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+--- Thread: [HELP] Centering on a rotary table (/thread-2484.html)
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Centering on a rotary table - Dan Boy - 01-29-2015
Hi guys, as the title suggests, I want to be able to center a part on my rotary table to mill a groove for an o-ring. There must be a way, an easy way to center the part. I just can't think how I am going to do it.
I had thought I could use a DTI on the center of the part but positioning the part accurately will be difficult.
Any thoughts?
Cheers, Dan.
RE: Centering on a rotary table - DaveH - 01-29-2015
Make a disc to fit the inside cut out put a little hole in the centre of the disc and align that up
DaveH
RE: Centering on a rotary table - Highpower - 01-29-2015
(01-29-2015, 01:55 PM)Dan Boy Wrote: I had thought I could use a DTI on the center of the part but positioning the part accurately will be difficult.
Cheers, Dan.
Sweep the ID of the part with your DTI and adjust the x-y position of the table until you get an equal reading all the way round the part.
https://archive.org/details/VerticalMill_IndicatingCenterofaHole
Or use an edge finder to locate two opposite points and split the difference on both planes (x & y). You'll have to use the machine dials to measure across the opposing edges - with some special attention.
Or, just use Dave's suggestion and be done with it.
Another option would be to use a co-axial indicator in the machine spindle and just dial the table into zero with the handles. Bottom line is to use whatever method that is available to you, as long as it works for you.
RE: Centering on a rotary table - f350ca - 01-29-2015
Dan for an O ring grove would the 3 jaw on the lathe not put it close enough to centre? A lot quicker and a cheaper cutter.
RE: Centering on a rotary table - PixMan - 01-29-2015
On my rotary table there's a Ø 1.000" bore at the center. I made a plug that fit into that to near it's bottom. A shoulder on the turned plug was made to fit the mating part that I wanted centered on the rotary table. Done, slip the plug into the bore, tram with a dial test indicator to know where X-Y zero is set, slip the part to be machined over it and go.
RE: Centering on a rotary table - Dan Boy - 01-30-2015
Sorry if I'm missing something here. I can center the rotary table to the mill, thats not the problem, the problem is that I need to center the part on the rotary table to mill the groove.
The part is too small to get it in or on my lathe chuck also.
Cheers, Dan.
RE: Centering on a rotary table - Dan Boy - 01-30-2015
I think PixMan, I understand what you are saying there. Make a disc up to fit the part over. Centering the disc wouldn't be so hard I guess.
Cheers, Dan.
RE: Centering on a rotary table - Shawn - 01-30-2015
If you cut the disk on your lathe, use a centre drill to indicate the centre of the disk and then use a centre finder on your mill to indicate the part and the disk.
![[Image: 250.1240.jpg]](http://littlemachineshop.com/products/Images/250/250.1240.jpg)
RE: Centering on a rotary table - RobWilson - 01-30-2015
The same way you would clock the job in if it was to machined on a lathe face plate .
Rob
RE: Centering on a rotary table - TomG - 01-30-2015
Dan,
The quickest way for doing a number of parts is to make a plug that will fit snugly to the inside diameter of the parts, with a shaft on it that can be held in a collet or drill chuck in the mill. Then you just center the table with an indicator or edge finder and use your plug thingy to center the parts on the table.
Another way to fudge it with a symmetrical part is to use a pin of known diameter chucked in the mill. If you calculate how far the inner edge of the bore needs to be from center, you can drag the part out that distance on first one axis and then the other. Be sure to double check your work after the part is clamped.
Tom