Cat 40 Arbours

[Susquatch]

Something of interest for you guys with bigger mills:

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[YYCHM]

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[Tom Fitzpatrick]

A question as I see these all the time here - what machine do Cat 40 milling holders fit? I have a 70's vintage Bridgeport vertical milling machine and it takes R8 tool holders for its arbor.

 

[Ironman]

Most larger milling machines use Cat40 or CAT50. R8 is not used because of accuracy issues. CAT40 and BT, the Euro version are not a big deal. They both use the 7:2 taper ratio so the difference is the driver ears. My mill has a BT spindle and I use Cat tooling in it because of ease of availability. I just unbolted one driver lug off the spindle and the Cat goes on.

 

[thestelster]

From what I understand as well, is #40NMTB like my Ex-Cell-O and many older manual milling machines can use CAT40 tooling, but you need either a longer draw bar, or make/buy an extension/adapter to replace the pull stud on the CAT tooling so that you can use your existing draw bar.

 

[Susquatch]

Cat 40 & 50 are both part of the bigger is better paradigm. I remind my wife of that daily but she has dedicated her life to undermining my ego.

Most of the popular Bridgeport are R8. But Cat 40/50 were available as factory options and some members have a machine so equipped.

This is MT3



This is R8:



This is CAT40



All 3 are 3/4" endmill holders.

 

[thestelster]

I think the largest spindle tapers that came in the Bridgeports were #30NMTB or #30 QC Ericson

 

[Susquatch]

I think the largest spindle tapers that came in the Bridgeports were #30NMTB or #30 QC Ericson

Could be Stel. They look a lot like CAT40 to a guy who doesn't have one. What did @Brent H have on his? And where is that guy anyway? We might need to sign him up for the NS Coast Gaurd so he has more time for us......

 

[thestelster]

He has the #30. When I saw it, I remember thinking that he should feed it more so it could grow up to the size of it's bigger brothers!

 

[Susquatch]

I see, well that explains that!

Now I wonder if the ones I have here waiting for you are 40s or 30s?

 

[trevj]

I see, well that explains that!

Now I wonder if the ones I have here waiting for you are 40s or 30s?

Easy to check, compare directly with the R-8 taper. Cat/BT/NMTB/etc. number 30 taper is a match for the size of the front taper of the R-8, which I figure is not likely to be entirely a coincidence.

We ran a mixture of BT and CAT holders on the CNC mill at my last work, it was indifferent to which were used, as tool changes were done manually. Gotta have whatever matches the tool changer fingers, otherwise.

 

[Alexander]

CAT 40 is standard on most American made CNC Machines BT 40 is on a lot of Japanese (Chinese) equipment. The groove for the tool changer is at a different Guage length and the drive dogs are different. I have been ordering some Cat 40 tool holders on Aliexpress for about $75 each. It is a good deal compared to buying used brand name holders.

 

[Chipper5783]

I think Alex nailed it. The groove for the tool changer is in a slightly different location - I can’t see mixing the two arrangements. I have a BT40 machine, and note that used BT40 is a rare item here in central Alberta (I’m see Cat40 all the time). If anyone is surplusing some BT40 tooling, let me know.

I am able to use the BT40 on my little European mill (Maho), with a shop built adapter from the M16 male to S20 male buttress (“Deckeldapter”) - of course being a manual machine the tool change groove is not relevant. It does mean I have a wide range of options for the little Maho.

The point being you can often mix/match tooling across the various #40 spindle tapers, but will need to sort out drive keys, the connection to the retention device, maybe the diameter of the driving ring, etc.

 

[trevj]

Yeah, the quickie visual cue is that the CAT holder has it's groove centered on a narrow band, while the BT has the groove offset with the one side far wider than the other. Has been the quick and dirty method of separating the two types for me.

Good infor here. https://www.cncsparetools.com/new/C...ences-between-BT40-and-CAT40-Tool-Holder.html

BT uses a shorter Taper length, so needs a longer pull stud, and BT usually uses a metric thread on it's pull stud.

IIRC, the CAT's use the two different size drive notches, as a means of indexing an offset tool, on machines that are capable of controlling the orientation of such, stuff like offset boring tools or boring heads.

And if you want to see "Cute" tooling, they make CAT down to CAT 10 size!