Critical finish in ID sphere

[ncassist]

I'm trying to get a "mirror" finish in an internal spherical dish in aluminum. Diameter is about 3/4 inch and depth is about .200 inch in 6061 aluminum in CNC lathe. So far the best we can do is machine and "lap" by finger with car polish. Anyone got any ideas?

 

[unclesyd]

Take a look at Semichrome Polish. It is available from these and other people and is in a lot of the bigger hardware stores and some auto supply stores. We polish Al reflectors all the time.

http://www.winterbrookfarm.com/restore.htm

 

[Nate101]

Try an industrial diamond tipped round insert (PVD) for a finishing tool. These are a little pricey but they last forever in aluminum and it's faster than lapping.