Simplex in 7/8ths: 3D design

Alongside the smaller items on my workbench I've also been working on the 7/8ths Simplex. Looking at prototype photos and studying drawings showed that I'd either have to fabricate lots of similar items, or come up with some way of replicating them...

So why not combine my skills and work with what I know. With that in mind I fired up Sketchup and starting drawing up some of the more complicated or repeated items that form the basic details for the 40S. Front to back left to right you have four sandboxes and lids, these are a more modern design then the 20/28 version, and the lids have a lip so they locate positively on the top of each sandbox and could be posed open, bent or slightly ajar. The next row are four axleboxes with bolt head detail. The leaf springing is slighly represented at the top and this also forms the surface I will use to glue these in position behind the plasticard side frames. In front of these are four brake shoes, slightly reduced in size from the prototype as I will be using 30mm diameter (rather than 34mm diameter) wheels. Front row, you have a filler cap, not sure what for but it's shown in different positions on the 40S photos I'm working from, sometimes in the lid of the hatch, sometimes protruding through the back under the controls. On the right is some sort of filter canister (in two parts) which is hollow and goes next to the radiator on the front.

I have sourced a few parts from Si at Model Earth including coupling blocks, radiator and a seat - intended for a 20/28 these will need a little modification for the later model 40s but are beautifully crisp mouldings. I hope my details will due them justice.

To power things I've commissioned Peter at PDF models to come up with a suitable drive unit that has chain drive to both axles from a centre motor, like the prototype, and that as much is visible as possible.

More soon when the parts gathered together start to form a model...