On 06.03.18 23:05, Gene Heskett wrote:
> It appears that its well nigh impossible to get a firm enough grip on a 
> tap shank, and on the smooth, unkeyed TTS ER-32 holder, to reliably lock 
> a tap for rigid tapping.  I've considered buying ER-32's with square 
> sockets, but for >8mm taps, the TTS adapter/holder will spin in the R8.

The only thing I could suggest is the guts of some "tap-hats" I made -
that's just a length of 1/2" round drilled/bored to take the tap shank,
and cross-drilled & tapped for four 3mm grubscrews to tightly grip the
square. That should go into a collet nicely. You could perhaps slit
longitudinally for that application, but a good tap fit should make that
unnecessary. Concentricity will be better if the outside is turned,
remedying both stock out-of-roundness and chuck eccentricity, I figure.

As I used them manually, I had a drilled hole in the back, to slip over
the drill bit still in the mill/drill chuck, for plumbing during hand
tapping of the hole just drilled. A slice of 1" round, drilled to fit
over the 1/2", and slotted externally to take the screws of a 1"
dieholder slipped over, was added for manual tapping. (I've yet to find
an adequate tap holder, and the die holder doesn't get in the way of the
plumbing hole in the top.)

The DIY path ensures you don't clutter the place with too many of 'em.
I've only made three so far. (Made mine in brass, as it's delightful to


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