Modified hinge assembly
I have mentioned above that I modified the hinge assembly from a purpose made screw
having a parallel portion to a bush with a standard screw passing through it, this
is shown in Sk. 2. The sketch should be reasonably self explanatory but the viewer
may be interested in my method of producing the parts using a fixed steady. To avoid
a short stub being left in the chuck having made the parts, I made them whilst a
much longer length was supported by a fixed steady. See my pages on using using steadies.
One of the spacer washers needs to be machined to give a close push fit between the
two adjacent lugs, this best being done whilst supported by suitably machined soft
jaws, Photograph 14. With there being a substantial gap between adjacent jaws the
thickness can be easily measured with a micrometer without the need for removing
Above, I said ”one” as the first one can be made to a nominal dimension and then
fitted and secured with the screw and nut passing through the lugs. With that done
the distance between the other two lugs can be measured and the washer machined to
something very slightly larger, then lapped on a sheet of emery paper until if goes
in with a stiff push. I am fortunate to have a set of slip gauges to determine the
size of the gap but a pack of feeler gauges and a micrometer will do almost as well.
Photograph 15 shows a close up of the assembly.
The parts should be assembled using the parts just made and again secured to two
angle plates mounted onto the milling machine table, rather like that seen in photograph
11 but mounted nominally at 45° to the machine table. The reason for placing them
at an angle was that if mounted as in the earlier photograph the base of the rear
angle plate would hit the machine column before the cutter could reach the front
edge of the angle plate. As a large machine would be needed to avoid this I assume
most will have to adopt this arrangement.
As the lower edges of the angle plate are unlikely to be in line at this stage do
ensure that the castings are fully against the angle plates rather than in contact
with the machine table. Machine the edges as shown in Photograph 16, repeat for the
other end but this time ensure the edges just machined are in contact with the table's