removing Clarkson chuck from mill

OK, we have the Tom Senior mill at school with the vertical S type head and a Clarkson chuck fitted. How the heck do we remove the Clarkson chuck? Tried today by loosening the drawbar bolt and tapping to release any taper that may be in the spindle (MT3 or R8?). Tried several times without any movement at all.
HELP, what do we try next - a bigger hammer? oxy-acetylene cutting torch :-). Anyone done this and knows THE WAY? All reasonable suggestions will be read and heeded.
TIA, Mike in BC

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Bigger copper hammer. Don't be tempted by oxy
Charles

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The reason for the sticking is often that the chuck was fitted when the spindle was warm and the chuck cold, the spindle has now shrunk onto the chuck. the way to deal with this is to get them both warm with, say, a hot air gun and then cool the chuck with ice or a more scientific method like dry ice or notrogen, and the get the hammer out.
Peter

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Michael I think you will find that the damping ring on the Clarkson has a left handed thread. The way to remove the chuck is to put a thin flat open ended spanner on the two flats that are on the end of the spindle, the bit between the Clarkson and the machine. This stops rotation while you use another larger open ended spanner to wind the damping ring up towards the spindle, where your other spanner is. A good tug, and it should "break" the taper away, assuming you remembered to undo the drawbolt. Bob

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Michael Further to my last post, I forgot to mention that if your Clarkson is the newer version there most likely wont be spanner flats on the damping ring, but holes for a Tommy bar. Bob

On Sun, 08 Mar 2009 08:02:32 +0000, Emimec wrote:
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That's the one, holes for a C-spanner. Thanks for all the advice folks. will try again this coming week. Mike in BC

On Sun, 08 Mar 2009 16:10:02 +0000, Michael Gray wrote:
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Yipee! Was in subbing today and found a solid copper 1/2" bar, made a wrench out of 2"x1/8" steel to fit the flat on the spindle, put a pipe on the C-spanner. Loosened drawbar, yarded on pipe, wound dampening ring up as far as she'd go, half a dozen good whacks on the copper bar resting on the drawbar nut and .... BOB'S YOUR UNCLE!! The grease in there was like varnish and took Gunk to loosen that up, so now we have a 2MT spindle ready to accept endmill holders for Weldon shank endmills at much lower cost than the Clarkson type previously needed. Also have one very decorative Clarkson collet chuck ready for the few remaining screw-end endmills left in the box.
Thanks to all who suggested.
Mike in BC