Just a quick update on this one..... So, I set my topslide over to measure 0.050" per inch to cut the taper, cut the taper which came out very nicely thank you (lovely smooth finish on the ali). And, as some of you will have already realised.... at completely the wrong taper of 0.1" per inch!!!

Then I had a 2 week holiday.

Having a spare few minutes the other day... I tried my new taper out & discovered my glaring error. So, back to the topslide, re-set for half the previous angle, as measured with a DTI on some freshly squared up stock. Cut the new taper, crossed fingers & clenched backside, removed the chuck, cleaned out the spindle tube & popped the freshly cut aluminium taper jobby into the spindle. A sharp tap with the plastic hammer seated it beautifully, hurrah! In fact, it took some fairly hefty beating on the back face to get it back OUT of the spindle!

I blued the spindle with some Stuart's Micrometer Blue, and popped it in again. And when I did finally managed to smack it out, it looks like it's contacting all the way around for a good 2", so I'm going to call that "good".

Whacked it in again, faced it & turned down the outer diameter so it's running true, and drilled a 1/2" through hole (I'll open that up a bit further yet), but this leads to my next question!

What's the best way to cut a decently accurate internal Morse Taper (#3 for what it's worth)? The idea is this sleeve will convert my spindle to MT3, so I can mount my ER32 collet chuck, ideal for holding smaller stock, and hopefully a tad more accurate than my 3-jaw chuck. In fact, I'm hoping it'll prove that the part wobble/unconcentricity I seem to suffer from all the time IS in the knackered old 2nd hand chucks I've got, which will persuade me to part with some hard-earned & buy a new chuck...