Take a length of square steel, say 16mm sq by 40mm long, though the dimensions are
not critical, and turn the end over a length of 5mm to be a close fit in the bore
of the body at the non tapered end, drill and tap the end M5 by 10mm deep. This can
then be used to hold the Body, using a long piece of M5 studding, and to index it
to make the four slots, Photograph 4 should, I feel, make the method clear. The
packing below the square should be of a height that ensures the the saw just passes
into the 10mm bore, as too deep and the clamping washer will become too weak as the
slots are cut into this also. I used a large washer to clamp the body but would strongly
advise the use of a cup washer ( Sk. 1 ) as that would support the Body better, especially
when the last slit is being made and the part has become a little flexible.
The piece of steel seen on the right acts as a fence ensuring the part returns to
the same place for each slot. The photograph shows the task being undertaken on the
lathe for the lathe only workshop but a similar method could be used on the milling
machine if some form of dividing head is not available.
Securing Nut (3) and Head (4)
To avoid there being stubs of metal left after completing each one of the above make
them as a single operation as now detailed.
Cut a 42mm length (assuming 3mm parting off tool) of 30mm diameter steel, place this
in the three jaw and then for part 3, turn the 20mm diameter, make the 3/8” thread
and bore the 6mm hole. This needs to be bored rather than drilled to ensure concentricity.
Using the parting off blade reduce the diameter slightly to define the area to be
knurled, and produce the knurl.
Remove from the chuck, reverse and hold on the 20mm diameter just made and again
make a 20mm diameter this time for part 4, and repeat the above process to produce
the knurl. However, due to the force placed onto the workpiece when knurling, especially
if with a single wheel, and the part only being held on a 6mm length, centre the
end and support with the tailstock.
Next, bore 16mm diameter to a depth of 16mm, Photograph 5 and part off. Again though,
there is a potential problem regarding the security of the hold for this operation.
Providing your centre has a diameter larger than 16mm then this can be used in the
mouth of the bore for support whilst parting off, if not, then you must have foreseen
this problem and have made a headed plug with centre to go into the bore whilst parting
off is taking place. With the two parts now separated they can be held on their 20mm
diameters and the parted off faces faced to length.