Arch wrote:

4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?



The JTs that the chucks mount on are Jacobs tapers, not Jarno. The
Jarno tapers are long tapers very similar to Morse tapers.

The Jarno tapers are easier to machine than the Morse as they all have
a .600" per foot taper. The Morse tapers are around the same, but vary
for each size.

A Jacobs taper will hold very well if it is installed correctly.
Perfectly clean surfaces, free from burrs, is often enough. To get
them tighter, heat the female part in an oven and then drive in the
male arbor.

Here is a link to a good table of tapers:

http://www3.telus.net/public/aschoepp/tapers.html

John Martin