I'm a newcomer to this site and machining in general. I just bought a Kearney & Trecker S-15 Model 310 milling machine with a 50 taper spindle. I'm now looking for tooling for this 100% manual machine.
What is the difference between CAT, BT, NST and NMTB tapers?
What kind of taper does this vintage of Kearney & Trecker utilize?
NMTB, also known as NST.
NMTB is a bastardization of the National Machine Tool Builders Association
founded in 1911
Everything else you mention is johnny come lately
Do you have any idea of the year of mfg for the machine? More than likely it's NMTB 50. Cat came later and is short for Catapillar taper. It's the predominant taper nowadays on new machines. BT is a Japanese taper, don't see it too much.
If we can nail down for sure that it's NMTB 50 I can get you some great prices on tooling.
I sell tools to forum members at near cost out of courtesy.
For what it's worth my understanding is that NMTB is the same as ISO or BT or NT. They are all a 31/2" per foot taper. The standard defines the spindle hole and not the adaptor or arbor that you night want to fit into it.
There are features on the adaptors which are not defined by the standard and which may prevent the taper "meshing" with that of the spindle.
For instance the cylindrical draw-in section on the end of the adaptor may not fit into the hole allowance in the spindle.
I also understand that variations like the CAT ones differ in the small "VEE" notch in the collar which is peculiar to certain CNC machines which use their standard for gripping the adaptor for tool changing.
Machinery's handbook and many other worthwhile texts provide descriptions of most of the used sizes ranging from ISO or NT 30 to 60 in increments of 5.
The NMTB tapers have SAE/USA drawbar threads.
The Cat and BT tapers have metric drawbar threads.
That is the quickest division.
Or otherwise stated, Cat or BT should work with a diffferent length and thread drawbar. Differences also appear in the drive ears.
You'll also visually recognize the NMTB taper because of the straight (parallel sided) round pilot added onto the drawbar end of the taper. The Cat and BT are truncated cones only.
At least on 40 taper tooling the tapers are the same, meaning the tooling will fit in the spindle but the location and size of the drawbar threads vary, and there may be drive lug incompatibilities as well.
My Nichols horizontal mill requires a different drawbar for NMTB and CAT tooling- CAT is 5/8-11, NMTB is 1/2-13. The CAT threads start about 1" further into the tooling than the NMTB. The Nichols OEM arbors have yet another thread.
OEM Nichols arbors have some tapped holes on the front face of the spindle, put a capscrew in to engage the drive lugs and things work- but thats specific to Nichols mills. On on a spindle nose with drive lugs specific to one family of tooling may well interfere with another.
Hi Greg, Did the drive lugs on your Devlieg line up alright with the cap screws on the Nichols spindle. It was a Cat 40 with the 5\8" 11 right?
Cat and BT tapers come with either inch or metric threads, depending on what you order.
I think we have to determine what type of tool retention the asked about machine has before we start to tell Gibbonsmike 1957 what type of tooling he should be looking for.
What taper is it?
What kind of tool retention does this machine have?
Is the draw bar inch or metric?
Is it a draw bar or a collet?
Just reread his post, 50 taper.
Now we have to figgure tool retention.
Collet or threaded drawbar.
To re-answer the question, the old K&T will use NMTB #50 tooling. The drawbar that came originally with the machine likely had both 1"-8 and 5/8-11 threads on it - to accomodate both #40 and #50 stuff - just like the earlier K&T mills.
Hi James- the Devlieg head has cat40. The spaces for the drive lugs look similar to NMTB/NST but are slightly different- the 2 notches on the Devlieg cat40 are not the same radial depth, so the lugs on the spindle nose will be of different sizes. I found the longer of the two lug notches will clear a socket head capscrew (5/16-18 x 1/2") in the spindle nose, so at the moment I have just 1 screw installed.
The lugs on the NMTB tooling I have clear the capscrew- so a single "lug" will drive both types of tooling. But I will need 3 drawbars, one each for english CAT, NMTB and Nichols.
Listen to Mr. Oder, your S-15 will take NMTB 50 tooling, which goes cheap on ebay but weighs a ton. Please post a pic in the K&T Heavy American Iron section of your new find. There aren't a lot of us around here with late K&T stuff. (S-12's & S-15's)
I want thank EVERYONE who responded to my post. It is very clear to me that I joined the correct FORUM The experience and expertise present on this Board is very apparent.
Sugar Land, Texas