The eccentric strap was machined from some flat brass repurposed from a shower door hinge

The outside was mostly done with the rotary table before the vice to finish off the lug for the clevis.

I did not take any other construction photos as it is all much the same as other engines. Trial assembly ready for a quick test run..

Nigel, as far as I am aware the Scotchyoke is driven by the piston rod as it’s main aim is to eliminate the need for a crosshead and conrod thus giving a more compact engine. As I said it is the same bore & stroke as a Stuart 10 but comes out considerably shorter, ideal if you want to get it all below deck or just keep the ctr of mass low in a hull.

Alecs, next time I’ll order the sand blasted finish rather than the smoother bead blasted and then kick it around the workshop for half an hour.

Well as you can see from the above image it has now had a coat of paint and been mounted on a small base just to stop the flywheel touching.

Quite happy with how it runs. It is not the easiest engine to set up as the port face is on the cylinder which means you can’t set the valve to that as it is not solidly connected to the engine once the valve chest is open. I settled for checking that it had equal movement within the valve chest and did a rough 90 +30deg setting for th eeccentric. Just needed one adjustment to that to reduce the lead slightly and off it went.