More messing with my Unimat SL.

One problem that I've noted is that the drill chuck runs out of true when fitted to the headstock spindle, which would cause a lot of trouble when using the machine as a mill/drill. The back face of the chuck needs to butt up against the shoulder of the spindle for it to run true, but the thread inside the chuck body bottoms out onto the spindle thread before the back face meets the shoulder, leaving a gap;

The proper solution would be to machine away part of the chuck thread, but I decided instead to turn a brass collar to sit between chuck and spindle shoulder. Mounting the drill chuck in a 3 jaw is possible, but I'd need to clock it up (make sure that it runs true using a dial test indicator (DTI)) and all of my DTIs are down at my Mum's house in Bedfordshire along with a lot of other usefull tools. And anyway, I fancied making something...

I turned a spacer from 16mm dia. brass, boring it out to 12.1mm dia. then parting it off 2mm long. The boring bar that I have is too big for the job, necessitating mounting it above centre height to clear the bottom of the bar inside the bore, something that I could get away with in an unimportant bore in brass but wouldn't have liked to do inside the drill chuck. The only important part of the job was to make sure that the two faces are parallel, but facing the front of the job then parting it off achieves that.
The spacer being parted off;

Note the Allen key, unlike a lot of larger hobby lathes the saddle of the Unimat can be locked in place (as can the cross slide), handy when parting off.
The spacer in place;

 

Fitting the spacer now means that the drill chuck runs true with no discernable wobble (although ideally I'd like to check it with a DTI).

Paul.