Help! Bridgeport VMC 800 drawbar removal?

Hi guys, hoping someone can offer some advice!

Have been looking at this drawbar today as the run out is getting worse and you can easilly pry between the spindle nose and tool holder flange, which seems to indicate the pulling force is pretty weak.

This drawbar arrangement seems different to others, looks like it has to come out of the top. I have attached a drawing.

I undid the top nut (7) and removed the actuator sleeve (6), but all you are left with is the top of the drawbar.

This is flanged at the top to push down on the washer stack, so can't be withdrawn from the bottom.

There is a 5mm hex up inside the spindle from underneath, which attaches the ball collet to the drawbar - but trying to undo this is just turning the drawbar. Unfortunately there is nothing to hold onto on top of drawbar

So I put it all back together and operated the air/oil actuator to put some pressure on the drawbar in the hope it would stop it from turning.

Holding the unclamp button, the locking screw (14) now has some resistance, but it is very very tight.

So tight i'm worried it will ring off.

So before I carry on and give it some more stick, has anyone had these type of drawbar apart before? Am I on the right track?

Any chance the collet lock screw could be LH thread??

Really appreciate some help - thanks!

Replying to this thread for anyone who may be asking the same questions in the future!

As I suspected, in this design the drawbar is removed from the top of the spindle.

To do this, first you need to loosen the 'special locking screw #14' - this is a 5mm hex screw up inside the collet. I had to operate the spindle unclamp cylinder to put pressure on the drawbar to stop the drawbar from spinning whilst trying to turn the screw - with a healthy drawbar you may not need to do this.

The locking screw was fairly tight, but just needs a good crack with a decent sized bar/ratchet to free it off (I used a 5mm long reach hex - 3/8" drive, but you could use a long T-bar).
This screw is used to lock the position of the collet relative to the drawbar, so once this screw has been loosened, you then need to wind the collet off of the drawbar. There are two slots in the collet, use these to wind off the collet whilst holding the spindle still (again, if the drawbar spins you may need to actuate the unclamp cylinder). Withdraw the collet taking care not to lose the ball bearings. When the collet is refitted it should be fitted with 79.5mm between the spindle nose and collet nose when in the clamped position (without tool).

With the collet removed you can then remove the drawbar actuator cylinder from the top of the spindle. Once this is out of the way you need to remove the 'Spindle End Cap #7'. The spindle end cap has threaded holes all around it (perhaps for balancing), I fitted some bolts into these holes and used a suitable collet spanner to undo it. This was quite tight, I had to clamp the spindle tool drive dog in a vice to be able loosen the top cap. Once this is removed you can remove the 'Actuating sleeve #6'.

Now you will see the top of the drawbar. The drawbar needs to be pushed out from underneath. I used a long 1/2" extension bar to drive the drawbar up and out of the spindle - a brass or aluminium drift would be best, but this one wasn't too tight, and I didn't have a suitable soft drift to hand.

Once out you will see a the preload nut at the bottom of the drawbar, measure the distance of this nut from the end of the shaft so you can preload the new washer stack when reassembling.

And re-assembly should be reversal of removal

Our machine was showing runout on any tool or tool holder, but none on the spindle taper. When I removed the drawbar 50% of the washers were obliterated, and a good 50% of the remainder were cracked.

Hope this helps anyone who may need the info in the future!