Shop made arbor for Atlas Mill

[JPMacG]

I just finished a 1" arbor for my Atlas MFC mill. The project was easier than I expected and the runout on the arbor is better than I expected - about .001" TIR. Total cost was $60 for materials, which included shipping. It was all done between centers on my Craftsman (Atlas) lathe. I'd be happy to discuss the order of operations if anyone is interested.

Material for horizontal mill arbor

I'm thinking of making my own 1" diameter arbor for my horizontal milling machine. This involves cutting stock to length, threading one end, and turning a few diameters. I want to start with precision ground rod with good straightness. Would this material be suitable? If not, what would you...

www.hobby-machinist.com

 

[dockterj]

Looks nice! I need to make one as well. I've not turned between centers much. Were you able to get both centers drilled concentric to the OD? If you had to do it over again would you buy oversized stock and turn down to 1" between centers?

I have some 1" shaft that I might try your design on (thread and pin a drive plate on). I've not turned a taper before. It should be a good project.

 

[JPMacG]

Hi DockterJ,
Getting the centers on-center was important, as I was using 1" stock and not turning it down. I carefully centered the stock in a 4-jaw using a dial indicator. Then installed a steady rest on right side of the stock and moved the dial indicator close to the end. I used the jaws of the steady rest to force the stock to run true. It took some time and fiddling with the jaws, but eventually I got the stock to run with essentially zero runout. Then face and drill the center as usual. Then reverse the stock in the 4-jaw and repeat the process.

Next was to test the runout between centers. This was a learning experience. I chased my tail for a while before I learned that my old headstock dead center (MT2 center with an adapter to MT3) had some runout. I purchased a new MT3 dead center. And I learned that my live centers for the tailstock were less than perfect too. I used the best one of the two I had.

Final result was that the runout of the stock between centers was less than .001 at both ends and center - about the limit of my measurement capability. This was much better than I expected. I tried to do everything the best I could, but in the end I think I just got lucky.

I think that starting with precision ground tight tolerance rod was a good idea. I doubt that I could have achieved the tolerance and surface finish myself turning down larger stock. Installing the drive bushing as a separate part added some complication, but not that bad.