There remains two flats to be made which can be done as shown in Photograph 9. Note
the small rectangular plate added to the end that easily enables the spindle to be
rotated through 90° for the second flat. The hole in the plate does not even have
to be central.
Outer Clamp Ring (24)
This part being 40mm diameter by just 4mm thick presents a problem to avoid ending
up with a small stub of material after it it has been parted off and that subsequently
may not find a use, never a good idea, but at larger diameters even more so. However,
the following method avoids that. Take your length of 45mm diameter bar (45mm enables
it to be turned to 40mm as concentricity is vital) and mount this in the three jaw
using the reverse jaws, unless you have a large chuck. DO NOT START UP THE LATHE
as it is likely that the end is well off centre and centrifugal force is likely
to throw the part from the chuck. With a short length of bar held on the top slide
advance this slowly as you turn the lathe by hand until the end is running reasonably
true and give the chuck a final tighten, STILL DO NOT START UP THE LATHE.
Now with a large centre drill in the drill chuck advance this using the tailstock
until it is very firmly against the bar when the lathe can be started on a slow speed
and the end centre drilled. This must be done such that the angled portion of the
drill enters by at least 7mm, the purpose being explained later. If you are using
a very long bar, say 200mm plus, then as a precaution the fixed steady could be added
but with a clearance of say 2mm between the bar and its arms.
Support the bar using the tailstock centre, face the end, and accurately turn to
40mm over a length of 8mm. Now, with the part still supported by the tailstock centre,
add the fixed steady setting its arms on the 40mm diameter just turned. Remove the
centre and bore the 16mm diameter, thereby ensuring that the inner and outer diameters
The bore should be no more than 4.5mm deep so as to ensure that there is still some
of the centre drilled impression existing. Once more, support the bar with the tailstock
centre having removed the steady and part off to 4.5mm long, Photograph 10.
It is essential that the part is a uniform thickness and to achieve this I located
some large washers that I added between the step of the reverse jaws and the workpiece
enabling sufficient to project so that it could be reduced to 4mm thick.
However. using soft jaws, suitably bored, would be a better option. Drilling the
part will be described later.