapter. These would be snugged up while
aligning the adapter and then tightened full after the alignment was completed.
My lathe has an MT-3 taper in the head stock so I used a MT3 to MT2 adapter
to hold my MT2 arbor while dialing it in.
One day project to make a true running chuck adapter.