Rotary Table Alignment Question

[devils4ever]

I spent a lot of time aligning my RT to the spindle. I got it within a thou or so. That was the best I could do. Then, I added a fixture plate to the top of it and aligned that as well. So, I assume means the two are aligned to each other?

If I leave the fixture plate on the RT and move the mill's table, all I need to do is realign to the fixture plate in the future by moving the table. Is this correct?

 

[RJSakowski]

Assuming the RT remained fixed to the table, that would be correct.

 

[RJSakowski]

When I align my RT with the spindle axis, mount a piece of stock roughly over the axis of the RT and an end mill in the mill. I offset the RT from the mill spindle and rotate the RT to cut a cylindrical boss. The boss will be perfectly concentric with the RT axis. Then I mount an edge finder to find the center pf the boss and set my DRO to zero on that center. The mill spindle axis now perfectly registered with the RT axis. (Perfectly within a few tenths.)

I use this method because I usually have a 3 jaw chuck mounted on the RT so the central bore isn't accessible to using a test indicator and an Indicol. Also a round boss is often a feature of the part and this removes chuck runout from the mix so there is no extra work involved.

 

[devils4ever]

I used the Morse taper in the center of the RT to indicate off of. I have a chuck for the RT, but am using a 3/4" thick fixture plate to mount my part. That sounds like a good technique though.

 

[ChazzC]

I have a Sherline 4” RT l use on my Mini-Mill: it has a 0.4275” locating hole instead of MT center hole so I use a piece of 0.4375” drill rod for alignment. Use the same method to align ER collet chucks and my Flexi-Chuck. I use a smaller drill rod for centering if the 3-Jaw is on since it has central through hole that is smaller. Doesn’t get me as close as a DTI, but fine for most of my work.