side mill a bit of scrap with the drawbar loose and nothing under the nose

Unless it's welded in, it should drop out

edit: and make sure the "drop" distance under the nose is only about 1mm

Edited By Ady1 on 30/05/2023 10:24:31

Hello Trevor,

Sorry to hear of your difficulty. I don't know the mill but I assume it is a vertical, not horizontal. If you have a lathe as well you might try to make a jack to force the collet chuck to release, I don't think it will have cold welded into place.

Unscrew the closing nut for the collet chuck and put a close fitting 8 mm plate behind it having two threaded holes for jacking screws to bear on a solid part of the machine somewhere behind the chuck. Refit the chuck closing nut to grip the plate and use the two screws to apply load to the plate.

Add heat with a hot air gun as you have done previously above the chuck and belt the drawbar end to apply shock from time to time. Leave it a while, add turns equally to the jacking screws and leave a thick rag below it to protect the table while you go off to have a cup of tea. It will come out I promise!

Moral. Don't leave assembled with the drawbar pulled up tight after use, take time to strip down and put things away in future.

Regards Brian

Hi Trevor, please be wary of using a hammer to assist with taper removal it may damage the bearings ! Remember these are small machines and not to industrial spec, it is common practice to use this method in industry but these machines are fitted with different tapers that break much easier and of course the bearings are far more robust.

There was an extensive post on groups.io relating to this problem and after much perseverance the problem was solved — a load read but lots of ideas https://groups.io/g/emcoV10lathe/topic/94147274#22906

John

Patience and persistence.

5 tactics available:

• Tapping the drawbar sharply with a hammer applies a peak shock pressure to the joint that's likely to unlock it. When the taper is normally tight, tapping the drawbar with a hammer is unlikely to damage the bearings. Folk worry it might, but I've never seen a report of actual damage, and the method has been in use for about 160 years. I think most of the shock energy in the blow is absorbed by releasing the taper, and has little impact on the bearings. Pounding on a jambed taper is ill-advised!
• Soaking in penetrating oil. This helps if the cause is corrosion or gummed up oil sticking the taper together.
• Heat is effective against corrosion, gummed up oil, and a tightly wedged taper. It works by expanding the metal on the outside of the joint faster than the inside. Simply blasting the whole lot with a torch and keeping it hot is more stressful than quickly heating the outer to sizzling hot (a little above 100°C) and then letting the whole thing cool down for an hour, less if cooling is available, repeat several times. Each hot/cold cycle moves the joint slightly and it will eventually give. You might speed the process by giving the slightly loosened drawbar a couple of sharp taps with a hammer immediately after the torch is switched off. Heat and shock together,
• Wedging applies a steady pressure which is kind to the bearings but has little shock effect. I use two slotted wedges sliding over each other from opposite sides to release drill chucks. One wedge is supported with a lump hammer whilst the other is banged home with a small one.
• Ady's sideways cutting method has worked well for me. Set the mill up to take a heavyish interrupted cut into some awkward scrap. Undo the drawbar. Side-cutting with more than normal vibration and chatter is good at undoing taper joints.

In the absence of corrosion or gummed/caramelised oil, the most likely cause of a serious jamb is putting a cold taper into a hot socket and then over-tightening the drawbar. When the hot socket cools, the resulting shrink fit is super-tight, even after the drawbar is undone. Even worse when in place long enough for a little corrosion to take place as well. Or for the oil to gum up. (3 in 1 isn't a good choice on tapers..)

Dave

Edited By SillyOldDuffer on 30/05/2023 12:37:36

Edited By SillyOldDuffer on 30/05/2023 12:38:42

It sounds like you have the best-possible fit of male and female tapers

… Noting, of course, that Morse taper is designated ‘self holding’

I can only suggest that a much bigger temperature differential is required

Warm the outside as much as you dare, then apply liquid nitrogen to the male [collet chuck] and act swiftly with that hammer.

MichaelG.

Edited By Michael Gilligan on 30/05/2023 16:07:23

Rather than heat anything where the bearing temperature is the limitation, a running bearing shouldn't go much above 60 deg C, try applying a cooling liquid up into the bore of the holder, something like a pipe freezer liquid. The severe alternative would be to lower the head so the spindle itself is resting on metal, put as large a diameter bar into the spindle from the top and hit it with a solid hammer, don't pussy foot with a lead hammer you need a good sudden impact blow to break the taper.

Isn't hitting the draw bar top etc going to ruin the bearings, unless the spindle bottom is carefully supported?

Tony

My old Emco miller gets collet and drill chucks stuck quite often, I use a thin rod that fits inside the internal drawbar thread on my machine, then tapping it with a hammer cannot damage the thread as possibly would hitting the drawbar directly

As Michael said, you may have the perfect fit, even if you dont want it !

You are not alone, I had a somewhat similar experience some years ago with a tapping unit which fitted into my milling machine spindle, using a morse taper sleeve.

Problem was, it fitted too well to the sleeve ! Got the unit free of the spindle OK, but no way could I remove the sleeve, which I needed for another job. Tried everything I could think of, and in the end the only way that worked was to make up a holder to support it and use a flypress to press it out. Lucky enough the sleeve was open end.

No use to you I know, but these things can really bond to each other

I had a similar experience with a MT2 reducer stuck fast in the MT3 socket of a Chester 626 mill. (I posted a thread on it a couple of years back). I couldn't knock it out as the internal bore meant anything I passed through the spindle just passed through the reducer. I tried heating it, freezing it, vibrating it etc to no avail. In the end I had to remove the entire spindle and take it to a local engineering firm who tig welded the end of the reducer so it could be knocked out from the rear. It came out easily, quite possibly because of the extreme heat of the welding process. A bit extreme, no doubt, but no damage caused and the mill still working fine to this day.

That's one way of applying heat internally

put a bit of metal into the collet chuck and weld it up to a very hot state, you'd need to protect the mill table with a fire blanket and a bit of board