Subject: Rotary Table Question

From: Roger M Weppelman <[email-masked]>
Date: 1 Jul 1996 14:36:42 GMT

When using a rotary table on a milling machine, the first step is mounting the 
workpiece so that the center of the arc to be cut or the circle to be inletted is 
located at the table's axis of rotation. What's the easiest way of doing this?

Up to this point, I have been centering the rotary table to the milling machine 
spindle with an indicator, locking the table, and then placing the work piece on the 
table and centering it to the spindle with a wiggler. But there has be be a better 
way. In particular, is there any way of directly centering the work piece to the 
table's axis of rotation without centering both to the spindle?  All suggestions 
appreciated.

Roger Weppelman

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From: [email-masked] (Jonathan M. Elson)
Date: 5 Jul 1996 06:03:01 GMT

Roger M Weppelman ([email-masked]) wrote:
: When using a rotary table on a milling machine, the first step is mounting the 
: workpiece so that the center of the arc to be cut or the circle to be inletted is 
: located at the table's axis of rotation. What's the easiest way of doing this?

: Up to this point, I have been centering the rotary table to the milling machine 
: spindle with an indicator, locking the table, and then placing the work piece on the 
: table and centering it to the spindle with a wiggler. But there has be be a better 
: way. In particular, is there any way of directly centering the work piece to the 
: table's axis of rotation without centering both to the spindle?  All suggestions 
: appreciated.

I could think of some sort of fixture to do this, but no procedure, unless
you do some modifications to the table.  One possibility is to cut the OD
of the table down a few thousandths until it is absolutely concentric to
the center of rotation.  Then, you could move a workpiece around until a
caliper reads the same from the edge of the piece to the edge of the table
at three or four points around the table.  Then clamp the workpiece.

You could build a fixture that clamps over the table, and has a centering
hole at the exact center.  Place work (perhaps with a punch mark at the
point to be centered) on the table, then lower the fixture onto the table,
over the work.  Pass a transfer punch through the hole in fixture, and
move work until point on punch enters punch mark on work.  Clamp work,
remove fixture, voila!

If you plan to do a lot of this work, then this may make sense.  I don't
use the rotary table much, but it is very useful when needed.  The
multiple alignment process is cumbersome, but a few times a year, I don't
worry about it.