Greg, Backlash, others: Thanks for the wealth of info - now I know a
bit on how to use it and how it works. I hope to be able to play with
it this week end. Since this is a small unit, the tap head chuck only
opens up to 0.25 inch, I need to rumage thru my misc tap bucket for a
spare or two that I don't mind sacrificing - it seems that I have many
more duplicate taps that are greater than 0.25 than smaller.

And no, I will admit that I did not even think of looking to see if
ETTCO was still in business, I just assumed that most companies have
either gone under or have been consolodated / renamed in the past 80
years. In looking in a couple of catalogs to see if I could visually
identify "gun" taps, I came across current ETTCO tapping heads.


"Backlash" wrote in message ...
All the tap heads I have rebuilt by Procunier and Ettco use a cork lined
double cone clutch and a set of planetary gears inside. The tap is driven
into the work by one side of the cone clutch until the body of the tapper is
stopped by a physical limiter on the drill press or other machine. The tap
loses driving friction at this point by the cone clutch disengaging, and
goes into a "neutral", which limits tapping depth. You can pause tapping at
this point if you desire, by keeping the head floating in this neutral zone,
with your feed handle. Whenever downward pressure is released, the other
face of the cone clutch, along with the planetary gears come into play,
reversing the taps rotation to back out of the hole. The gearing speeds up
this process of getting out of the hole more quickly. Once the tap clears
the work, it automatically switches directions via a coil spring against the
cone clutch to once again drive in a right hand direction. The screws you
see around the lower end of the tapping head are the spindles of the
planetary gears....