Reference to photograph. 2 shows that the moving internal dimension jaw moves along
on top of the main mounting member, there being just a very small clearance between
the two. This arrangement helps to avoid damage to the caliper if too much pressure
is placed on the control buttons as it will support it if that happens. I was though
pleasantly surprised just how robust the mounting was.
It is though absolutely essential that the caliper is perfectly horizontal else strain
will be placed on the unit as the saddle moves left and right. To ensure that this
is possible there are two screw positions (X and Y) shown in the mounting arm though
only one is required, which one being determined on initial assembly. The purpose
is to jack up either the left of right hand edge of the arm as is found necessary
to set the caliper horizontal.
It is also vital that the caliper is parallel with the lathe's axis else similarly
strain will result on the caliper if this is not so. This will be set by moving the
caliper's head slightly under the clamp.
Both these requirements can be tested by setting the caliper's depth bar in the fully
out position and with that done use the saddle to push the bar back in. If there
is an error the end of the bar will be seen to move on the side of the cross slide.
Typically, if there is an error such that the caliper is closer to the lathe's axis
at the outer end then the end of the depth bar will move away from the axis as it
is being pushed into the calipers main arm. It will of course be necessary to carry
out these tests each time you add the milling head to the lathe.
Series Seven owners will have noticed that it was necessary to remove the top slide
clamping screw as it would foul the bar clamp assembly. This though is of no consequence
as the top slide would be removed when the milling head is in use, though closing
the large hole with a plug is a good idea and is one item I still have to make. However,
if the top part of the clamp is removed the screw can fitted allowing the lower portion
to remain in place when the lathe is being used for turning.
Having completed the fitting of the digital caliper it has become obvious that it
would have significantly helped in machining the horizontal mill engine
and will be a worthwhile addition for future projects.