Re: Milling Machine Taper question

--- In CAD_CAM_EDM_DRO@y..., "Matthew King" <mattking@k...> wrote:

> I've got a slightly off topic question for you folks, if ya don't

mind.

>
> I've recently purchased a nice, old Milwaukee manual mill - it's

got an NMTB

> 40 taper with .625-11 (5/8-11) drawbar thread. What other tapers

can be

> used in this machine? Can a CAT 40 be used? It seems to have the

appropriate

> taper and drawbar(actually pullstud) thread, although it's missing

the

> "straight" area at the top of the taper. BT 40 seems to have the

right

> taper, but a metric drawbar/pullstud thread.
>
> Mine is shaped something like this:
>
> | | <------ this is the "straight" part that

isn't on

> a CAT40 taper, as far as I can tell...
> | |
> / \
> / \
> / \
> / \
> | |
> ---------------
>
>
> Can anyone help me out here? I need a decent collet holding chuck

for this

> thing to make endmill changes easier and they seem to be far more

readily

> available on the surplus market in CAT form rather than NMTB.
>
> Thanks!
>

Matt
This subject has been covered a lot on alt.machines.cnc
The concensus of opinion is that all the 40 series has the same taper.
All that differs is the pull stud thread, whether or not it has the
straight portion and the dimensions of the vee groove and drive peg
sizes.
You have correctly listed the NMTB and BT series. The CAT series is
unique in that it has one large drive dog and one smaller one so that
it can locate in the tool changer. For a manual machine you can
ignore this. So you now have a choice between the two types. If you
can change drawbars easily you can also use the BT40 series.

John Stevenson.