Tricks for Centering on a rotary table?

[Sean S]

So, you can use an indicator on the center hole of the table to center the table, but then do you mount your work on the table and center that in relation to the spindle, or is there a way to center reference to the (already centered) rotary table itself?
Are there tricks to speed up this process (like using a live/dead center in the spindle to position the table, etc?).

Going for the FAQ hall of fame.
Sean

 

[Pat McGuirk]

Hi Sean,
For the rotory table I used at work, someone had made a plug for the center hole of the r. table. The plug had a ¼" dowel pressed into the center of it to mate with a ¼" slip fit hole in the part, if it is possible to have one there. This will quickly center the part to the r. table.
On your question about using something in the spindle to center up to the r. table, that should work just fine. I don't think you would notice a difference in the end product, unless you were quite a ways off, and wouldn't show up at all in some cases, depends on the job.
Take Care,
Pat

 

[carla @ tactical link]

hi, sean,

yes, you can sweep the centre hole in the rotary table with an indicator held in the spindle, and get the table centred with the spindle.......

then, to centre the workpiece itself, you first decide what accuracy level of centring you need.....just using a pointy mill wiggler in the spindle and aligning it with scribed lines on the workpiece can get you within .005 if you're careful.

if you need to be closer, take a step back in history....."button up" the job with a toolmakers button......drill and tap for the button in the workpiece's approx centre, snug up the button, adjust the button to the exact desired relationship with whatever surface or other feature of the workpiece defines your centre, and tighten up the button.

when your workpiece is placed on the rotary table, sweep the button with an indicator in the spindle, adjust position til your indicator zeroes out, and you'll have it centred within the possible accuracy of the setup.

re-check after clamping, of course, and adjust as needed.

cheers

carla