Very good info!

Didn't mean to intrude usually I just listen.
Thanks,
Robert

I agree Graham. I just didn't know what would be acceptable on my mill. I know, what kinda tolerance do you want to hold. I don't know yet. I do know that the max diam. would be 12" or less.

Thanks Chip,
   Looking for you to school me.

You will find its not the step accuracy thats the problem,  it will be the backlash,  the worms in the less expensive tables are not made to the kind of tolerance the electronics can control.

Even if you adjusted the unit you would have tight and light spots in places.

Lash on large dias is a big problem,  locking the table unless its made for it is even harder.

Graham.

I have built and installed a 4th axis on my machine.  I have seen several posts regarding this but have not discovered a solution to my problem. 
 My "A" axis is set to 22.222 steps per, 10002 as the velocity and 1700 as the acceleration.

The problem is that when you are doing a move that uses one of the linear axis, say the "Y", and the "A", the feed rate may be 35 ipm or similar.  It takes forever for the rotary axis to move to the desired position based on that feedrate.  How do you deal with this big difference?

Can someone help me out?