Stuart One-One (No11) Replica

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

Nice looking job Jason.

Cracker as always. I like your currently fashionable retro car colours - this one definitely looks like eau-de-nil.

Rod

Once again Jason, a deceptively fairly basic engine impeccably executed. A good looking result and a lovely runner.

Jim

Thanks for the comments, colour is Ford "Forrest Green" it's a bit light in the photos but where I'm holding the engine in my hand in the video is a better colour match.

Nice build, Jason.

An excellent resurrection!

probably Stuart would be interested in your work and the drawings, if they no longer have them.

You may have started something!

Howard

Thanks

The wonders of Facebook have furnished me with some more information about the One-One and it turns out that is was double acting after all. From the Youtube video of an original could only see the steam exhausting from the far end of the piston valve housing so assumed single acting but as the sketch below shows the exhaust from the other side of the piston passed through the hollow valve and out where I could see it.

Oh well I'll just have to find another project to use that setup, Stuart Meteor replica maybe as that seems to have used the same extruded brass "teardrop" section for the cylinder.

This is how the original was done

Whereas mine has two 2mm holes out the bottom of the valve chamber as exhausts, one end being closed with a plug, the other with a screw in guide/gland