Need Help!- How to center a part on a rotary table

[ryansuperbee]

Hey guys, I know this must be an elementry question. But it's something I don't have too much experience in. I have an 8 inch CNC rotary table ( call it manual if you would like, same thing) I usally have it on it's side to perform the cuts necessary for me to get the job done. I can get the work piece close to center, but then I have an issue of securing it to the rotary table. I'm trying to think of a faster and more precise way to center and secure my work. Is there any way that I can attach a lathe chuck somehow to the fourth axis? I would think that would slove the issues I'm having. If you have any ideas or if you know how to attach a lathe chuck to a fourth axis please let me know!!! Thank you.

[Geof]

Your rotary table must have tee slots; probably six.

Find a lathe chuck that bolts on from the front; nearly all the Bison chucks do with three bolts.

Buy an eight inch Bison chuck and bolt it to the rotary table.

[acondit]

Ryan,

If the chuck is smaller than the rotary table, then:
Machine a flat piece roughly the size of the rotary table.
Drill holes to mount it to the rotary table.
Figure out how to get it back into the same position after removal.
( Could be 4 pieces the width of the T-slots screwed to the back surface (as a cross), a couple of alignment pins bored into the table surface, or center hole and center taper to match tables center taper hole).
Mount the piece to the rotary table.
Then use the rotary table to turn down the outer portion of the piece leaving a raised circular portion the correct diameter to serve as a register for the chuck.
Then drill mounting holes for mounting the chuck. These holes should be recessed on the back side for cap head screws of the correct size.

Alan

[digits]

I would strongly suggest using a 4-jaw chuck - they are more accurate than 3-jaws and you don't need to worry about centering them on the table all that precisely. I made an adaptor for mine using a very similar method to the one described by acondit. Here's a couple of links to me making and using it:

There are some pics about half way down here...
http://www.cnczone.com/forums/showthread.php?t=34954

And it's in action here.
http://www.cnczone.com/forums/showpo...6&postcount=43

Though, that is with my 3-jaw mounted - I think I centred that by lostening the T-nuts and then indicating off a smooth portion of the chuck body and bumping it into place.