In other news:
I've been meaning to measure the runout on my drill press for a while, and having nothing better to do this afternoon finally got around to it. (I was prompted by the nice non circular holes that my Dremel was making the other day. Different drill obviously, but it reminded me that I ought to get around to measuring the drill press proper.) Chucked up a bit of precision ground rod and got the dial gauge out. Result: 90 microns, 90 bloody microns! (That's about 3 1/2 thou for those still using measurements based on King John's foot). 'orrible.
But I got a nice surprise to go with the nasty one. I drifted the chuck off and measured the (circular) runout of the mounting taper. I couldn't. With a 10 micron/division dial gauge (Mitutoyo, naturally) the needle just wavered. So I haven't put the chuck back on. Now got an order in for an ER20 collet holder with a B16 taper and a set of ER20 collets (all 8 micron runout class). So, an idle "I really ought to get around to that" has set me back the best part of £100, just so's I can get proper round holes. Oh well.
The chuck probably ought to go in the bin, but will probably sit in the back of my tool chest gathering dust "just in case".