What is the difference between MTA and MTB morse tapers?

MTA and MTB refers to whether a morse taper arbor is tanged or threaded.

What does MTA mean?

MTA means Morse Taper type A, the tanged variety of morse taper.

What are tangs on a morse taper for?

In short, a tang helps facilitate the removal of an arbor from its housing. Contrary to common misconceptions, it does not assist in transmission of torque, nor does it lock the taper into place or otherwise affect performance or grip.

What does MTB mean?

MTB refers to morse tapers that are threaded for use with a draw-bar/push-out bar. The drawbar provides an extra level of security beyond the friction fit of the morse taper. This is useful for milling machines where the morse taper arbor can be subjected to high lateral forces that could dislodge the arbor from its housing.

However be warned that it is possible to over-tighten a drawbar which can make it nearly impossible to remove without risking damaging the spindle bearings.

What is the difference between MTA and MTB?

The MTA vs MTB distinction refers only to the long end of the arbor, e.g the end that fits into the drill press or tailstock. It does not refer to or affect the functionality or specifications of the short end, e.g. the end the drill chuck is attached to.

Why should I choose a tanged morse taper over a drawbar?

Tanged morse tapers are most suitable when a morse taper is likely to have be regularly changed, and where the morse taper is seated horizontally and so is much less likely to fall out and damage a tool bit. E.g. for lathe tailstocks.

Threaded morse tapers are most suited for when a morse taper is unlikely to be regularly changed, and for when the morse taper hangs vertically and is subject to lateral forces which could see a non-threaded morse taper fall out