Glad to hear that it worked first time. Burner design is very much a 'suck it and see' exercise, as there is no published design data around for garden scale butane burners. What little info that exists is empirical and about building burners for internally fired boilers.jefran wrote: ↑Sun Jul 31, 2022 4:21 pmit is so quiet that the ambient noise outside made it hard to tell whether it was burning, and in the first few minutes it went out a few times, but it then ran nicely for about 20 minutes, with the loco running on blocks. I had to put some more water in a couple of times but the initial tests seem promising.
There are two main reasons I use the Roundhouse type of burner. One - they run quietly, especially when turned down after working pressure is reached, so much so that I have trouble hearing them outside. Two - they are more efficient than the older slotted design.
If you don't have machine tools and skills to make burners, you can use mesh to quieten down the slotted type, but it also restricts the gas flow, which reduces heat output.
To be honest, I'd seriously consider ditching the liquid butane feed arrangement for the much simpler gas feed normally used in commercial models. Some of your lighting and running issues may be due to variation in the liquid feed rate.
Drilling all the holes in poker burners is a problem as you found. My bench drill has enough slop in the quill that it is useless for precision work. I use my small mill for most of my drilling work, as it allows for co-ordinate drilling. Next best choice of machine, in the absence of a mill, would be to use a vertical slide in a lathe.
I now use a spotting drill to put each row of hole centres in the metal, as it's hard to centre punch a long straight row of hole centres by hand. Before a friend put me on to using a spotting drill, I used to use a centre drill (slocombe drill) to mark the centres.
Drilling holes in a tube isn't easy, but by holding the tube in a milling vice, carefully setting up and using spotting drills, I've drilled the holes in seven scratchbuilt burners so far and I'm still using the same 1.4 mm drill.