Friday 2 May 2014

Thornycroft A1 Chassis - 3D print

Whilst waiting for Ed to find time to work on the baseboard (phase2)  I skipped from phase 1 to phase 3 of the project to see how well our 3D printer could make a Thornycroft A1 chassis in N gauge.

A1 Class

Introduced in 1924 the light weight A1 had a load capacity of 1.5 tons. It was sold as a chassis for customers to add their own body work or supplied with bodywork from Thornycroft's range of styles. A war department subsidy of £120 was available to customers who opted for it, which meant in times of need the War Department could requisition the chassis with or without bodywork at a reduced price from owners. The book price of a chassis in 1926 was £460.

The Model

It was very common to see vehicle chassis in the yard at Thornycroft so it is the chassis that I initially wanted to make. A dimensional drawing is available from Hantsweb and the kit of parts I drew up in FreeCad.

The kit comprises:

  • Wheels
  • Front Axle
  • Rear Axle
  • Engine compartment
  • Chassis with built-in cosmetic leaf springs
  • Drive shaft with gear box
  • Steering wheel
  • Steering column
  • Gear lever
  • Petrol tank
  • Exhaust pipe
Quite detailed for N gauge.

The paint finish of the assembled chassis is a big unknown because only monochrome photographs have been found and most of these suggest a lighter than black colour. I have not found any written records of the stock finish. I assumed they would have been stocked in primer paint to be finished in the customers livery before dispatch. I chose a red oxide colour (Humbrol 100) but grey may have been used in reality.

The chassis will be positioned outside the paint shop on the layout.


All the parts are so small that if they are 3D printed individually the plastic filament does not have enough time to get flowing before the print finishes! So I ended up making a batch of 5 for greater coverage! 


They turned out better than expected and I'm looking forward to making a bodied version and some other vehicle types. I quite fancy one of the six wheeled lorries.

David

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