Difference between NMTB and NST tool holders?

[bcall2043]

I have a friend who is looking for NMTB-30 tool holders for his mill. The question came up about using the CAT-30 holder in place of the NMTB-30 holders. I found this site http://www.tools-n-gizmos.com/specs/Tapers.html with pictures and dimensions which seems to indicate that they will work okay except for the draw-bar length because the CAT version is shorter than the original NMTB version. The CAT version does not have the straight nubbin at the draw-bar end but the CAT internal thread for the tooling adapter that fits there is the same as the draw-bar thread.

While performing a search to see what a bargain price might be for the holders for his machine I ran into another question that I could find no answer for. The new question is how a NST tool differs from a NMTB tool? This link http://www.victornet.com/alphabetic/Arbors-NST-National-Standard-Taper-/1421.html?id=epyp2a7X shows a holder that appears to have the same draw-bar nubbin as the NMTB taper but maybe some differences. The following note in their ad seems to indicate they are not the same:

“NOTE: these are standard NST taper holders. If you need NMTB quick change holders (for Erickson system) please call.”

Can anyone provide any information on what the differences are?

Benny

 

[Tony Wells]

The main difference is in the flange. The taper is the same. The drawbolt threads are the same. The length of the drawbar might be different. The flange has drive slots for the drive bars or lugs.

Some use a pull stud instead of a drawbar, and use a air or hydraulic system to pull then into the spindle.

Many of these are interchangable, some with a little modification

 

[brt]

Nmtb-30

The main difference is in the flange. The taper is the same. The drawbolt threads are the same. The length of the drawbar might be different. The flange has drive slots for the drive bars or lugs.

Some use a pull stud instead of a drawbar, and use a air or hydraulic system to pull then into the spindle.

Many of these are interchangable, some with a little modification

I got the ER40 collet holder and a bunch of fixed-sized holders from Shars: http://www.shars.com/product_categories/search/?search=nmtb+30

 

[Chazz]

The 'National Machine Tool Builders' association desined a 'National Standard Taper', (the following is a quote from Wikipedia) "The taper is variously referred to as NMTB, NMT or NT. Essentially this defines a taper of 3.500 inches per foot or 16.5943 degrees[SUP][2][/SUP] (also referred to as "7 in 24" or 7/24). All NMTB Tooling has this taper but the tooling comes in different sizes. NMTB-10, 15, 20, 25, 30, 35, 40, 45, 50 and 60. With the 40 taper being the most common by far."

The Erickson Tooling Company designed a NMTB 'Quick Change' Tooling system requiring a unique 'Erickson' spindle.

HTH
Chazz