I have though made many items that would normally be hardened and used them over
many years in the unhardened state without any problem, that is of course with the
limited use items get in the average home workshop. Because of this I feel that the
thread and the 30° face used to close the collet should be perfectly OK. I do though
have some reservations regarding the flange that is used to jack the collet out of
the body when being undone. If therefore you fancy the challenge then the following
is my untried idea as to how its manufacture should proceed.
Place a piece of 50 mm steel in the four jaw and set to run reasonably true. Bore
through 26 mm diameter then at 38.10mm for making the 1.5mm pitch thread. Next make
the 1.5mm grove to a diameter of 38mm diameter. This will be 6mm deep at this stage
so you will need a very special grooving tool. Follow this by making the internal
Using the four jaw, now set the ring over by 1.5 mm (3mm total indicator reading)
and bore the flange to 32.5mm. Remove the ring and chuck from the lathe and once
more fit the collet body, again paying attention to the cleanliness of the mating
surfaces. Fit the closing ring and having set the top slide to 30 degrees bore to
27mm, also finish the front face including chamfer. Machine the six groves and make
a wrench and the job is done.
Having completed the parts required you now have a very useful addition to your lathe
being able to grip any diameter from 2mm up to 20mm. Being used at predominantly
smaller diameters where high speeds are necessary, using a collet chuck, Photograph
8, is much more pleasant than using a jawed chuck. Another advantage is that the
collet chuck should be more accurate than its three jaw counterpart.