Back at Christmas I had a chat with Bill Blackburn on the topic of replacement wheels for new Farish mechanisms. I have a class 04 chassis waiting for conversion to 2mm. I made up some 7mm dia wheels from Association castings, but rather than turn a stub axle, I bored the centre to ~2mm diameter to fit the Farish insulated bushes. A carefully measured boss was left on the rear of the wheel. The wheels where then pushed onto the Farish axles (with their plastic insulating bush) to achieve correct back-to-back with the Farish stepped axle.
This week I finally got round to sorting out some crankpins and reassembling, as the photo shows. I had to make up my own crankpins (14BA) and spacing washers as I haven't got a tap in my collection which matches the Farish crankpin (I think it might be M1, which is a standard size, but my metric sets run out at M1.6).
The rods are still full Farish thickness, the wheels need balance weights, and, for a Class 04 the spoke profile is wrong (though the spoke profile is suitable for an 03 and most of the other small BR shunters). Having taken the picture, I can now see that I've forgotten to file the head off one of the crankpin screws (job for tomorrow).
So, its the proof of concept. Its an open question as to whether its worth pushing into production as an alternative to re-profiling Farish wheels for their more recent locomotive designs.