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My home-made radiotelegraph key. The base is heavy, made from a piece of 1/2" x 2" steel covered by a brass sheet ornamented with "spotting", a technique I learned as a clockmaker. It has ball-bearing pivots. The lever part is steel, colored with gun blue.
The knob is made from an old screwdriver handle, and the rubber feet are really ball-cock gaskets from the plumbing store. The supports are sawn from brass with a little jewelers' saw, which is one of the world's most useful tools. The insulating washers for the contacts and binding posts are turned from PVC.

Like all keys, the gap between the contacts is adjustable, as is the spring tension. The pivot adjusting screws are just 6-32 by 1/2" set screws from the hardware store, with an appropriate hex nut. The rest of the brass adjustment screws and and the binding posts are home-made, using a small lathe.
A drawing of the pivot bearings. The ball is from a broken ball bearing. It is very hard and smooth. The 6-32 hex-head set screw has a cup on the end which fits nicely against the ball for a low-friction bearing. There is a simple hole in the end of the armature arbor which also has a cup, due the point on the drill.