1" Minnie Traction Engine
By Stephen Meredith
- Working Progress (Gears)
Following the completion of a small marine steam engine "Trojan Engine", I decided to tackle a larger project. Having visited various shows and the model engineers Exhibition, I decided to buy the Construction book for building the popular 1" scale 'Minnie' traction engine.
The initial workshop experience was limited but keen to learn, and research has enabled me to get it this far.
As can be seen, this is basically finished well almost, it steams, and runs well a few tweaks are needed but tweaks don’t make piles of swarf.
The intention was to show the engine and run it, at rallies but what I really wanted was a capable engine that could pull an adult or (me) on a field. This engine was, therefore, a stepping stone to be able to tackle the engine I wanted. After research, I bought a set of drawings for the Plastow 3” Burrell engine and started gathering material and tools needed.
The 3” Burrell.
This is what I hope to end up with, a large usable engine capable of pulling the driver and perhaps a passenger on the riding truck behind.
The first part I started to tackle was the smokebox tube, and this just fitted nicely on the lathe as it is being a 5" lathe. The only part that I am sure will have to be made on another machine is the final drive gears and the flywheel.
Not my work! but an example of what I'm heading towards making first.
Smokebox name - I couldn't resist buying this to make the front end look complete and as it was our bronze wedding anniversary recently so my wife bought it for me.
The casting of the letters needs close attention, with a file, to address each letter to end up with a good result.
I try to remember it is a casting, and as such, the idea is this reduces the amount of machining required so to preserve the casting feel. I'm trying not to fully machine each part, as this ends up with a result like my Minnie cylinder block, fully machined on every surface.
Interestingly some of the gears in intend on making require the fabrication of a new index plate for the dividing head. 17 Tooth drive gear and 27 @ 10DP - 20Deg PA
Assuming I need to clamp the smokebox to the rotary table i made a plate to aid clamping.
Made the small name ring plate for the smokebox however when the casting arrived for the door it appears this detail was already cast in the part so this ended up as just a turning exercise for now.
Following a visit to the Midlands model engineering show I managed to buy 3 of the gear cutters required to make a start on gear cutting, I need to finish the dividing plate above but then I should be able to attempt a test gear in aluminium first before trying this new skill out on a Mild steel blank.
Finally found a fixed steady at a good price from the same show as the gear cutters, this is working progress as it needed raising by about 10mm to be on centre line. However, the price paid justrifies the additional work required, and with a fresh coat of paint applied (shown here) is looking the part already.
It looks like an expensive stew pot, but this is the beginning of the front end. The aluminum ring is just simple turning to fit and the door is still to be turned here is just placed for a mock-up photo.
The letters on the name need treating to some careful filling treating each letter in isolation to get the required effect simply turning it would end up with some of the definition being lost.
The center boss needs turning to incorporate the smaller name ring not shown here, but it is somewhere in the workshop.
Small progress made, but all holes drilled on the rotary table and ready for drilling the aluminum front ring and then 18 x M4 dome head Allen key bolts. The use of the rotary table gave a nice accurate result just requires the lip machining a bit deeper as the holes on the front ring are close to the edge.
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