Harold Hall


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 the part.


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 surface.


Workshop Projects

Tilting angle plate, Adjustable angle plate, Pivot
Soft Jaws for the three jaw chuck, using




Tilting angle plate, Adjustable angle plate, Machining