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Elmer’s ‘Tiny’ #23

Jim Greethead from New South Wales enjoying a pint of amber nectar at the recent Bristol Model Engineering Exhibition during a recent visit to the UK.

Jim Greethead from New South Wales enjoying a pint of amber nectar at the Bristol Model Eng Exhibition during a recent visit to the UK.

Jim's trio of beautifully built 'Tinys' each fed with air from a neat three way manifold.

Jim's trio of beautifully built 'Tinys' each fed with air from a neat three way manifold. I think Elmer Verburg would have been well pleased.

As soon as I heard that ‘Aussie Jim’ was building Elmer Verburg’s #23 ‘Tiny’ I asked Jim if he would consider taking some step by step photographs and prepare write up notes on his build procedure. The following is the result.

Jim was recently over here from his home in Bywong, NSW, Australia and made a point of visiting the 2009 Model Engineering Exhibition in Bristol.

Thanks Jim, this is a first class article and introduces a number of innovative solutions to problem solving from which we can all learn - so over to you Jim for the full story……….

Building Elmer’s ‘Tiny’ Engine

When I saw the Elmer’s Tiny that John Somers built, I knew that I just had to have one. This story is not a tutorial or an instructional article, it is just a few photos and a couple of things I learnt on the way.

The first task was to convert Elmer’s drawings to metric to suit my workshop. This involved DesignCAD and quite a bit of learning. It would have been faster on the back of an envelope but I need to learn DesignCAD anyway. You can see a couple of pencil changes to the drawing as it appears in the photos but it was good enough to work with.

The next decision was whether to make it in aluminium (my favourite material - easy to work and it is clean), or brass (looks good but is expensive and the finished engine needs polishing ) or stainless (hard to work and the only available piece of unknown origin). It seemed easier to make three then to decide between them and, as everyone knows, it is just as quick because the setup time is shared. Mind you, I think “everyone” knows this from theory not from experience.

click for part two >>>

Elmer’s ‘Tiny’ #23 part two

The crankshaft bearing was completed before moving on to the cylinders.

The crankshaft bearing was completed before moving on to the cylinders.

Having completed the three engine bodies Jim’s build moves on to making the crankshaft bearing before tackling the cylinders

Machining the body was a bit traumatic; three broken drills and three restarts from scratch so for a bit of light relief I made the crankshaft bearing next.

Almost nothing can go wrong with this job, and nothing did. The bearing hole doesn’t need to be reamed, I just drilled it , 2.5mm and then 3mm. I then turned the outside to size, checked that it fitted in the hole in the body and parted it off. After it had been reversed in the chuck and cleaned up, the job was done.

And now the cylinders

The pistons and crank disc came next

Incidentally I noticed that in one of his other designs Elmer uses a press fit for the pin. Despite the difficulties of getting the tolerances right at this size, I might try that next time. This time, I cheated and increased the size of the hole in the piston.

click for part three >>>

Elmer’s ‘Tiny’ - part three

The flywheels

Three flywheels to make: brass, aluminium and stainless. It’s a simple task so I didn’t take too many photos.

And lastly, a note on the springs

You can forget all the fancy stuff, I ended up manually rotating the chuck and advancing the slide. The springs were actually quite tricky.
I made the first ones to minimise the pressure (and thus friction) between cylinder and body. But I found that the cylinder lifted off at angle, jamming the pivot pin. They were alright at 5psi but not at 20psi. So I had to experiment to get a spring that worked at 20 psi and still allowed the engine to run at 5 psi. Anyone got a use for a small box of springs?