Hood,

Yes, a Beaver thread would be great. with lots of pics.

BTW,  Yes, I'm old, but I'm  not dead.   

Ed

mine too.  NMBT40 W/ Power draw bar

Ed

A little off topic, but is there a way to get a cat 40 or bt 40 collet to fit a nmtb 40 spindle?

Vince

Not sure what NMTB40 is Vince, dont think we have such a beast here, or maybe we just call it something different. My mill can accept any 40 taper tooling as far as I know, the two things I would have to do is for CAT/DIN is either remove one of the dogs or mill a bit off to make it fit in the shallow notch on the holder. The other thing is I needed to make longer pullstuds as the Int40 taper has an extended shaft. Below is a pic of the original pullstud (right)  the extended one I made (left) and also one I made for a friends mill.
Hood

An NMTB40 does not have a pull stud.  The spindle has a draw bar like a bridgeport j head.  The draw bar screws into the top of the collet.  If all the 40 tapers are the same then I guess I could make a collar that screwed into the CAT 40 and then the draw bar could screw into that.  I was wondering if someone had ever done that.  NMTB tooling is very scarce but CAT 40 and BT 40 are much more readily available.  I'm in York right now for the Mach seminar. When I get back I will post a picture of a NMTB 40 collet.

Vince

N4NV,

NMTB 40 holders do not have the groove in the flange which is used for a tool changer.
it is just an older style for use with a 5/8-11 draw bar

all 40 tapers are the same. you may need a longer drawbars.
Check out the specs on this site.

http://www.tools-n-gizmos.com/specs/Tapers.html#CAT

Ed

Ah ok thats just like what I know as Int40 except most of mine have M16 threads although I do have some with 5/8".
 I have been buying DIN69871/A which is the same as CAT but with a metric thread as I plan to make a toolchanger for the mill at some point in time.

Hood

Thanks for the information Ed.  i think I will try to make an adapter collar what will fit into a Cat 40 so I do not have to change my draw bar.  It looks like a good project to test out threading on my lathe.

Vince

Also,
 NMTB 40 HOLDERS  are still made. Bison of Poland makes a good quality holder, and the price ain't bad.
Some  40 taper machines spindles are threaded and use a big nut to hold the holder in, and some must have the holder flange machined narrower to work. a Spanner wrench is required to tighten the nut. BUT, eliminating the nut , you can use any 40 taper holder , if the spindle has a hole through for a draw bar. (some machines don't ) 

Ed

More on 40 taper.

CNC Milling machines will nearly always use SK (or ISO), CAT, BT or HSK tooling. SK tooling is the most common in Europe, while CAT tooling, sometimes called V-Flange Tooling, is the oldest variation and is probably still the most common in the USA. CAT tooling was invented by Caterpillar Inc. of Peoria, Illinois in order to standardize the tooling used on their machinery. CAT tooling comes in a range of sizes designated as CAT-30, CAT-40, CAT-50, etc. The number refers to the Association for Manufacturing Technology (formerly the National Machine Tool Builders Association (NMTB)) Taper size of the tool.
CAT-40 Toolholder

An improvement on CAT Tooling is BT Tooling, which looks very similar and can easily be confused with CAT tooling. Like CAT Tooling, BT Tooling comes in a range of sizes and uses the same NMTB body taper. However, BT tooling is symmetrical about the spindle axis, which CAT tooling is not. This gives BT tooling greater stability and balance at high speeds. One other subtle difference between these two toolholders is the thread used to hold the pull stud. CAT Tooling is all Imperial thread and BT Tooling is all Metric thread. Note that this affects the pull stud only, it does not affect the tool that they can hold, both types of tooling are sold to accept both Imperial and metric sized tools.

SK and HSK tooling, sometimes called "Hollow Shank Tooling", is much more common in Europe where it was invented than it is in the United States. It is claimed that HSK tooling is even better than BT Tooling at high speeds. The holding mechanism for HSK tooling is placed within the (hollow) body of the tool and, as spindle speed increases, it expands, gripping the tool more tightly with increasing spindle speed. There is no pull stud with this type of tooling.

The situation is quite different for manual milling machines — there is little standardization. Newer and larger manual machines usually use NMTB tooling. This tooling is somewhat similar to CAT tooling but requires a drawbar within the milling machine. Furthermore, there are a number of variations with NMTB tooling that make interchangeability troublesome.
Boring head on Morse Taper Shank

Two other tool holding systems for manual machines are worthy of note: They are the R8 collet and the Morse Taper #2 collet. Bridgeport Machines of Bridgeport, Connecticut so dominated the milling machine market for such a long time that their machine "The Bridgeport" is virtually synonymous with "Manual milling machine." The bulk of the machines that Bridgeport made from about 1965 onward used an R8 collet system. Prior to that, the bulk of the machines used a Morse Taper #2 collet system.
AND ,  Some used a #9  or #10 brown and sharpe taper.

Ed