Repetitive taps on opposing sides with a hammer; doesn't need to be hard but you may need a lot of taps. Repetitive, and oscillatory, side loads are a classic way of loosening a taper. Which is why it isn't recommended to mill without a drawbar.

Andrew

You could use a pneumatic drill to "hammer" it out using a lot of small taps. Preferred

The thread on the collet (M40x1.5) and the collet nut can be used to make a puller against the shoulder of the mill.

With my Chester Lux mill R8 taper, when changing tooling I use my air impact wrench which undoes the draw bar, (not overly tightly secured) and and loosens the taper. Place something to catch the ejected tooling safely – ask me how i know!

Robert Butler

Edited By Robert Butler on 16/08/2022 23:09:30

Short length of tube which bears on the face of the quill, the other end of which bears on the back face of the collet nut. Tighten the nut while holding the spindle to squeeze the tube up onto the quill – pulls the taper down.

If the OD of the collet thread is bigger than the OD of the quill, slip the/a spanner in between the tube and the quill to provide a bearing surface.

I don't think that P R was suggesting running without bthe drawbar. merely slackening, to finger tight and taking a few cuts at low speed is likely to shake things loose.

If you did not want it to, it WILL happen.

Probably, the ER collet chuck was inserted, cold into a warm quill.

DON'T do that.!

If you choose to go for the method of using either wedges or packing behind the 40 x 1.5 mm collet clamping nut, to try to extract the chuck, having the drawbar slightly loose, and giving it a bash once the load has been applied, MIGHT break the taper loose.

If the taper moves even slightly, you have succeeded!

Howard

side milling with a slot drill type cutter, leave a tiny gap and it drops down safe

better than battering the snot out of it

Correct I was not suggesting milling without a drawbar, just a loosened one.

I had the exact same problem with a 3-2MT reducer stuck in the quill of a Chester 626 mill. There is a thread on here somewhere but to summerise, I couldn't knock it out from above as there was no shoulder, it wasn't threaded so I couldn't use the drawbar. I couldn't vibrate or twist it out. Gentle heat had no effect and I used a can of freeze spray which also had no effect.

I ended up removing the quill and taking it to a small local engineering company. They tig welded the protruding part of the reducer to facilitate knocking it out from above. Whilst still warm from the welding it came out with a gentle tap.

The mill has been in use ever since and has not suffered any ill effects.

Likely causes one of more of:

• Cold chuck inserted into a hot taper causing an extra tight grip as the temperatures equalise
• Drawbar over tightened in the past, perhaps because the tapers are scored, galled or worn
• Chuck left in place for a long time allowing oil to gum or corrosion to develop.

Heat, penetrating oil, sharp tapping (avoids pounding) and vibration all tend to loosen tapers.

Sharply tapping the drawbar hasn't worked. Penetrating oil left to soak for a few days might help if the cause is gum or corrosion, but it may be difficult to apply to the joint and it removes lube from any bearings it gets into.

Vibration is good at loosening stuck joints and I'd try it first. Normally, mills are set up and used to minimise vibration, but in this case I'd do it all wrong. It's somewhat risky so keep clear of the cutter, wear eye protection, and be ready to stop. As this is off the beaten track I hope others will comment on the following suggestions:

• Loosen the drawbar
• Reduce rigidity by lifting the head as high as possible and fully extending the quill
• Reduce rigidity by holding a longish bar in a vice such that the cutter engages the protruding end
• Leave all the slide locks off.
• If you have one, use a long blunt HSS cutter. The cutter is likely to be spoiled.
• Take a series of cuts along the edge of the bar, adjusting rpm, feed rate and depth of cut to maximise vibration (chatter). The exact settings vary with the material and cutter, but the cut direction should be misaligned with the grip of the vice so the material isn't well supported in the direction of the cut. Climb milling usually causes the most vibration on small mills but try cutting in both directions.
• Might be wrong but I don't think bumping the cutter into the material is a good idea because the cutter might break. I also think protracted vibration is more likely to break a stuck taper than a few thumps.
• Stop immediately the joint comes loose – spinning two tapers quickly damages both of them.

Heat is almost guaranteed to work but it may be difficult to apply without dismantling the mill. Although heat is the Queen of dismantling methods I'd try vibration first because it's easier to do.

Heating the spindle, not the chuck, expands the spindle and tends to loosen the joint whatever is holding it together.

I think many repeated cycles of moderate heat and cooling are safer than one blast of severe heat. By moderate heat I mean a temperature below anything likely to alter the temper of the steel, say 100 to 200°C, below the temperatures that cause oxide colours to appear, and definitely not glowing! If an expert says disagrees, believe him not me.

Final advice. This sort of problem causes me to lose my rag and reach for a sledge-hammer. Resist the temptation to take extreme measures – slow but sure is unlikely to break anything

Dave

PS After posting I see others recommending wedges.  Good idea, and you can make them in the mill.  Making a wedge with a slack drawbar might be enough!

Edited By SillyOldDuffer on 17/08/2022 09:31:02

Try a bucket of ice on the table with the chuck inserted until the chuck is cold then hit from the top and or sides

Have used this myself and it certainly does work.

Repetitive taps on tapered part works as well. As already stated no need to beat the living daylights out of it as that will cause damage.

You will be surprised at what I have had to do in the plant hire business after some idiotic builder has their hands on the machines.

Even when they report that a machine will not start and when I arrived on site the cause was they had lost the starting handle.