COMMUTATOR
When all 104 studs are screwed onto the special mounting plate the outer two rows have to be aligned. These have flats that need to be correctly positioned. With the screws lightly tightened the studs in the outer two rings are roughly aligned and then the assembly is pressed into the jig, which completes the alignment.
The two inner rings of studs are round in section so they do not need aligning.
Here the studs are correctly positions and all 104 screws can be tightened.
The ring is then removed and the whole assembly placed studs down into a shallow temporary dish. This is then placed in a vacuum chamber where the 'plastic' material is poured around the studs and up to a predetermined depth. Vacuum is then applied and the material is allowed to set.
The whole assembly is then taken from the vacuum chamber, the temporary dish removed and mounted in a lathe chuck. Here the face is turned until flat and the outside cut to the correct diameter.
The final action is to remove all 104 screws. This is yet another labour intensive activity which Ian Walker has kindly carried out with the help of others.
Letchworth Enigmas - Electrical