Non concentric diameters on part

[P. Waller]

This is how I make a lathe part with non concentric diameters, this is not the only way or the textbook "correct" method, however it works for me so I do it.
Turn the first diameters in over sized stock, in this case 11/4" 304 SS bar.


Put an indicator in the toolpost and set it as if it were a tool, if you have a DRO just give it a tool number, set it to a known diameter using the revolution counter and set the bezel at .0, in this case it is a 2" travel indicator so I set it at .5 and .0 on the dial. If the indicator is off center by a few thousands of an inch it will result in the offset being a few tenths off at another diameter, in this case the offset is .177" +-.005 so this was not a problem.


Flip the part in a 4 Jaw chuck and use the indicator to set the offset, the difference is .354 on the diameter. When the indicator reaches .354 difference you are good to go so have at it.

It looks like so when finished, it has a .059" retaining ring groove on the small end as well, this is not Rocket Surgery just simple lathe work.

 

[benmychree]

I used to have to do that frequently with one of the products that I used to make, I took a chuck backplate without a register and pivoted the attachment bolt on one side and cut a slot in the other side of the mounting plate for the chuck, so the chuck could swing off center, and I cut graduations at the interface of the two parts to indicate the amount of eccentricity; this worked well, but of course could not be run fast due to the out of balance.