Chuck thread/spindle thread repair

jwmay

jwmay

H-M Supporter - Gold Member
H-M Supporter Gold Member
I’ve tried several combinations of keywords, but haven’t come up with anything yet. So I figure I’ll just ask.

Has anyone here ever repaired the spindle threads on their lathe? If so, how?

Next question: has anyone here ever repaired the threaded ID of a screw on chuck? If so, how?

I’ve got one of each, and am not terribly concerned about keeping/using either component. But, if it can be done, I’ll try it.

I’m thinking 4 jaw chuck, extreme persistence in dialing in the part, and then pick up the threads...somehow...and make very light passes until I find what’s holding me up, then several test fits with a pre made threaded arbor for the chuck, and then use the chuck for test fits on the spindle after the chuck will screw on to the premade, known correct threaded arbor.

I suspect there may be a compatibility issue that needs to be verified, or proven a false suspicion before I do anything else. It’s possible the chuck wasn’t even meant to go on this spindle and somebody managed to ruin both while trying to MAKE it fit. It wasn’t me. I promise.
 
How about thread files , or just a 60 degree file ? Cleanup your spindle threads and then the chucks . If the chuck wasn't meant to fit the spindle ....................it won't ! :grin: If it was , pick up the internal threads and re-chase them to clean them up also ..
 
Dykem can be a big help to determine where the interference lies. Once you find out where the binding is, you are well on
your way to making it fit. Are these standard threads or acme threads? It takes only a very small amount of misfit to cause
problems. A small file or riffle file is very helpful to remove small amounts of metal in strategic places.
 
cathead said:
Are these standard threads or acme threads?
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Standard threads. The chuck was included with a lathe basket case I recently bought. The PO told me there was something wrong with it, and that it wouldn’t screw on all the way.

Anyhow, I tried it on a different but same spindle and it wouldn’t even start. So then I tried a good chuck on the recently purchased spindle and it wouldn’t thread on either. After a couple more investigative swaps, I was convinced both chuck and spindle are damaged.

Thank you to both of you. I will use all of your suggestions. I don’t have any thread files yet, so it may be a bit. But I can test fit with dykem , and use a regular triangle file, and some riffler types if I can.

Thanks again!
 
What is the make and model of lathe? Some lathes have a strange spindle thread. Grizzly's G4000 has a metric spindle thread. My G0602 has a 1-3/4" 8 thread which isn't a common size.

Before attempting any type of cleanup or repair, I would measure the threads on both the spindle and the chuck. Major diameter, pitch diameter and pitch on the spindle. The minor diameter and pitch on the chuck/back plate.
 
RJSakowski said:
What is the make and model of lathe?
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It’s an Atlas 10F lathe, Model V36. The chuck is a Westcott model 6905. My thread gauge only goes to 13 for coarse threads. I’m guessing I can make some reasonably accurate guesses based on caliper measurements, and counting?
 
Use a ruler and count the number of threads in 1/2”. 4 is the number you are looking for. Not 3 which is before 4 and not 5 which comes after 4! Monty Python and the Holy Grail.
 
The shop I worked in had a 11 x 24 Summit lathe with a 38 x 3 metric threaded spindle. That's 1.496 x .118 in inches. It fooled us for a few minutes when we had to make a backplate for a collet chuck to fit. At least we figured it out before we started cutting metal. Could the backplate be cut for this thread?
 
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