Time for another little one to join the collection, this time it is based on the Stuart One-One or No 11. Up until about 5 weeks ago I had not even heard of this engine from Stuarts but an image was posted on the Stuart Models Face Book Page of what seems to be the only one in existence on the net. A following reply included a scan from an old catalogue and that was enough to get me going. It was drawn up over the next couple of evenings in Alibre and the Little Otto put on the back burner while I made this one.

I made a few changes from what I could make out of the original.

– As I wanted to make it all in metric rather than go down to 11mm bore which would have been the closest whole number to the original 7/16" bore I went up to 12mm as more will have a 12mm reamer than an 11mm one if anybody wants to ream the bore.
– The bed "casting" has less draft at the ends as I had a piece of aluminium in mind for it when doing the design, in the end I opted for some cast iron but stuck with the same 2degrees of draft all round.
– The original looks to be a single acting piston valve design but I went with double acting just to make it a bit harder to make
– I think the original used the "progress" flywheel but after looking at Stuart's the likely cost with VAT and postage was going to be about £22 so I cut £3 worth off the end of a piece of 65mm dia cast iron bar and cut my own on the CNC but still sized it so a progress flywheel could be used.

It's a quiet runner when not on the table in the video which amplifies any sounds and will run nice and slow as well has having a good turn of speed when the regulator is opened to let more of the 5psi of air through. just shows what can be done with just digital callipers and no micrometer

Edited By JasonB on 14/09/2022 19:53:57