NMTB40 vs BT40

[ddickey]

Anyone use one or the other or both?
My mill is NMTB40 but what I'm seeing is BT40 is plentiful and a little cheaper.
Before I start to invest in tooling I'm considering making a new drawbar and buying BT40.
Opinions?

 

[Martin W]

I think the drawbar need to be metric for BT40? Also about a 1/2” longer also
Cheers
Martin

 

[Superburban]

Yes, the BT standard is metric. My mill uses the NMTB50, and I have come across some that fir in all other dimensions, but are 5/8" thread, instead of the 1". And many that are not marked at all. The NMTB's should have the straight section on the drawbar end, that is what I look for on E-bay. it generally works.

Here is a good reference

Machine Tool Shanks (Tapers)

 

[ddickey]

I guess I could start buying both.
and just sue two drawbars then.

 

[mmcmdl]

Which one is metric ? I think I have 5/8-11 threads in the 40s ?

 

[ddickey]

BT and ISO are metric.
NMTB and Cat 40 are imperial thread, both 5/8-11 thread I believe.

 

[mmcmdl]

I have a few NMTBs after reading an older post . One is a 4" boring head , I was wondering if the head was removable from the adapter .

 

[Superburban]

BT and ISO are metric.
NMTB and Cat 40 are imperial thread, both 5/8-11 thread I believe.

You have to watch, there is also an ISO/DIN something or other, that looks just like the CAT with the V flange, that is metric.

I find it amazing that a company puts so much into making these, yet few have brand names, And some do not even have the tool size marked on them. I would think they would be proud, and want their name on them, so companies might buy more.