I mention this at this point as it is very relevant to the machining that is carried
out on the rear of the central boss. For me I just skimmed it until it was fully
machined as there is no dimension for the depth or the boss at the rear and then
continued with making the bore and the thread.
Ultimately, when the front face was fully surfaced, I was surprised just how far
this surface was from the end of the lathe's mandrel, especially as the notes said
machine to within 1/32" of the mandrel. To do this I needed to remove another 5/32"
from its face, no quick job even with powered cross feed available, and if not, then
a very tedious task. Therefore, if you wish to conform to the design dimensions then
you do need to machine more from the rear boss to avoid so much needing to be removed
from the plate's face. I did though eventually make use of this extra thickness as
I will explain but on the down side it does reduce the available space within the
gap by 5/32".
Machining the face
Having then completed the bore and thread the faceplate can now be removed from the
lathe's original faceplate and mounted directly to the lathe's mandrel when the face
can then be machined. As cast iron machines easily once the skin has been removed
I usually like to finish a surface using a HSS cutter. In this case though the slots
in the casting will still be in their cast state and the cutter may still find a
hard spot as it passes via each slot. If your lathe has power feed to the cross slide
this is definitely a candidate for using this, Photograph 3, if not, then you need
to be patient.
The faceplate is now complete except for a final dressing of the slots and a touch
of paint, but delay this until the angle plate is ready for similar treatment.
The angle plate
As I consider it to be easier to machine the angle plate on the milling machine I
have decided to adopt this method (saving time again), but for the benefit of the
lathe only workshop owner Hemingway describes a method of machining the angle plate
on the lathe and using the faceplate itself. Actually, there are similarities with
the two methods that I will touch on later.
As was done for the faceplate, produce a chamfer around the appropriate edges to
assist with machining. Check the base for high spots and dress as appropriate and
fasten to the milling machine table using hard card packing to protect the machine
table from damage and to limit distortion of the angle plate due to it not being
perfectly flat. With that done surface the top edge, Photograph 4.