Someone asked off grid to explain how the revised bogie pivot and side control worked, it's quite wordy so skip to the pictures if you wish.
The kit is designed with the bogie pivot behind the bogie and under the leading brake shaft, it works fine for r6' + curves but anything tighter and we need to reconsider options. The only downside to the pivot being this far back is that the bogie has an arched lateral path and thus runs the risk of shorting against the leading brake shaft support, it also restricts any rotation movement of the bogie as well, but it's simple and it works.
I personally prefer a pure linear lateral movement and so you need the pivot in the centre of the bogie and by good fortune/forward planning the bogie stretcher has a perfect oblong slot we can use, much bigger than normal but we can work with that, very well as it happens.
Having lost the rear pivot point between the frames you now need to add the chassis bogie stay, note it's cranked downward to clear the inside slide bars and cross heads....like the real engine. Attached to the underside I fitted a brass tube pivot point which is a snug fit in the slot and above a 6BA securing nut. The bogie is a lovely light weight etched affair, so our side control needs to be minimalist and I just added two long prongs of spring wire to the rear of the bogie. This is our side control but I also added two prongs in front and these are our rotational control stops.
In the centre of the brass tube is the down force spring, a washer is placed on top and then the bogie fitted, finally a screw with corresponding large washer is fitted and the job is complete.
The end result is a linear lateral movement with side control and a rotational aspect permitted as well. The two prongs up front have a straightening moment on the bogie, which keeps the rear bogie wheel from getting too close to the leading brake shaft support, it also limits the far side from hitting the inside of the outside cylinder block.
Currently the rotational stops are a bit tight and the inside leading wheel is just lifting; I need to open the prongs out a mm or so and add a bit more down force.
It's a lot of work but it's near invisible and does reduce the amount of front overhang so there's a big plus for visuals as well. It'll also allow me to now add the inside cylinder block which sits down inside the leading bogie wheel.
