LETCHWORTH ENIGMAS – Mechanical

The Letchworth Enigmas are built up from the plates mentioned in an earlier section

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This is a close-up view of one Letchworth Enigma showing the detailed machining that has taken place. The pair of bars towards the front are the carry bar roller pins. The rollers rotate on these as the carry bars move across the machine.

This assembly is now ready to take the three main drum shaft bushes pictured below.

These bushes at this stage have still to be hardened, the inside diameter honed to size and the outside ground to dimension

Above are the long top (fast) drum spindles. Also can be seen is the jig made specifically to accurately align the drill holes for the cross pins which drive the drums.

Above are the same shafts with the support rings added. When replaceable commutators are fitted the drums have to be positioned further out from the front of the machine. Rather than design new longer main bushes, these rings were fitted instead.

At the rear of the top drum spindles these ‘diamonds’ are fitted. Those shown above are complete and ready to take ratchet pawls on the small posts and for the worm wheels later screwed to the rear.

Following this, the remaining main spindles are to be fitted from the front of the plates and the drive mechanisms mounted and pinned to the rear. In this view, the spindles are the shorter versions used for the seventy-four medium and slow drums.

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