What is the diffrence between pull stude types?

[l u k e]

Haas offers CT40 and BT40 pull studs, is there a performance difference? The price seems to be the same, so why would one be choosen over the other?

[HuFlungDung]

One fits CAT40 holders and spindle, while the other fits....you guessed it, BT40 holders and spindle They are not interchangeable, you must get the correct ones for your spindle.

[l u k e]

LOL, well I kind of guessed that part.

What I was getting at is when you purchase a mill you get your choice of spindle/pull stud size. Is one better than the other?

[PBMW]

The choice is between a Cat or a BT taper spindle. The pull studs are specific to each one. You can not interchange them. BT is more popular outside the US. Cat tapers are more popular in the US. At least I think so. I know it's not so easy to get BT tooling here as Cat tooling. I don't really see any perfomance advantage though. Get what is plentifull in your area.

[Geof]

These replies puzzle me, so let me explain why.

A while back I ordered a VF2 through my dealer, and within a day or so a message came from the Haas factory that they had an order cancellation on a machine that was palleted and crated ready to go to Korea; the specs were very similar to what I wanted, would I take it? I took it.

The machine arrived and it was a BT40 machine but the only thing different was the arm on the side mount tool changer; because the machine had already been crate Haas shipped the CT40 arm and the tech swapped them out at install.

No change to the spindle, no change to the drawbar inside the spindle. As far as I can figure it the only difference between Cat40 and BT40 is the flange that the tool changer grabs.

[Ginger_Ninja54]

We're in the Uk and always use Cat tooling (CT/Din69871).
the difference is the position of the groove for the toolchanger, as already identified.
also, it is only the arm on a vertical toolchanger machine, but on an 'umbrella' toolchanger, all the fingers need to be turned over.
I believe a few years back the fingers were different, and you needed seperate ones, but they are now made to suit both types, the offset spacer is on them all.



the pullstuds are a different length to compensate the thickness of the flange of the differing tool types.

[l u k e]

Thanks for the info everyone...

[CarbideBob]

My understanding of the difference is that one is english thread the other metric. Cat holder standards were originated by the Caterpillar company here in the states. BT holders were a metric variation of this original design.
The distance to the flange should make no difference as neither of these designs locate on the flange. This is a characteristic of HSK holders which is way they cost so much more.
Bob