What is it? Mt3 with 12x1.75 mm threads and Jacobs taper?

[Mr_Bill]

this is a MT3 taper with a 12X1.75 mm internal threads. The taper on the other end is .626 on the big end and .580 on the smal end and that taper is 1.1" long. Is it a Jacobs taper? It had a drill chuck attached at one time. What peace of equipment was it used in?


I also have this item Smithy MT3 taper with 3/8" -16 internal threads and the other end has either a 7/8-20 thread or it may be a 22x1.25 mm thread. What peace of equipment was it used in?



Thanks for the help identifying the items.

Bill in Cincy

 

[sfriedberg]

this is a MT3 taper with a 12X1.75 mm internal threads.What peace of equipment was it used in?

Any machine that takes MT3 arbors with a 12mm drawbar. Probably a milling machine or dedicated specialized drilling machine rather than a generic drill press. Could be any one of hundreds of obsolete models. Furthermore, such machines can easily have different drawbars fitted, so the 12mm thread is not a strong clue in any way.

The taper sounds like a JT33 Jacobs taper from your measurements, although they are not an exact match to the specs. The fact that it was holding a drill chuck is a strong clue that it's a Jacobs taper!

I also have this item Smithy MT3 taper with 3/8" -16 internal threads and the other end has either a 7/8-20 thread or it may be a 22x1.25 mm thread. What peace of equipment was it used in?

Not trying to be sarcastic, but it was used in a Smithy combo machine! The 3/8" internal thread is a drawbar to hold the arbor in during milling-type operations, and the 7/8-20 probably fits a boring head. IIRC that's a fairly common thread for such things.

 

[metalmagpie]

The piece threaded 7/8-20 is a shank for a 2" boring head.
The internal threads are for a drawbar.

metalmagpie