Last week I went to a local machinery auction and for once there were
more lots than interested bidders. I bid and won a bench grinder for
$5, the auctioneer included the two prior lots that did not sell for
$5. One of those two lots consisted of an antique tapping head. The
brand name is ETTCO, Eastern Tube & Tool Co. w/ a patent lable of Aug
1924. I have never used a tapping head before - I have occasionaly
tapped using my Bridgeport w/ a tap in a collet. In playing with the
tapping head by hand, I have been able to make it reverse direction
but I am unsure of exactly what makes it change direction - is it
torque based or is it when the unit receives an axial load (tap
botomed out)? Do tapping heads typically have any adjustments? THere
are a couple of set screws that might be intended for ajustment but
there are no markings on the body nor any indication that there has
been frequent adjustments made to these set screws.

BTW, a mini gloat. I had 6 winning bids, all of them bottom feeder
types for odd lots. One of them was for a box or boring bars for $5
(there was only one bar in teh lot that I could use on my 12x36
Clausing. I resold the boring bars the next day. As I was loading
stuff into my vehicle to the people that bought the huge Monach lathe
for $100 (no joke!) came by and offered me $30. I bought a lot of misc
electical for $5. The lot consisted mostly dirty extension cords.
Under the pile of cords was a small, 1.2A Dumore hand grinder - that
works good!