What you possibly may consider is using a 3/8" dia solid carbide boring bar in a smaller boring head. Carbide bars are 5X stiffer than steel ones so the finish is typically far superior. The rule of thumb for good finish is to bore 2x deeper than the bar dia with steel bars and 10x bar dia with carbide max. This rule is for steel parts,, you can go at least 30% deeper with aluminum parts.
If you make this as a 2 piece job,, sounds like the tube would lend itself better to lathe work rather than mill. |