How to true up 3 jaw chuck

OneIron

OneIron

On the snap, Vinny!
Silver Member
I have a Hightower Deluxe lathe. When I chuck up a precision ground dowel, my dial micrometer shows about .004" runout. What's the best way to true it up? Or is this enough to even be concerned?

BTW, not a knock on the Hightower. I've been using this one for over 10 years and I'm completely satisfied. It's just that I have no prior experience with lathes and I want to be as accurate as possible.
 
There are several ways to true up a soft jaw scroll chuck. You can bore the jaws or you can shim the work piece. By nature a scroll chuck will be truest at one position and the amount of runout will vary with the diameter of the work piece. .004 T.I.R. is a little more than I like but it is also easy to get a incorrect reading. Even the slightest piece of foreign material on the chuck will through it off. I would recommend that you just contact Mr Hightower. I am sure he would be happy to walk you through the process that he recommends.
 
OneIron said:
I have a Hightower Deluxe lathe. When I chuck up a precision ground dowel, my dial micrometer shows about .004" runout. What's the best way to true it up? Or is this enough to even be concerned?

BTW, not a knock on the Hightower. I've been using this one for over 10 years and I'm completely satisfied. It's just that I have no prior experience with lathes and I want to be as accurate as possible.
Click to expand...

Ten years and only out .004" is pretty good if you have not trued your jaws up. But most likely you can get it truer.
Drop me an email at cueman@cuesmith.com and ask for "three jaw chuck repair instructions" and I will send you instructions on truing the jaws.
 
cueman said:
Ten years and only out .004" is pretty good if you have not trued your jaws up. But most likely you can get it truer.
Drop me an email at cueman@cuesmith.com and ask for "three jaw chuck repair instructions" and I will send you instructions on truing the jaws.
Click to expand...

I am sure that Chris will fix you up.

I have a few personal observations on that chuck. I have a Deluxe also and I have taken my chucks off the headstock and cleaned them. Remove them by unscrewing them and close the jaws all the way with nothing in them. Don't tighten them tight, just close them. Remove the back by taking out the big snap ring. Clean everything and lube it with white lithium grease. Make sure the jaws do not change position. Remove any burrs on the scroll with a fine file, especially on the ends. Put it back together and reinstall it.

Determine if it's time to replace the aluminum jaws. They are available. Grip a steel washer in the back of the jaws on the steel part, not the aluminum. Spinning about 1000 rpm, and using a small boring bar, take a few thousands off the inside of the jaws until they are clean.

What ever opening the jaws have when you bore them will be the most accurate position.

This is what I experienced...... My spur driver wobbled terribly. I fought it for almost a year until I found that the clamping accuracy of the jaws was most accurate when using one specific hole for the tommy bar. I numbered the holes and repeatedly clamped and unclamped the spur driver, checking each time with a dial indicator. TIR is usually 1 or 2 thou.

It runs almost dead nuts with hole #3.

Go figure. It works for me.

Kim
 
cueman said:
Ten years and only out .004" is pretty good if you have not trued your jaws up. But most likely you can get it truer.
Drop me an email at cueman@cuesmith.com and ask for "three jaw chuck repair instructions" and I will send you instructions on truing the jaws.
Click to expand...

Appreciate that, Chris. I'll do that.
 
tsp&b said:
There are several ways to true up a soft jaw scroll chuck. You can bore the jaws or you can shim the work piece. By nature a scroll chuck will be truest at one position and the amount of runout will vary with the diameter of the work piece. .004 T.I.R. is a little more than I like but it is also easy to get a incorrect reading. Even the slightest piece of foreign material on the chuck will through it off. I would recommend that you just contact Mr Hightower. I am sure he would be happy to walk you through the process that he recommends.
Click to expand...

I've found that I can get it pretty accurate by turning the jaws 1/3 of a turn until it spins true. But it's definitely time for a good cleaning. That's next.
 
whammo57 said:
I am sure that Chris will fix you up.

I have a few personal observations on that chuck. I have a Deluxe also and I have taken my chucks off the headstock and cleaned them. Remove them by unscrewing them and close the jaws all the way with nothing in them. Don't tighten them tight, just close them. Remove the back by taking out the big snap ring. Clean everything and lube it with white lithium grease. Make sure the jaws do not change position. Remove any burrs on the scroll with a fine file, especially on the ends. Put it back together and reinstall it.

Determine if it's time to replace the aluminum jaws. They are available. Grip a steel washer in the back of the jaws on the steel part, not the aluminum. Spinning about 1000 rpm, and using a small boring bar, take a few thousands off the inside of the jaws until they are clean.

What ever opening the jaws have when you bore them will be the most accurate position.

This is what I experienced...... My spur driver wobbled terribly. I fought it for almost a year until I found that the clamping accuracy of the jaws was most accurate when using one specific hole for the tommy bar. I numbered the holes and repeatedly clamped and unclamped the spur driver, checking each time with a dial indicator. TIR is usually 1 or 2 thou.

It runs almost dead nuts with hole #3.

Go figure. It works for me.

Kim
Click to expand...

Appreciate the response, Kim. Just when I think I know something pretty well, you guys blow me away. :cool:
 
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