Vertical Boiler Firebox Wrapper
by John
Next part to make on the 6″ vertical boiler is the firebox wrapper. I had ordered some 3mm thick 5″ diameter tube from the UK, but when it arrived, at vast expense, it was only 2.5mm thick, and would not pass the boiler inspection.
The vendor agreed to replace the item, but still no word when that will happen, so I decided to make the tube myself, by rolling 3mm plate copper sheet.
I calculated that I would require 399mm to make a 5″ tube, and bandsawed a piece off my 300x400mm sheet.
My hand roller is only rated for 1mm thick material, and my powered shop roller would not fit the 105mm width. So I tried the hand roller. It would not look at the copper strip in an un-annealed state. So I annealed it. Photo opportunity!
Too big for my “kiln” so it took longer, and lots of spilt heat. But it was a cold winter day again, so the heat in my workshop was welcome.
The 3mm thickness was a bit of a problem. The gears in the roller are really not designed to mesh at this thickness. But with a bit of gear jumping, and a lot of elbow grease, the roll started to take shape.
Re-annealing was required at this stage. Looking a bit rough.
Just love that colour
The wooden form gives exactly the final shape and size. Determining the longitudinal cut was tricky.
I determined the squarest end, rested it on the table, and bandsawed the mark. Then a bit of hand hammering. over the wooden form.
The foundation ring was machined to the final size yesterday. The outside of the ring fits nicely inside the boiler wrapper. And the firebox wrapper fits neatly inside . It needs to be OK’d by the boiler inspector before I silver braze it.
johnsmachines 