I think that in some circumstances relieving the centre of a less-than-perfect taper shank (as is sometimes seen on commercial items) may actually improve its grip.

I only ever nip up my drawbar by hand and, when this is not in use, use and recommend the Facom versions of Jason's expanding wedge which avoids the need for a third hand!

Chris,

If you mean THIS EXAMPLE then, no, it won't do what you want. You would need to get a sleeve to reduce your MT4 to MT3 or 2 then fit an ER32 collet chuck with matching MT into that. You would still be stuck with how to remove the sleeve. You would be far better off, in my opinion, to obtain an ER32 collet chuck on an MT4 taper shank. Like this:

Then you're back to square one with the extraction problem! Though it shouldn't be a problem if you do it correctly.

Easy for me to say, he said smugly, as an R8 user!

John

Do you mean one of these, as sold by ArcEuro?

If so, it's no good to you. It's a reducer – a big MT taper on the outside, with a smaller MT taper inside. For example, a reducer with an MT4 outer an MT2 inner allows MT2 tooling to be plugged into an MT4 spindle. The MT2 tooling is secured and released in the usual way with a drawbar. The Release Nut pulls the reducer out.

What exactly is the problem you're trying to solve? MT works quite well. Three reasons why it might be difficult to eject an MT taper:

• The drawbar was overtightened by the operator. (Some chaps can't resist heaving on spanners and then whacking them extra tight with a hammer. Don't! ) I find hand-tight plus a 1/3 turn about right. Experiment to find out what works on your machine. It's a balance – enough tension to stop the taper slipping during a cut, but not enough to wedge the taper so tight a short sharp tap on the drawbar undone 5 or 6 turns won't release it. Note 'short sharp' – never pound on a drawbar!
• An accidental super-tight shrink fit was created by inserting a below room temperature male into a hot female spindle and allowing the pair to cool. Avoid by warming the male before insertion or letting the mill cool down. To release a shrink fit it may be necessary to quickly warm the spindle with a gentle flame before applying a sharp tap, or wedges.
• The tapers corroded together or are glued together by ancient oil turned into varnish. Dribble penetrating oil down the drawbar and leave overnight, if that doesn't work warm the spindle and/or wedge as above. Several heat cycles may be necessary. Avoid by sensible maintenance – don't leave taper tools stuck together for a long time.

In my experience appropriately tightened clean tapers release without bother. The sharp tap needed doesn't worry me: in theory it might damage the bearings, in practice it doesn't. (Pounding on jambed tapers is a different story.)

As per NDIY I use an MT / ER32 collet chuck most of the time on my mill, occasionally swapping it for a fly-cutter, boring head, drill chuck or circular saw. None of them slip or refuse to release and not much violence is needed.

Copper headed hammers are recommended for applying the sharp tap but I use an ordinary hammer with a home-made aluminium disc on a handle interposed to protect the drawbar head.

MT is the original quick release system. It's still popular after well over a century. There are better quick release systems, but I suggest MT is fine for amateur purposes. I don't feel any need to modify it on an 1100W mill.

Dave

Having a MT4 spindle has the advantage of being equivalent to R8 in stiffness, but there is not as much tooling about. The er32 collet set would be very useful and would not need changing often except for drill chucks and shell mills. As I said earlier, there could be a possibility of adding a captive drawbar, some are held at the top of the spindle and others like mine are utilising an internal step in the lower part of the spindle bore just above the upper part of the tooling.

With the right lathe and carbide single point threading, the OD of the er32 could be threaded ok, but the extractor would interfere with the spanner flats. Perhaps a sleeve could be fitted to the er holder which had spanner flats at the lower part and threads at the top. It would have to be short enough to leave a gap between it and the spindle nose and be smaller diameter than the nose for a nut to work. Some measuring would be required before any metal was cut.

 This is the way I made a captive drawbar as there was room inside the spindle to do so.

Edited By old mart on 06/12/2021 18:45:00