Photograph 21 shows a typical task for the machine in which the bearing cap, having
already been completed is being used to position the holes in the lower portion of
the main bearings. This was followed by drilling the hole (prior to reaming) for
the flywheel spindle, Photograph 22, and was the task where the problem surfaced.
When using a standard drill there is a tendency for this is to be drawn in to the
gun metal casting, because of this the chuck was pulled from the taper on the machine
spindle. Fortunately, I had, as one should for a task such as this, clamped the vice
to the machine table as can be seen in the photograph.
I should have removed the helix from the drill's cutting edge as is the norm for
drilling brass and similar materials but as I normally work with mild steel was reluctant
to modify my drill as I would then have to remove a fair amount of the drill to get
back to a cutting edge suitable for my normal uses. With a lot of care and quit a
few failures I eventually managed to complete the two holes, one should really use
the appropriate drill. Even so, I had no problem drilling the large number of smaller
holes in this material using standard drills.
Finally, in terms of machining activity, I will comment on the cylinder assembly
showing a few operations involved with this including two that show that the milling
head set-up is more than a match for even quite complex tasks.
Whilst the cylinder block is quite large and certainly the most complex item that
the engine requires, most of the activity is of a simple nature, as a result, they
are tasks that I will not expand on.
Having accurately bored the cylinder block to the required diameter using the 1"
diameter of the locator jig to act as a gauge, the jig was again used to position
the drilling jig for drilling the six holes on a PCD as seen in Photograph 23. Using
the tapped hole on the rear end of the jig, a bar was clamped onto the other side
of the cylinder that was then held in a vice as the photograph shows. The process
was repeated for drilling the holes on the second end
As the cylinder end flanges have a 1" spigot for locating them onto the end of the
cylinder this could also be located in the drilling jig allowing the jig again to
be used for placing the holes on a PCD, Photograph 24. The four sets of six holes
were therefore made with ease, but far more important, with a degree of precision
that would not be possible by any other method