You should be fine just silver soldering them into place (C)

 

As they are quite small its not reallly worth profiling the back to the barrel radius, the solder will form a fillet that will fill any slight gap

 

J

Hi Bill,

 

I’ve just completed the same boiler, also my first attempt at boiler making, and I did as Jason has suggested, just drill a hole in the boiler, pop in the bush and solder. The only bushes that caused me concern before I soldered them in place were the pair of water sight glass bushes. These obviously have to sit in identical alignment otherwise the 2 sight glass pillars will be out of alignment making it impossible to fit & seal the sight glass.

 

Rumaging through the scrap box I found a piece of brass rod of slightly less diameter than the boiler bushes. I prepared 2 pieces each about 1″ long and threaded one end of each 1/4″ x 40 to suit the internal thread of the bushes, the other ends were faced square to identical lengths from the bush flange then drilled & tapped 2BA. A short piece of 1/4 x 1/8 flat bar was cut to length about 1/2″ longer than the centre distance of the 2 sight glass bush holes in the boiler. A 2BA clearance hole was then drilled at either end of the flat bar at centres equal to the boiler bush centres. The 2 previously prepared “pillars” were fixed to either end of the bar with 2BA bolts & the 2 bushes were screwed onto the other ends of the pillars. I now had a little jig that would hold the 2 bushes in perfect alignment whilst they were being silver soldered into the boiler! Seasoned boiler makers will probably say I was being over cautious but it didn’t take long to make and worked a treat!

 

Regards, Martin