Chassis for the Furness Railway J1 locomotive, designed as a fixed axle.
The axle holes need gentle reaming out to accept 2mm 'straw hat' and 1/8th 'top hat' bushes (bearings) Reaming them out slightly downwards to an oval and keeping the bushes loose makes a little bit of downward play to help with track holding and electrical conductivity. In trial builds the driving wheels were sprung downwards like this with the pickups killing two birds with one stone so to speak.
A spacing plate is sprued to the left hand side, this is to be cut off and glued in position relative to your motor and gearbox choice. It makes a good motor mounting plate too.
For the rear wheel you have the choice of a Pony type pivot arrangement or a double joined option more like the radial truck, use 10BA nuts and bolts, to fix these in place using the hole in the rear of the chassis (ream to a working clearance), add straw hats to these working pivot parts for best results, reaming them carefully to accept them tightly. The front chassis hole that is designed for body fixing is only to be reamed out only a little bit as the bolt will self tap, a retaining nut is not needed unless you want to add one. Brake pads are already in position but you will have to make your own brake rigging if required, on the insides are dimples to accept some thin brass rodding. 0.45 is a good choice.
Owing to various conflicting written information and drawings regarding the driving wheel diameters the descision was finally made and the chassis are designed to use Alan Gigson 5' 6" driving wheels, code G4866 for 00 and EM and code GS866 for P4. These wheels also have the correct crankpin throw. The front and rear wheels are 3' 6", Alan Gibson codes G4842 & GS842 respectively. No doubt other companies wheels can be used also, but they haven't been used in the initial builds to be able to advise accurately.
The slightly larger quoted (elsewhere) wheel sizes no doubt could be used with a bit of tweaking also but I'd go with the above as they are guaranteed to fit.
A London Road Models 1/50 Motor Mount (Gearbox) and a Mashima 1020 motor with added 6x12mm diametre flywheel with 1.5mm shaft hole was used in the photographs of the completed locomotive. (Please see the loco bodies section) Again, many options are available but these are known to fit easily. The only potential problem with this combination is a small hole in the cab below the firebox hole had to be cut out for the gear wheel, but after backhead, levers and crew were added to the finished locomotive you could only tell if you looked hard enough.
Here is a video of the J1 running. P4 in this case.
If you have any questions feel free to ask and I'll try to get back to you asap.