View Full Version : Cat 40 taper

02-27-2003, 10:18 PM
Anybody know off hand if a cat-40 mill taper can be converted for use in a 40-NMT spindle?

T Wise
02-28-2003, 07:58 AM
I've used them in our mill, it has an adjustable drawbar that allowed it to extend longer to make up for the shortened length, as far as I know the taper is the same. No reason why you couldn't make an adapter stud.

03-06-2003, 04:43 AM
The Cat-40 uses a 1/2-13 Pull stud and the NST-40 uses 5/8-11 drawbar. It is also important to note that the Cat-40 requires a tight fit of the keys to the key slots - you may have to replace them or modify yours. With the smaller pull stud it is easier to turn the toolholder in the socket - hence the requirement for a tight fit of the keys.

So they will work with a new drawbar and possibly new torque keys on your spindle. It would be a good idea to consider a socket cleaning tool like the Spindle Mate (expensive, but it can recondition the surface of your socket if rough and keep it clean).

[This message has been edited by Thrud (edited 03-06-2003).]

T Wise
03-07-2003, 09:57 PM
sorry, but cat 40 uses 5/8-11, looked it up in that new book you recommended. cat 30 uses 1/2-13 thread. There's another taper that uses a metric pull stud that's close to cat 40 but I'm not sure what it's called.

03-07-2003, 11:04 PM
I found one on Ebay and took the chance it came in with a 5/8-11 thread works okay I made a new draw bar an 1-1/4"longer out of some B-7 round bar and then made a hardened steel spacer the same length so I can use my other endmill holders as the cat-40 doesn't have the same projection on the end.Thanks for the help.

03-08-2003, 02:31 AM
T Wise:
Thanks for the correction, I was thinking of the flange bolts for some stupid reason. Looked it up and you are correct.

A drain is a terrible thing to bamage. http://bbs.homeshopmachinist.net//biggrin.gif

There are lots of good deals on eBay for them - including Wohlhaupter boring heads and Lyndex collet chucks(on occasion).

03-08-2003, 08:57 PM
Hmmm...boring heads..yes...must have boring head!