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1:24 scale
H250 and H251
Driving wheels for the SAR 4-8-2 15F class.

5′ 0″ diam., 14 oval spokes, rectangular inner rim, 3½″ apparent tread.
Hubs 7.7 and 9.3″ face dias., 1½″ out from the tyres, pin between at 14″.

Source: works drawings 261, 263.

Casting: 63.5 mm tread dia., 55.8 mm i/d, hub 1.6 mm out from the tyre, pin at 14.8 mm.

Narrow gauge loco set prices . Casting prices and stock

Scan of the castings in a set for a SAR 15F

Scan of castings 250 and 251

Cross section diagram of castings 250 and 251
The hatched areas on the outer rim show where material can be removed for workholding before using a form tool.

The hub of the driven wheel, H250, extends at the pin end closer to the rim than does its very large weight. To avoid cutting into the weight I turn the middle of the hub in the normal way, but at the pin end I put the lathe into neutral and just rocked the chuck back and forth by hand while gradualy moving the tool further towards the edge.

Scan of machined castings 250 and 251

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27 Mar 2013