Tooling for 40 taper mill

PT Doc said:

CAT40 tooling seems to be more readily available than NT40 from suppliers like MariTool and Glacern. Makes sense since Haas machines use CAT40. I have been reading a bit through old posts about modifying the drawbar and keys of a NT40 machine to convert it to use CAT40 tooling.

If you were able to buy a good quality 5hp milling machine with NT40 spindle taper, would you convert the machine to accept CAT40 tooling? I have neither NT40 nor CAT40 tooling at this time.

Thanks in advance.

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tnmgcarbide said:

no.


why? they cost relatively the same new or used.

unless i had some specific reason to.... like i already had a supply of cat40 tooling on hand
or someone offered me free ct40's ...

are you implying that you already have a Haas mill?

Which 5hp quality nt40 mill are you modifying?

are maritool and glacern the only vendors from where you can buy tooling?

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thermite said:

I have more NMTB 40 than CAT 40 but don't pay much mind to it for an all-manual mill.

BT40 or Ericsson I DO still avoid, but even those would not be "show stoppers"

CNC with pull-studs, toolchanger, and magazine is where it REALLY matters.

If you don't yet have any major investment nor "count" in NMTB 40? I'd go CAT 40 and sell or trade-way the fewer older ones as are not special or uncommon just to reduce even the MINOR nuisance.

20CW

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PT Doc said:

Since I have neither NT40 nor CAT40, I would have to make a commitment to either or. So it seems like now is the time to decide.

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tnmgcarbide said:

while that's terrific you've decided on one over the other.... i'm curious to hear of the
unavailable tooling in nmtb-40 . i have facemill arbors, Tg-100 chucks, er-32 chucks, er-16
chucks, solid endmill holders . only thing missing is shrink-fit endmill holders, which
wouldn't do me much good @4200 rpm anyway.

good luck on your new mill purchase.

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thermite said:

One actually doesn't "have to" make any sort of "commitment" at all, with those two as the options.

But skew the new buys to CAT 40, anyway.

Pull one driving lug off the spindle nose - done ages ago, here - NMTB still fits if you need that for an oddball not to be found cheaply anywhere else, and done.

It is an easily reversed decision, after all.

Lug can stay off. Drawbar "may" even be made dual-use easily enough.

CAT was just the first mod to NMTB 40 so automatic toolchangers could work with it. The Metrifuckated 40-taper tribe are the ones with the weird-arseholes.

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PT Doc said:

Thanks for pulling key recommendation. I haven’t seen an NT 40 mill in person nor have I seen either holder. According to drawings, 1.1” longer holder for NT40.
Thank you for your input.

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gbent said:

If I were to buy a mill with a 40 taper and loose drawbar, and I needed to buy new toolholders, I would buy Cat 40 toolholders. This would require making a new drawbar that is about 1 inch longer than the old drawbar. This way if I were to upgrade to a CNC I would already have toolholders. To utilize standard NMTB 40 holders you simply need to use a 1" spacer under the drawbar to shorten it to original length.

You will need to modify one drive key on the spindle. On Cat holders, one drive notch is less deep. That notch is marked with a drill point or a short bore to achieve balance. If you remove one key, you have to index your toolholder properly each time. If you modify (shorten) both keys, you don't have to worry about a wrong index, plus it maintains spindle balance.

Erickson QC 40 toolholders are standard NMTB 40 toolholders. The only difference is the drive flange is qualified both sides to fit the QC locknut.

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