Concluding the day's posts: I needed to make a couple of 1" BSPP (G-thread) x 3/4" copper sweat adaptors that will form the ends of the heat exchanger tube and make the seal with the boiler plate. These are necessarily custom parts as this they adapt from European to North American standards. However, I think that is it reasonable to consider the HX tube as a non-serviceable i.e. a custom part.

Lead-free hex stock after threading, chamfering and cut-off operations.

View from the other side showing the 90 degree included-angle internal chamfer that will seat and seal with the hemispherical "bi-cone" fitting.

The part is flipped and bored to receive the 3/4 copper pipe.

Test fit of the pipe.

Group cap sandblasting

I got access to a sand blaster and put the group cap with the off-colour chrome in it to see what would happen.

The hard metal comes off fairly easily revealing the copper layer underneath. The image is a bit pinker than the real thing.

Frame part 1 - raw materials

Getting metric rectangular tubing seems like a foolish endeavour, so this part of the project will use North American standard materials. I got a 20' length of nice 1/2 x 1 1/2 x 0.065" wall tubing 

Also, 12' lengths of cold-rolled 1018 steel in 3/8" x 3/4" and 3/8' x 1". Working 1018 is such a pleasure after wrestling with that stainless!




Cut to length and cleaned up. A few more things to do here before they can be welded together...