Checking Runout on a Keyless Chuck?

Splat

Splat

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So I won a supposedly new-old stock Rohm keyless 1/32"-1/2" chuck that requires a 5/8" threaded arbor. This will be used (hopefully) on my first-ever lathe, a Heavy 10, once it's fully restored. I'd like to check the runout of the chuck but not sure how to go about it. I just bought an SPI brand 5/8-16" to MT2 arbor to use with the chuck. I do have a working mill with MT2 spindle so I'm thinking inserting the arbor alone into the spindle and then testing various points along the arbor with my DTI while rotating the spindle by hand. Once I know the runout of the arbor I can insert it into the chuck to test the chuck runout, no? How would I do that? Am I going about this the right way? Thanks.
 
To check the run out of the chuck, insert a steel dowel pin or piece of ground stock in the chuck and check the run out with your indicator right up at the jaws and at about 1" down on the pin. That should tell you if it runnings out and chucking straight.
 
Hmm...that's it? I can do that. :p I thought it couldn't be that simple, could it? I'll check it tomorrow. Thanks OldMachinist.
 
It's probably worth checking the inside of the taper before slamming the arbor home. Any little chip or dirt in there will amplify the runout you see at the pin. Does this arbor have a short ground shoulder that fits into a mating counterbore in the chuck? If so, I'd be curious enough to put the arbor in and check that shoulder before I mounted the chuck. Might help locate any runout you may have,
 
I would tend to agree with what Tony has said. The arbour could be a source for runout. It is worth checking it over, and indicating it to see if this runs true first.

I have purchased a few drill chuck arbours, offshore elcheapo brands, and found the arbour s to be the big problem.
 
Definitely check the taper FIRST. But, don't panic if it's off... It could be one of a few things some serious some not:

1) Whatever you're chucking the indicator's arbor in. You can indicate the shaft of the DTI with another DTI.
2) Tailstock too far fore or aft (just adjust it).
3) Tailstock too low or too high (you're kinda stuck with this without major surgery).
4) Bollixed up taper (this can be fixed, but requires a special reamer).

Once you know what you've got, then check the runout. Can you insert the taper into your headstock? Then all you've got to do is chuck up a gauge pin (or a good end mill if you haven't got any), and measure the runout directly.

John
 
Thanks guys. I'll use an endmill and install the whole shebang into the mill to test. First things first though I've gotta go help a friend and his family. They lost almost everything in that big apartment/condo complex fire two days ago. Kinda puts things in perspective, I gotta say.
 
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