Relay Resurrection

The restored relay clock, in its original glass case

I have renovated the components of my nearly 50-year-old digital clock. The next step was to assemble it all back together. Would it actually work?

The old broken and abused internal plexiglass chassis was replaced by new plexiglass, providing an opportunity for me to learn the technique of plastic welding, where a syringe injects solvent into the edge of a surface-to-surface joint and spreads by capillary action to the full contact area, partially dissolving the plexiglass, which then forms new polymer bonds between the pieces. It takes a few minutes for it to start hardening, which gives some time to prop the parts in the desired position (use a square to get the angles right). It is completely cured in 24 hours and is truly “welded”. Like a good metal weld, a good plastic weld will break elsewhere if enough force is applied.

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