- Joined
- May 3, 2017
- Messages
- 1,997
I have an Eissen 1440 lathe that I bought new a little less than two years ago. The machine has not been moved or bumped since initial setup. It's been a great machine, but I've noticed lately it's cutting a taper toward the tailstock end. It became apparent when I needed to turn a piece about a 10" long, using a live center in the tailstock. The taper was about ten thou over the full length. I checked bed alignment - nearly perfect but I tweaked it even further. The resulting change was negligible. I chucked up a piece of 3/4" aluminum and turned about 4" without the tailstock. Taper was still there - actually the relative taper was a little worse, given the shorter section. Next I took a piece of 1-1/4" O1 tool steel that is about 3 feet long and chucked it up with 10" showing through the chuck. I mic'ed the 10" section at various points, and it was uniformly dead-on 1-1/4" throughout - just like tool steel ought to be. Using a high precision indicator and rotating with the jog switch, I took measurements of runout at three positions (see photo below). Here are the results:
At 1-1/4" from chuck jaws - zero - +0.0044" TIR
At 4-1/2" from chuck jaws - zero - +0.0091" TIR
At 9-1/4" from chuck jaws - zero - +0.0160" TIR
Clearly, most if not all of my runout is occurring at the chuck. It is a high quality Bison 6" 3-jaw that I've had for a few years. Never had any apparent issues before now. I'm thinking I need to remove the chuck and give it a thorough cleaning, but thought I'd ask first. Am I missing something? Anything else I should test first with the chuck still in place? (I have a nice 6" 4-jaw that I could mount and check for runout.)
Thanks for any help.
Oh, and please disregard the trash on the lathe. I discovered this issue in the middle of working on a project.
Regards,
Terry
At 1-1/4" from chuck jaws - zero - +0.0044" TIR
At 4-1/2" from chuck jaws - zero - +0.0091" TIR
At 9-1/4" from chuck jaws - zero - +0.0160" TIR
Clearly, most if not all of my runout is occurring at the chuck. It is a high quality Bison 6" 3-jaw that I've had for a few years. Never had any apparent issues before now. I'm thinking I need to remove the chuck and give it a thorough cleaning, but thought I'd ask first. Am I missing something? Anything else I should test first with the chuck still in place? (I have a nice 6" 4-jaw that I could mount and check for runout.)
Thanks for any help.
Oh, and please disregard the trash on the lathe. I discovered this issue in the middle of working on a project.
Regards,
Terry