Rotary tabel and 4 jaw chuck

R

rzw0wr

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I set up my rotary table to the 2mt hole in the middle. I am using a coaxes indicator.
I moved the table until all sides read zero.
I then rotated the table around to make sure it was in center. It was on the money.

I mounted my 4 jaw back plate that registerd on the 2 mt pin in the middle of the table.

Mounted the chuck registered and ran the table around check center. Looked great.

I mounted the 4 jaw chuck, Put a piece or round stock I had just turned on my lathe.

I set the bar of stock as I had for the table.
I turned the spindle around the stock, move the jaws until all sides showed zero.

I rotate the table and it shows the stock out over .010 thousandths.

Am I setting the stock wrong in the chuck?
Should I do it like a lathe, rotating the table?

Thank you,
Dale
 
The rotary table AND stock must read 0 .
 
Can do some tests to try & figure out where the error is.

After you use your coax indicator at the MT hole to center the RT. Use a regular indicator to see if there's a discrepancy.

Next check if your chuck backplate is flat (parallel on both sides). You can do this by measuring the thickness all the way around the backplate. Or mount the backplate on the table, put an indicator on it (more importantly near where the chuck would sit on it) & rotate the RT table to see if you get runout.

Then there's checking the jaws on your chuck to see if they are square. Just mentioning as I have no idea if it's a used chuck, new, etc.
 
The table is zero.

darkzero, I rotated the table around the mt pin. It came out zero. That should show the table being centered, correct.
The chuck is new from Shars.
I will check the back plate. I made it.
 
I'm leaning towards the backplate as the culprit. Happened to me on one of the backplates I made for my RT.
 
Yeah that wouldn't cause it to be 10 thou out. Could have just been shop gnomes messing with you. Try setting it up again. This time try centering the part in the 4 jaw by rotating the RT table instead of the spindle. Really it shouldn't matter much if you rotate the spindle with an indicator in it unless your tram is out.
 
Who cares? Its a 4 jaw. clamp the part, rotate the table and adjust the jaws on the chuck until the stock runs true.
 
Well.... I will have to wait until next week.
I just dropped my coaxial indicator on my concrete floor.
No working. Used Blake CX is on order.

Thanks for the help,
Dale
 
You don't need a co-ax to indicate any of that. A co-ax indicator is just a convenience. Some people don't even like them or own one.
 
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