Building the front pony truck
Whilst pondering the arrangement for the suspension I turned to building the front pony truck as another little self contained unit. First task to hand was to separate out all the components required, how many models have over 25 pieces for a simple pony truck? Again the attention to detail for the S7 kit is exemplary. The main castings, lateral control springs and base frame are all modified for Scale7.
I started with building up the springs and frames around the axleboxes, it all fits together neatly. However the axleboxes are cast for 3/16″ axles and the Scale7 bogie wheels use a 5/32″ axle. I resolved the mis-match by turning a small ptfe sleeve to reduce the diameter to 5/32″.
On the outside face of the bolster there is a lateral spring casting to be fitted. This shows the differences with going to Scale7. The short casting below the bolster is the spring width for the standard (“narrow”) gauge kit. So although Scale7 may only 1mm wider on track gauge when it comes to items like this the proportions of the casting (length to width ratio) are much more balanced.
The main bolster casting are then cleaned up and drilled for pinning, using a length of nickel silver wire. Soldering the two halves of the bolster together is entertaining, they have a fair amount of metal in them and work as a great heatsink. I went to my 75W iron for this job, alternatively use a small torch if you have one.
The axlebox assemblies are then fitted to the main frame followed by the bolster on top to hold it all together, an axle was pushed through the axleboxes to ensure that it was fairly square. Once I was happy that everything fitted it was soldered up.
The rear diagonal stays are then fitted and the side webbing on the main frame, finally guard irons are fitted, followed by a good clean up. The rear pivot attachment is left off at this point following a suggestion in the instructions to do so. Once the main chassis is complete and the ride height is determined then the attachment can be fitted at the correct angle.
As supplied the guard irons are presumably from the 7mm finescale version as once fitted on the Scale7 frame the irons were wider than the track, see the first photo. However they are fairly soft brass castings so a little tweak with the pliers and trimming with file got them to the right gauge, and also the right proportion.