Friday, January 21, 2011

Getting cranky

Crank pileWith the con rods rotating well, the next step was to build and fit the cranks that on the real locomotive would drive the thing. Three sets are provided on the etch. A nifty shouldered axle is also supplied.

Sadly, none of the centres are big enough for the axles. Attempt 1 saw me clamp each lamination (3 per crank) in a hand vice and ream out the centre. Result, squashed brass lobes.

Attempt 2, the crank was soldered up and then reamed in the same way. Still not very effective and the lobe still squashes.

Number 3 - ream the axle hole while the part is still on the etch. By this time I'd found that a tapered reamer was more gentle than a broach and all the holes were made the right size. The crank was soldered up and another problem reared it's head.

You see, this is a HO model and the kit has been produced by reducing the etch photographically. That's fine except I have several cranks whose throw doesn't match the wheels. By at least 1mm. The only way I can make this work is to bin the lot and make new cranks from scratch. And I can't be sure of the throw on the wheels. Even if I could, I bet I'd screw up the measurements.

So, plan B is to build the diesel-electric version.

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