get mine off ebay

I may be totally confused but I think that the OP is looking for a 3MT arbour with a male 1/2" x 20 unf thread on the big end and a female drawbar thread (any size) on the taper end.

ARCeuro blank end arbours are pretty tough but I managed to make an arbour for gear cutters out of one. My guess is that the big end could be softened by heating to red with a gas torch and allowing it to cool naturally. Threading the end would then be a bit easier.  Try it with the blank end arbour you've already had a go at.

HTH

Rod

Edit: cross posting:  cutting off the tang and heating the taper end will tend to soften , not harden

Edited By Roderick Jenkins on 03/08/2015 20:45:15

> If I do ever find another 3mt with a blank end I d be reluctant to buy it as having been assured by the company it was machinable I wonder how many more I could end up buying

Usually it's only the blank end that's machinable – did you ask if the taper was soft?

If you are content with the taper being from a easily machinable steel, yhy not make your own?

Neil

Even Amazon UK sell them

BC2 – sorry, never quite know peoples abilities on here.

OK, here's my final suggestion. I've used blank arbors where I've needed larger diameter material on them than the 'head' supplied (such as slitting saw holders and small faceplates – that kind of thing). I've generally turned the existing blank down to make sure it's true and then loctited the new piece on. But I've also frequently had to drill them too. In your case you need a narrow head but I don't see why something similar wouldn't work.

Couldn't you cut off the existing 'blank' bit and then drill into the taper's core an inch or two. You could then add a new (free machining) head – either by tapping the hole and screwing it on or simply by Loctiting and pinning it in. True the new head piece up and then screw cut it. In fact if you have a "spoiled" MT3 taper already – this may be a good one to try this approach on.

IanT