Bridgeport Interact power drawbar and toolholder question

[richardb15]

Pull studs are changeable: not all CAT40 spindles use the same stud geometry, and not all BT40 spindles use the same stud geometry. You need to install pull studs into your tool holders that are compatible with your spindle.

Looking at the manual scans you posted, and the photo that richardb15 posted, it seems likely that the Bridgeport spindle is designed for shorter pull studs.

Often, somewhere in the machine documentation, there will be a dimensional drawing for the required pull studs.

Having looked at some pull stud supplier websites it seems there are hundreds of different types, all different lengths, diameters etc but I've not found any site that has a filter for this machine, its about 45 years old after all. Unfortunately there is no drawing or even a reference to the spec of the toolholder and pull stud spec to suit, it goes into detail for the manual QC30 setup but not the power drawbar optional extra. Agreed it needs compatible toolholders and pull studs, no-one wants a 150mm face mill coming out during a job, I just need to work out what should be correct.

If you have a Bellville stack, like you figured out, its a petal or ball bearing/pull stud arrangement. The only other changer I have seen that is not a BT/CAT/HSK, but still uses a Bellville stack is the tormach setup where it uses a R8 collet as a gripper.

I'm not familiar with the exact setup your machine has, but some of the grippers are captured in the spindle, if you look up into the spindle from below, can you see anything?

Yes the machine has a belleville stack setup. I hadn't thought it could be a ball bearing setup, but the maintenance manual extract seems to reference part 18 as a "lock lever" which I guess is what I'm calling a petal, so likely that is whats missing. Looking up from below into the spindle all that can be seen is the head of the pivot pin, the orange bit in my CAD sketch, and of course the internal profile of the blue spindle.

[Muzzer]

My own conclusion is that your petals are missing. Sounds like an awful medical condition! Possibly this is why the machine was sold on. You might be able to find a replacement spindle and drawbar on ebay of this or another type.

[WesM]

You could try contacting a spindle rebuilder who might be willing to you in the right direction. A quick google came up with a few companies that do rebuilds on Bridgeport spindles. I imagine they would be the ones in the know on something this specific. Might even be able to sell you the parts you need.

[richardb15]

Thanks for the notes, I didn't think of trying to contact spindle rebuilders and second hand parts dealers. I've done a bit of googling and sent a few enquiries off. In the meantime a generic BT40 petal clamp set is on its way from China.

[richardb15]

Two machine tool breakers/spares places got back to be but can't help, but put me on to these guys:
https://www.bptparts.com/

I'm waiting for them to get back to me. Meanwhile, after several cups of tea......

I re-read the drawbar manual pages several times, its hard going as the pages are not in the right order, orientation or very good quality. I realise I've been using the wrong parts list! I know the bits I'm missing are items 18 & 19, but not the lock lever and pin as I thought (sounds plausible right?) but these below:

So it seems the collet setup is an SSK 40 ANSI, and the draw stud is an AZB 40 ANSI. This seems to make sense, as the AZB pull stud is 3mm shorter than the BT40, and I'd said the BT40 was too long from my calcs. There are so many different types of collets and pull studs, what a ridiculous state the CNC industry has got itself into. I guess to make shops stick with one make of machine to make tooling interchangable. Anyway, SSK 40 collets are still available, but range from $400 to over $1000, for instance:
https://amastone.com/shop/ssk-petal-col ... sk-40-ansi

I'll wait for my BT40 collet to arrive and measure it up then decide how to proceed. At least part of the mystery seems to have revealed itself