CAT-40 vs. BT-40

[colton_m]

Hey gang,

I did some searching and there seems to be a lot of different, contradicting answers to this question... Hopefully someone can shed some more light?

I am curious as to what the differences are between CAT-40 and BT-40 tool holders?

As far as I can tell, the only differences are that the pull-stud threads on BT's are all metric and the location on the V-flange for the tool changers is differnt from CAT. Is this all? I have also heard that BT tooling locates on the taper as well as the face of the spindle. Can anyone confirm this?

Finally, I suppose my main question would be is do BT holders provide a higher level of accuracy over CAT holders? And if so why?

HAAS offers both spindles, I'm assuming there has to be a reason for the two different types of holders from a functionallity standpoint and not just someones need to be "different".

Thanks,
Colton.

[Geof]

As far as I know the functionality difference is just the flange for the toolchanger. They both contact the same on the taper and use the same drawbar tension and both locate only on the taper. A difference is that the notch for the drive dogs are different and if the spindle dogs are set up correctly this one can only fit in the spindle in one orientation, but the Haas spindle can take both in either orientation. I think the alleged superiority of one over the other is self-delusion.

[rowbare]

Offering both CAT and BT is a legacy issue. Most shops will use one or the other. This is quite often dictated by what the first machine they bought had. As Geof said, the differences are minor.

There was a thread here not too long ago about converting a HAAS from one to the other. http://www.cnczone.com/forums/showthread.php?t=98263

bob

[gonc]

Some claim that the BTs are balanced better because the drive dogs are the same size on each side. I have a Super Mini Mill 2 with CAT and a VF-0E with BT, other than the items listed below, there isn't much of a difference. Costs are about the same for both and there are more used CAT holders out there than BT. I already had the 0E with BT before I special ordered the MiniMill2 with CAT. I don't have a higher preference for one or the other.

[aadrew10]

I have used a BT40 in a few CAT40 haas machines. The only difference you need to be aware of is the tool changing flange. You can use the holders, but if you try and change tools it will mess things up. I only used it because I couldn't find a 25mm tool holder with a CAT40 flange except from US shop tools, and then they still sent me the BT40, so I decided not to buy from them again, but that's another story. The BT40 holders rest only on the taper, not on the flat side of the spindle. Thats the whole point of having a taper.

- Andrew

[Eric MFG]

I use both BT40 and CAT40 the only difference is the spindle dog slots on the holder. Think on the BT40 holder one dog slot is shorter also on our BT40 spindle machine the CAT40 holders go in one way. There is a dimple on the holder and on one of the spindle dog just line the two dimples up. Or might be the other way around don’t remember, I know when you look at the holders side to side you can see the difference in the spindle dog slots. I can have a look at the holders Monday and get back to the thread.

[dcoupar]

Originally Posted by Eric MFG I use both BT40 and CAT40 the only difference is the spindle dog slots on the holder.

Not true. The flange is different too (see attached).

[haastec]

Originally Posted by Eric MFG I can have a look at the holders Monday and get back to the thread.

It's been a couple years since the last post, so I think they may have sorted it out by now.