Looks like I need to find myself some suitable brass angle, taps, etc
We used 10BA CSK bolts from underneath the lugs on the resin bogie sideframes. The "angle" was something like 8mm x 8mm U-section with a wall of circa 1mm (that is the crucial part of what we did, need the thickness to give sufficient "threads"). I recollect that the section came from Metalsmiths (before the split / sale of the company). Peter cut one side of the "U" off to give the required angle.
You ought to be able to get what you need from traders at the Reading Trade Show on this coming Saturday.
If you intend to do something like our approach then please check before you start:-
1/ all of our resin sideframes needed to be "straightened" along the frame, both in/out and up/down directions.
2/ the contact face between the angle and the resin bogie sideframe is the top of the lug of the resin sideframe... that surface needs to be at right angles to the rest of the moulding otherwise the bogie sideframe can be tilted with respect to the ABC bogie.
3/ the resin sideframes, when fitted to the brass bogie frame using the pegs on the lugs, were not centred correctly... Peter removed the pegs, aligned the sideframes relative to wheel centres, and then spotted through the resin lug into the brass angles (which had been soldered to the ABC bogie).
Yes, there is a fair bit of Mk1 eyeball engineering here, just take one step at a time and think through how to get from A-2-Z in 3D space. What may help you is to build up a JLTRT resin inner / outer frame with wheels in the outer locations... put the bogie on a flat surface.... and then measure from the surface to the top of the resin sideframe. You now have a reference dimension for adjusting the location of the brass angles / remedial work on the resin lugs (and mark the reference point on the top of the resin sideframe so that you get make your measurements in the same place each time).
regards, Graham