After giving up all hope of finding an 8mm Boley style 8mm collet / arbor with a 5/8" x 11 TPI thread for mounting an Emco chuck, I decided to have a go at making one. The following was how I went about it.

First of all I chucked a pice of 1" steel bar into the chuck and made sure it was well gripped. Faced off the end and put a centre in it, cleaned up the bar down to the finished diameter of the 'backplate', turned to size the chuck register boss and screwcut the 5/8" x 11Tpi thread on the end – checked it against the chuck thread.

Next operations were to turn the 8mm finished size of the collet and 20degree taper. Finally drilled through the full length of the collet with a pilot drill.

After parting off, placed a bit of scrap Al alloy in the chuck, faced off, bored a recess to accept the chuck register on the part machined collet then screwcut 5/8" x 11Tpi through the centre. Next mounted the part machined collet into the Alloy bar.

With the collet running true, the threaded end was turned down to 7mm and a 40 tpi thread cut using a 40tpi chaser, checking thread against the lathe drawbar. Final operations were done on the mill to cut the keyway and put a couple of spanner flats onto the 'backplate' .

Finished 8mm collet / arbor.

Finally, the chuck mounted onto the lathe showing the manufacture of a broach in 5/32" silver steel to be used in making a steam injector for an LBSC Speedy.