I would bore all the parts first.
leave them oversize in width if you want.
Set them aside
Chuck a 3/8 socket head cap screw (Allen) on the threads and turn the head to a taper of about 10 to 30 degrees, so the head resembles a taper pin .
Flat heads have too blunt a tapper to use here
Now,make an expanding arbor.
Take a 1 1/4 piece of steel or aluminum.
center it and tap drill for a 3/8..tap it like 1 inch deep
Counterbore the hole to the middle of the tapered head diameter.
Remove the arbor and saw cut about 1 inch of of the end into 4 quadrants.
No accuracy is reuired.
Return it to the lathe ...DO NOT remove it till the whole job is finished!
now screw in the Cap Screw and wedge it into the c'bore till it expands the
arbor, and turn the diameter to exactly the size of the bores for about 1 inch.
Now when you loosen, the bores will mount and then tighten and you will have very accurate bushings that you can work on the sides and the OD. you will have no run out here, if you turned the fit with the screw tightened..
For llighter jobs, and out of balance jobs, some guys dispence with the screw and taped hole, and only centerdrill the hole and use the tailstock center for expansion.
You must be vary careful however that the tailstock does not loosen up.
it also does not provide the higher level of grip that a screw gives.
You may want to do a combination of both to get rock steady support.
Rich  |