Some years back I built a vertical boiler oscillating steam engine it was my own design but was essentially a Jenny Wren look alike. Ultimately it was a failure, it ran nicely on 4-5psi of compressed air but would not steam using a single wick spirit burner, as it was meant as a xmas present for my father in law I ended up putting it aside and making a horizontal boiler version which could use a double wick burner, this solved the problem and the present was a success. It always bothered me that I was unable to get the vertical boiler version to run with a spirit burner, so recently I've started from scratch again with another vertical boiler version of my own Jenny Wren look alike design and this time I did have success, I now know that my first engine issues were more than likely due to sloppy workmanship - fit and finish of the piston and cylinder and minor misalignment of the moving components which caused friction at certain points of the crank rotation which could be felt as a roughness when the flywheel was slowly rotated by hand. While my current engine runs with a spirit burner I found spirit burners can be finicky and seem to be sensitive to the wick height and also the amount of water in the boiler, I decided to augment the spirit burner and make a additional burner fueled by butane, I wanted it to be of similar size and appearance to the spirit burner which meant it would be an all in one construction. The photos show the completed burner, the butane resevoir is the same material that I used for the boiler the gas jet is one that I had on hand I'm not sure where I picked it up, the hole is small I did have some trouble determining the size but as near as I can figure it is .003 -.004 in, this is around .09mm, I also tried a .006in jet (approx 0.15mm) but that gives a yellow flame so clearly it is too big. The fill valve is my own construction using components salvaged from a refill-able gas match, the refill valve body for this was made of plastic so I removed the seals, spring and tube and machined up a new valve body from brass with a 5mm external thread, alternatively they are available on the 'bay being sold as air soft bb gun fill valves and are quite cheap. The control knob shuts off and regulates the gas flow for flame size. It works well - with 5-6ml cold water steam comes on in just under 1 min, it is surprising how little gas it uses a 2 second 'squirt' from the butane gas refill canister is enough for almost 10 mins of burning and being able to control the flame means the speed of the engine can be varied.