Thread: Removing seized mt2 chuck from spindle

Hi,

I am attempting to remove a seized collet chuck from a small milling machine spindle.

Hitting the draw bar has done nothing and even soaking in penetrating oil yielded no results.

The spindle has been taken apart and there are no signs of any pins which would be holding the chuck inside.

If I was to heat the spindle with a propane torch or using a small oven, what temperature would be recommended and what possible actions would maximise the chances of the chuck letting go.

Originally Posted by ml018

Hi,

I am attempting to remove a seized collet chuck from a small milling machine spindle.

Hitting the draw bar has done nothing and even soaking in penetrating oil yielded no results.

The spindle has been taken apart and there are no signs of any pins which would be holding the chuck inside.

If I was to heat the spindle with a propane torch or using a small oven, what temperature would be recommended and what possible actions would maximise the chances of the chuck letting go.

I used a hot air gun with 650ºC max temp to remove an MT3 arbor from a mill.
You might need to cycle it a up and down a few times.

If you have stripped the spindle and there are no bearings that can get damaged, I would drop a round of brass bar turned to fit in the bore, then a length of steel bar on top of that, give it a smack with a hammer and it should just pop out.

I assume that there isn't a slot in the spindle for a taper key.

If the spindle taken apart means it is out of the machine use a press.

No there is no slot for a drift.
I have heated the spindle in a small oven at around 250 degrees C and gave the drawbar a few wacks with a hammer but nothing happened.
After 3 failed attempts I have decided to place the entire spindle into kerosene to allow it to penetrate and dissolve some of the grease/oils between the 2 stuck faces.
There is a very tiny gap on the exterior face of the taper where it might hopefully get a little deeper.

As for the idea with the press, I do not have one, It would be hard to clamp the piece down (odd shape with the stuck collet chuck) and if something goes wrong, I risk bending the spindle.

Originally Posted by ml018

No there is no slot for a drift.
I have heated the spindle in a small oven at around 250 degrees C and gave the drawbar a few wacks with a hammer but nothing happened. .

250º is not going to do much.

Originally Posted by BobL

250º is not going to do much.

How much would be ideal?

Originally Posted by ml018

How much would be ideal?

As much as you get get but obviously not melt the thing or disrupt any hardness properties but as its a fairly large lump of metal a relatively long time will be needed to do that.
I'd try a propane torch for a 3-5 minutes and see what happens.

In order to loosen the internal part, you must get the heat into the outer as quickly as possible. Ovens and heat guns are next to useless for this as they just don't have the "horsepower" to get the heat in quickly enough. Oxy acetylene or Oxy propane with large heating tips will be much better choices if you can find them. The idea is to heat the outer, while keeping the outer as cool as possible, the outer expands and loosens its grip on the inner section.

Wacking the top of the drawbar is not going to do the threads on either part any good ! This is why I suggested what I did.
As suggested above you need to get heat into the outer section as quickly as possible, before the heat has time to penetrate to the taper.

Part of the problem with Morse tapers is the length of the taper, they are very long with respect to the diameter and can effectively weld into the socket, particularly if they are not kept clean !

One other thing, you say that the taper is holding a chuck, if it is a screw on type it would help to remove it, or it could be on a taper of its own, in which case a pair of chuck removal wedges might release the chuck. Either way it would reduce the amount of metal to absorb heat and reduce the inertia.

Im with pipeclay on this. Its out of the machine, put it in a press. Any local engineering firm will do it for a very small cost, its but a few minutes work.

Heating it to 650°C is waaay into tempering tempertures. If that spindle is hardened, youll be modifying its properties with temperatures up there. I absolutely would not be doing that without having exhausted the press options first.

Can you slide a suitable length of thick walled tube or a spacer over the collet chuck so that it sits against the spindle and tighten the collet nut firmly agianst the spacer to act as a puller, then hamner the drawbar.
shed

On a sample size of one, you could try "Loctite Freeze & Release Penetrating Oil".
A mate bought an MT3 taper pillar drill with an ejection slot. We gave the drift a fair belting and the chuck stayed put. We gave it a spray and it damn near dropped out by itself.

Originally Posted by scottyd

Im with pipeclay on this. Its out of the machine, put it in a press. Any local engineering firm will do it for a very small cost, its but a few minutes work.

Heating it to 650°C is waaay into tempering tempertures. If that spindle is hardened, youll be modifying its properties with temperatures up there. I absolutely would not be doing that without having exhausted the press options first.

Tempering not only requires heat but time - a lump of metal that size can take 1000º for a few minutes with minimal changes in temper mainly because it won't get to 1000º during that time and be at that temperature for long enough.

Need to get a bigger hammer I think. 10lb would be a start.