Great big whirly cranks are a nightmare on model locomotives. Most kit-makers suggest something that flaps around on the chassis with loads of slop in the coupling rod/crank pin interface. This works but doesn’t look nice. It’s a good way to get yourself some jerky running too.
The cranks are much better. A development of Mercian’s Barclay cranks, they are made of laminations which fit on the end of a Romford axle. This sorts out the quartering and keeps things tidy.
I didn’t use all the laminations this time – P4 modeller may need a bit more chunkiness but these have to tuck behind OO spaced rods.
I screwed the first two bits of metal to the axle as they have the square centre holes and then held the others (with round holes) to them with sprung tweezers. Solder is run around the edge and then cleaned up.
Result – a nice chunky crank. A little bit of filler would hide the laminations but under the footplate, behind the steps, no-one will notice.
To finish the job, I tapped the crank pin hole to 10BA so a Romford pin will screw in. It could just be soldered in place but I thought I'd go all engineering.
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