In an endeavour to stay with tungsten cutters I decided, as an experiment, to try
using my boring head for the purpose and even though the cut was intermittent the
arrangement worked quite well providing the depth of cut was kept to a reasonable
value, 0.3mm I seem to remember.
I marked the two machined faces with marking blue and scribed machine-to lines to
define the width of the vee, being a distance of 60mm, and was positioned to be an
equal distance from each end of the casting, nominally 30mm. I mounted the casting
on the angle plate setting the faces to 45°, doing this away from the milling machine
on the surface plate as the larger surface makes it easier to use the protractor
from my combination square. Having done that it was transferred to the milling machine
table and the vee made using the boring head as mentioned , Photograph 5. When machining
these faces one can stop just short of contacting the other as a groove is made
in the bottom that will remove any unmachined surface.
The casting was next tilted the other way and the second surface machined, in this
case the machining forces were away from the angle plate which is not ideal but this
was difficult to avoid and with the light cut being taken there was no problem. With
the angle plate still on the machine table the casting was moved to the horizontal
position and the groove in the bottom of the vee made.
Having finished the vee I was now able to machine the two fixing slots ensuring that
they were equally spaced about it. To do this I clamped a piece of round material
in the vee which gave me a reference point for setting the position of the slots.
Again using the square posts, Photograph 6 shows the set up with the first slot
I chose to make the slot centres, rather than as per the drawing, to suit my Hemingway
Quick Set faceplate, machining this being covered elsewhere on the site.
This now leaves the ends of the web that needs a rather special setup to ensure that
the vee is central to a fair degree of accuracy. The casting was positioned on a
round post fixed to an angle plate and set vertically as shown in Photograph 7 and
then machined. Next I rotated the casting through 180° setting it vertically once
more and machined the second end using the same downfeed setting as for the first,
Photograph 8. These operations could not though be carried out at this stage as
they needed the clamp and its fixings to be completed.