Hi Frank

I have the exact same high speed head as you.

If you PM me with ur e-mail address, I will send you an original drawing of the collets, they are as you say very difficult to come by.

I managed to get full sets of metric and imperial, but it took two years to find them and some of the metric ones could do with changing for better ones.

I just hope if any do come up on ebay, that I see them first.

Just be careful you do not make the mistake of buying the ones available new that are described as 16mm collets, they look the same but the thread is subtely different and they do not fit the head.

Dont ask how I know this !!

You only really need to get a few sizes that will cover the common milling cutter diameters, ie

6,10 & 12mm and 1/4", 3/8" & 1/2", then just fit a small chuck on a plain 1/2" shank to use drills.

Phil

The RC machine ones DO NOT FIT the high speed head drawbar thread.

Phil