The thing with the holes in is part of the collet chuck. It has a left hand thread (from memory) and is used to increase the stiffness of the whole setup after the morse taper is nipped up. The drawbar (about 3/8" diameter poking out the top of the splined bit) doesn't look right it should be self ejecting. I wouldn't go beating the drawbar with a hammer to get the morse taper apart until you have exhausted other means, you don't want to damage the bearings. There is a useful link at **LINK**

Looks to me also like the square end of the drawbar has sheared off.

If you screw a nut onto the threaded part of the spindle where the draw bar is poking out.

You can use this with a pulley puller to push on the draw bar and hopefully pop the chuck out of its mating taper

This will avoid putting any strain on the spindle bearings.

From memory you will need a 3/4" UNF nut

Dunno what wedges you are thinking of. As I wrote earlier, I use wedges all the time, as the only necessary alternative to a tap on the drawbar with a soft mallet.

I have made my own but they are similar to these:

Wedges

There was a similar debate going on just a few days ago, albeit with a Tom Senior vertical head. Maybe you've already found it, but it's worth looking at

Tom Senior V Head stuck MT2

The secret to this problem seems to be to preload the taper as much as possible – wedges and/or puller – then give it a sharp whack with a hard hammer. I know that will cause a whole lot of sharp intakes of breath, but don't pat it with a soft hammer, give it a good shock. The weight of the hammer is important – needs to be a sharp crack from a 1 lb hammer or thereabouts. But lots of axial preload first.

If that won't shift it don't beat it to death, it needs some science with hot on the outside and cold on the chuck. Put the whole thing in the freezer, then heat the outer with a paint gun. Then preload it and hit it.

Looks to me that the snugging ring on the back of the chuck is already tight against the end of the spindle. It's a left hand thread, try running it down away from the spindle nose to free it up and get it away from the nose to leave some space for the wedge idea. In that other thread the taper gave way with a smack on the top wedge with the bottom one against something big and heavy as an anvil.

HTH Simon

Edit :  Oops that seems to be the wrong link, sorry.  I'll try to update it before the edit timer runs out, otherwise there will be a correction below.

Edit 2: My apologies.  Try this one for size:  Getting a vertical head ready for use

Edited By Simon Williams 3 on 18/05/2020 21:01:44

Edited By Simon Williams 3 on 18/05/2020 21:04:18

That's a clever captive drawbar design, I like it.

That snugging nut is a left hand thread – so I agree you are turning it correclty to push against the end of the quill, but is it moving? Can you turn that backing nut with your black spanner in the opposite direction at all?

That really looks like it should let go.

You need to move the snugging nut away from the end of the quill to create a space into which you can get a couple of slotted taper wedges between the back of the chuck and the end of the quill.

One of the problems you are fighting is that the drawbar is quite elastic – so you hit the top end but the shockwave dissipates as it travels along the drawbar and is just a bump when it reaches the taper. Introducing wedges as an additional axial urge puts the force exactly where it is needed.

I've made these wedges out of gauge plate, cutting the angle with a sanding disc in the angle grinder then hardening and tempering them afterwards. You only need a very slight angle. You need two opposing each other to get the best effect.- they're not as good as the real thing but needs must.

Keep is posted!

Rgds Simon

Gents, I'm struggling to get a handle on this, so to speak.
As several people have mentioned, that ring with the C spanner holes is on a Left Hand thread.

As such, in order to make it bear against the end of the spindle, the nut must be rotated Anticlockwise, as viewed from the cutter end of the chuck.

Please see the photo below for the correct placement, and turning direction, of the C spanner ( though a better spanner would clearly be advisable ).
I know this is the correct orientation, as I've just used it to release the chuck from the lathe spindle, as per the photo below.

Yes I know it's the wrong C spanner and everything needs a clean, but this was a quick setup on the Warco 720 for illustration purposes.
I set it in the lathe rather than the mill so the spanner stayed in place whilst I took the photo.

I'd suggest that there is only a very small gap between the collar and the spindle end in Avon's case, so there might not be enough space for wedges.

Assuming the nut isn't now jammed on the chuck, through turning in the wrong direction, pre-load the nut hard (with a small hammer) against the spindle end and then try clouting the remaining end of the drawbar with a decent sized hammer.
Perhaps protecting the drawbar's end with a lump of copper or brass might be a good idea (and it would also protect the screw thread on the spindle's end if anything moves.

N.B. even just fitting the chuck to the lathe spindle with just a reasonable rap, it took quite a bit of force on the spanner to remove the chuck in the photo shown above, as the morse taper locked quite well.
I'd suggest that using the nut alone won't be enough axial force to eject the chuck, but the preload might be enough when used with a hammer on the drawbar.

Bill

Edited By peak4 on 20/05/2020 11:47:28