RoyJ wrote:
Hope someone can settle an argument: The part is a 1" long x 3/8" OD x
3/16" ID brass bushing that needs a 6-32 set screw. Tap drill goes all
the way through both walls for convenience. Hand tap with straight flute
tapered tap and 'T' handle. Quick prototype level part, only making 2
of them, precision not required.

Questions: tap dry or use what lubricant? Backup the usual 1/3 turn to
break the chip necessary on this part?

There must have been a hundred students at school that have taped
3/4 brass "hammer heads" with 3/8-16 threads over the last many
years without a drop of fluid and without a single "backup" of
the tap. :-)
Also a large number that have done a blind hole in 1/2-20 about
3/4" deep.
If a material dosent make stringy cuttings, no need to back up
a tap. Even if it does that is what a spiral point tap is for. :-)
...lew...