According to Tom :
"DoN. Nichols" wrote:

[ ... ]

O.K. I see where some of the confusion came from. The manual
calls the Jacobs taper on the end of the spindle a Morse taper -- which
is totally incorrect.

[ ... ]

Actually it could be correct, Don.

According to Jacobs:

"DIN Taper Interchangeability
DIN tapered sections are identical to the following Morse tapers:

MT No 1 for tapers B10 and B12
MT No 2 for tapers B16 and B18
MT No 3 for tapers B22 and B24

The length of these tapers is, of course, distinctly less than the
overall length of the corresponding Morse taper. Each taper may be
regarded as corresponding approximately to that part of the Morse
taper nearest the small end(for example: B10), or to the part nearest
the large end (for example: B12)"

Intersting information. Of course, it still should not be
*called* a Morse taper, as that leads to the expectation of a socket in
the spindle, and a certain length, neither of which is met.

I wonder whether the choice of basing the DIN tapers on the
Morse tapers is because there were plenty of precise gauges already
around for checking the taper?

And I'm still wondering where that 2-1/2 Jacobs taper came from
on the machine's label -- and a taper which appears to be closer to that
than anything else, even though there is no mention of a 2-1/2 Jacobs
taper in _Machinery's Handbook_ -- at least not in the 25th edition.
Just a "No. 2 short taper", which is not truly a half of a #2 taper. :-)

Enjoy,
DoN.
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