On Wed, 8 Apr 2009 16:21:42 -0400, "Joe AutoDrill" wrote:

This becomes painfully apparent in the larger taper and drill sizes:
If a #4 or #5 MT slips when driving a large drill the tang is easily
sheared off. With a #3 MT it depends on the type of tool. With # 2
MT and smaller the tang generally is of sufficient strength to drive
the tool in case of slippage.

Wolfgang,

Thanks for the heads up and info. I've never heard of a MT4+ shearing the
tang off, but I suppose it is possible now that you say it...

Absolutely, despite many folks firm belief, the tang has no part in torque
transmission. If the tang ever sees torque, you've already lost the grip.

One of the options I offer is a MT2 with a draw bar... I suppose the draw
bar makes the MT2 seat better even if imperfect... But the clenaliness of
the tapered surfaces is always a major concern for us. Acetone is what we
use but even that leaves a slight sheen of oil. (don't beleive me? Go clean
a mirror with it...)

A clean taper with a drawbar only needs the nut tightening hand tight/lightly
with a Morse taper. I actually wipe the tapers clean with a little way oil and
they still grip :-)


I'm looking to do a through-the-coolant application where the MT tooling
goes into a spindle that has a draw bar-like knock-out passageway to remove
the tapered tooling... And thus the tooling's tang will not have a slot to
knock it out because the liquid would escape!

Beware of soluble coolant, could end up rusting the taper together.



We had a drill press here a few years ago with a MT2 tang that was seated so
well, we bent the spindle trying to remove it and ruined the drill press.
Simply deformed the drifts into mangled pieces of steel.

'Nuff said about the holding of Morse tapers.

These thoughts are worth exactly what you paid for them.

Mark Rand
RTFM