Scott

Tubal Cain wrote up two small boilers in ME, a 3″ one and a 5″ one. The build article for the 3″ one ran from 18 Feb.’77 to 1 Apr ’77, and the 5″ coal fired one from 18 Aug ’78 running to 6 Oct ’78. Here’s my example of the 3″ one, runs the #10 no problem.

John

Re. Tubal Cain’s boiler designs, he actually wrote up two 3″ designs in 1977 ME, the first one in the two January editions. This is a very simple design which he claimed was “knocked up in an evening” to run his then recently serialised Williamson engine and his version is spirit fired which is perhaps the best arrangement since water level is gauged by test-cocks. I notice that a design drawing is available commercially, but without construction notes.

Back in the day, I made TC’s other 3″ design, as shown earlier in this thread, which runs my small Stuart Turner engines more than adequately. It’s fired by a gas burner but water level needs to be watched as the water volume is fairly small. It really needs a pump atteched.

I simplified the construction of mine a little by leaving out the firebox stays as TC suggested, so far it hasn’t exploded.

Ceramic fibre and an inner liner of thin metal eg stainless. The ceramic fibre is far more efficient but fragile hence the liner. The spiral in the flue again could be just a strip of twisted stainless to cause turbulence, slow the gasses to aid heat removal to the flue.   Noel.

It has been stated several times that gas firing and multi tube vertical boilers don’t work well, but why? Plenty of gas fired loco boilers in USA where they have serious forest fire risk. Is it just that you need a forced draught with a multi tube boiler? If so that’s not difficult to arrange

I have seen fine stainless steel wire inside a gas boiler tubes and when lit it glowed red so perhaps the boiler was not so good without it fitted.