Author Topic: How do I get this chuck centred?  (Read 4021 times)

Offline John Hill

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How do I get this chuck centred?
« on: March 19, 2011, 05:27:19 AM »
OK, I got a new mill, rotary table, dividing head and of course I've still got my lathe.

The dividing head has 1 1/2"  8tpi mount so taking the lead from Bogstandard that will be my 'standard' for mounting on multi machines.  I have a small (unmounted) chuck and a threaded face plate for the dividing head.

I made a taper to fit the rotary table with a thread for the plate and it mounts nicely, I made a 5 morse taper with a thread for the lathe and the plate mounts nicely on there. 

But how do I accurately position the rotary table with the plate to drill the holes to mount the chuck?
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Offline Bogstandard

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Re: How do I get this chuck centred?
« Reply #1 on: March 19, 2011, 06:08:07 AM »
John,

As long as you have the plate centred up on the RT, there is no need to centre up the RT to the quill.

Just move the RT to a position where you want the holes to be in the plate, they usually give you the PCD with the chuck, if not, just measure the back of the chuck from the centre to the centre of the hole, mark up one hole centre on the plate and drill a hole, then making sure your plate doesn't move, if it is four holes, rotate it by 90 degs, and drill next hole, 120 degs if it is a 3 hole version.

That goes for anything you want to drill around a circle that is centred on the central position of the RT, whether two holes or twenty, as long as you have the first one marked on the job so that you can pick up on it, there is no need to centre up the RT. Drill the first, turn the correct amount of degrees, and everything will be spot on.


John

NB - make the holes in the plate say 1/2 mm larger, it is the accuracy of the backplate spigot that fits into the chuck that keeps it central, the bolts are only there to hold the chuck in place. By having the holes slightly larger, that ensures the bolts don't interfere with the chuck sitting on it's spigot correctly.
« Last Edit: March 19, 2011, 06:18:28 AM by bogstandard »
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Offline John Hill

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Re: How do I get this chuck centred?
« Reply #2 on: March 19, 2011, 03:52:23 PM »
Thanks John,  thats clear now, I must have been having a bit of brain fade. ::)

I will get onto that right after I finish my breakfast!
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