Bridgeport Interact power drawbar and toolholder question

[richardb15]

Hi all,

I know this isn't strictly about the Acorn but I couldn't see another place to ask this question. I've got the Bridgeport Interact 4 Series 2 and it has the factory power drawbar option. This uses a hydraulic piston above the drawbar to push down the drawbar against a stack of belleville washers. I got this machine with no toolholders and my previous machines have used pull stud type toolholders, so I'm in new territory here. Its a 40 size taper spindle.

So I don't know what type toolholders fit this machine, or how the drawbar is supposed to lock them in. The manual is not helpful for this, it only references the manual QC setup. I've taken the drawbar out and expected to find a collet type lock, but its just a plain head like a cap head bolt. Can anyone help with this, am I missing bits, or what type toolholders should fit?

Pics here below, and extracts from the instruction manual ref the drawbar, but unfortunately the quality is very poor, especially the section view.... but I think it looks like a CAT40 toolholder?

Drawbar lower end:


Full drawbar out of spindle:


Drawbar hyd cylinder on top of spindle:


manual extracted pages:


Any info or advice appreciated!

EDIT: better res PDF added

[richardb15]

I did find this same machine for sale complete with a photo showing some tooling with the pull studs, but from zooming in it looks like two different pull stud lengths are on the machine bed, so that does not really help much

https://www.simmomach.co.uk/used_machin ... p?pid=1261

[Chaz]

The earlier Interacts were all Erikson QC30. Basically this -

Could it be the same?

[richardb15]

The QC30 were the manual drawbar version toolholders, but the hydraulic piston power drawbar ones are different as the drawbar does not rotate to unscrew/tighten, so can't hold threaded toolholders.

I've never owned a non air rachet powered drawbar machine, but having done a load of googling I'm wondering if mine should have a BT40 petal/spring setup around the end of that drawbar stud, and the petals are missing?

[richardb15]

Should it have something like this on the lower end of the drawbar?

[Chaz]

BT40 petal clamp ebay listing.PNG

Should it have something like this on the lower end of the drawbar?

Ah ye, could be. Ive actually looked at converting mine but I dont have clearance for 'petals' that can hold.

[richardb15]

I figured the only way around this was to reverse engineer the spindle, pull studs and toolholders into CAD and see what looks like would work. The section here shows the spindle in blue, a BT40 toolholder in purple, petal arms in grey, BT40 pul stud in green and the drawbar bolt in orange.

Released (down) position

Locked (up) position

So it seems the BT40 petal thing is right as the bottom edge of the petals are correctly positioned to move in and out of the release diameter, but the pull stud is about 3mm too long as it touches the centre bolt and it shouldn't. That is with the shorter BT40 toolholder, the CAT40 are taller still so make the problem worse. CAT pull studs are much shorter so no good either. I guess I might end up making my own pull studs to get this sorted, probably quicker than trawling through the hundreds of different types available.

I'll order a couple of BT40 toolholders (all my ISO40 tooling has the parallel collar for threaded drawbar use, won't fit the Bridgeport ) and the BT40 petal pull claw and see where that gets me. I hope if nothing else this thread will act as a future reference for anyone else trying to get one of these machines sorted!

[Chaz]

Great, thanks for that. Hopefully it works, if not, we have all learnt something.

[cncsnw]

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.

[WesM]

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?