NC Rick
Aluminum
- Joined
- Oct 7, 2007
- Location
- Asheville, NC
Hello folks,
I'm hoping I can indulge myself here and ask for some of your experienced input. I'm attempting to learn from a very simple project which is outside of my experience. Honestly, I felt this was so basic, I posted on the hobby machinist site with some questions and details of what I was up to. It seems I may be even worse than I thought at this stuff and from what I was told, if my technique isn't way off, I may have a problem with my lathe. Although my equipment is 50+ years old, I'm more suspect of my skill level.
Anyhow, my objective was to make an adapter plate to allow me to mount an 8" three jaw, plain back, scroll chuck to my 12" Yuasa rotary table. I purchased a 10" x 1/2" gray cast iron disk from McMaster Carr and wanted to face it off to be reasonably parallel between sides. I used my 12" 4 jaw chuck with some adjustable stops to enable me to grab just a little of the O.D. at a time. I think I would have been better off with a 3 jaw chuck...
Anyhow, after some screwing around I got the disk to within under a 0.001" in all the ways I could measure it. I was pretty happy. Measuring shows I managed to turn a bit of a cone (by about .0005" over the 5" radius of the part). I feel certain I could do a better job on the flip and turn methodology next time and I think it took me too much time learning to get this faced.
I am being told that the lack of accuracy I produced is bad enough that no one would be able to use a lathe of such low standards in accuracy. I really don't know what I should expect. I would have been pretty okay with anything inside of a couple thou.
Can you folks clue me in to what kind of parallelism and accuracy I should expect from my machine and from my limited experience? I do know that having the Chuck on the rotary table is proving to be a very nice feature for what we do.
Thanks!
The included photo is a quick map of some micrometer readings I made on my disk this morning. I did put it flat on a surface plate as well and it confirms the outer edges being "high" fairly equally.
I'm hoping I can indulge myself here and ask for some of your experienced input. I'm attempting to learn from a very simple project which is outside of my experience. Honestly, I felt this was so basic, I posted on the hobby machinist site with some questions and details of what I was up to. It seems I may be even worse than I thought at this stuff and from what I was told, if my technique isn't way off, I may have a problem with my lathe. Although my equipment is 50+ years old, I'm more suspect of my skill level.
Anyhow, my objective was to make an adapter plate to allow me to mount an 8" three jaw, plain back, scroll chuck to my 12" Yuasa rotary table. I purchased a 10" x 1/2" gray cast iron disk from McMaster Carr and wanted to face it off to be reasonably parallel between sides. I used my 12" 4 jaw chuck with some adjustable stops to enable me to grab just a little of the O.D. at a time. I think I would have been better off with a 3 jaw chuck...
Anyhow, after some screwing around I got the disk to within under a 0.001" in all the ways I could measure it. I was pretty happy. Measuring shows I managed to turn a bit of a cone (by about .0005" over the 5" radius of the part). I feel certain I could do a better job on the flip and turn methodology next time and I think it took me too much time learning to get this faced.
I am being told that the lack of accuracy I produced is bad enough that no one would be able to use a lathe of such low standards in accuracy. I really don't know what I should expect. I would have been pretty okay with anything inside of a couple thou.
Can you folks clue me in to what kind of parallelism and accuracy I should expect from my machine and from my limited experience? I do know that having the Chuck on the rotary table is proving to be a very nice feature for what we do.
Thanks!
The included photo is a quick map of some micrometer readings I made on my disk this morning. I did put it flat on a surface plate as well and it confirms the outer edges being "high" fairly equally.