Do I Need To Resurface The Back Of My Chuck

[Swerdk]

regarding test indicator
1 div= .0005

I set the test indicator zero, this is the worst I get when I tested the spindle portion of chuck 00020

( 4 divisions)that is supposed to say twenty ten thousandth.

◦ did I read that right?

◦ My three jaw Chuck on the other hand is off by 14 divisions with a .0005 test indicator.

does that mean I need to clean up back of 3 jaw?


◦ Does it really matter? that is the question
I don't need more work but if it's going to skew my work I will do it.
◦ math question is .0005 x 14 divisions = 0.007 ?




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[Andre]

In the first picture, if that's how you took your measurement you need to re-measure it. When you are using a test indicator the needle has to be as parallel to the surface as possible, not perpendicular. Or you get a false reading. Some pics for reference (not mine).

http://i.ytimg.com/vi/jz9dWUUxibE/hqdefault.jpg

http://itdc.lbcc.edu/oer/machineTool/precisionTools/precisionToolsALT/images/dial2.jpg

My three jaw Chuck is off by 14 divisions with a .0005 test indicator.

14 divisions of a half thousandths indicator (supposing every division is a half thou) means the chuck is off by .007". Acceptable for most 3 jaw work.

How many .001 = .0005

.0005" is half of .001".

 

[Swerdk]

Your to quick i just cleaned up post. I did not know that about test indicator placement though


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[Swerdk]

I will remeasure


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[John Hasler]

Looks like you are measuring the face of your spindle, not the back of the chuck. Is that a registration surface? If not it doean't matter.

Andre is right about the technique.

 

[Swerdk]

I measured the face of my spindle then the face of the chuck to see the difference. I figure if there is a difference then it must be the back of the chuck causing it?


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[Swerdk]

I wish i could work in garage as much as i am chained to a county desk for another 10 years


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[eeler1]

Check chuck runout. Mark your posts and locks where the least runout occurs. Always mount it in the same location.

If you still have a problem, then start looking at other suspects.

 

[John Hasler]

Install the chuck on the lathe and measure the axial runout on the face of the chuck. Then chuck up a piece of precision rod (1" or so) and measure the radial runout of the rod near the chuck. Those are the numbers that matter.

 

[Swerdk]

Axial runout? Thats the face of the chuck correct?


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