David Franks
Hi Phil, sorry no-one has answered your query yet but if I can help with my experiences, the chassis width can vary a bit depending on the loco wheelbase and the radius of your curves. most people including me usually go for 14.5mm over the chassis frames, I make my frames from 0.5mm brass so the stretchers (spacers) would be 13.5mm. Nice and easy to work with and strong enough for big locos if you fit the frame stretchers in the correct places, I have a few locos with 15mm over the frames but found it doesn’t leave much room for plunger pickups that I like to use but they do go round my minimum 4ft radius pointwork in the fiddleyard. I have one loco, a J39 which is a long wheelbase and that very occasionally causes bother by shorting as the centre wheels are so close to the frames which are a smidge over 15mm so that one is only used on the outer circuit of the layout, a scratchbuilt chassis for an 8F which is 15mm overall works perfectly and both are sprung.
Hope that helps.
Dave.
Just noticed that the info says ‘member since April 2011’ that should read ‘1985’…..