For small square sections, say less than 5mm, filing the flat is quite a quick operation,
otherwise for a larger square it would be best done on the milling machine. For smaller
sizes and with the jaw mounted in the vice as shown it is easy to measure the thickness
at points along its length with a micrometer and make minor adjustments as is found
necessary. Sketch2 shows how the thickness of the jaw is calculated.
When milling the jaws as shown in photograph 6 measuring the thickness is easily
done with a depth micrometer across the two jaws and measuring to the parallel on
which they are resting.
In the case of the first set of jaws that were parted off these must be returned
to the collet chuck and gripping a length of square material so the front of the
collet can then be faced and the head lightly chamfered and with that done the jaws
are complete. If you do not have an application for the second set then these can
be held in reserve until a use surfaces. If you anticipate eventually needing a
number of sizes another double sets of blanks could be made for subsequent use whilst
set up for the process. The whole process is quick and if making a number of sets
then a half an hour per set maximum would be about the time taken.
Of course, the same size round collet need not be used in every case and a smaller
size with smaller square section material for the jaws can be used when sizes of
3, 4, or 5mm square are being held.
If you use the ER range of collets these jaws will give you a facility which is not
available commercially and even in the case of 5C collets the hassle of locating
a supplier and placing the order will no doubt be as time consuming as making a set,
added to that is the bonus of a financial saving.
Being soft, jaws can easily be modified at a later date to take larger section material
rather than making new jaws completely from scratch. This being another plus.
Round and Hexagonal
If an urgent need arises for a round collet that you do not have then a set could
easily be bored out providing the card packing was still intact. You may even be
able to take three pieces of hexagon bar and assemble them with card packing and
make collet jaws to hold hexagonal material on just three sides. I think though that
it would be advisable to mill a flat on one corner of each bar for the three jaw
chuck to grip.