Started to braze with silver solder to put it all together now. Bit rusty at first and made some stupid mistakes but the skill is coming back to me a bit faster than the first time I learned to do it.

This is the funnel off the jug I have been recycling into the top of the bubble ball. Cut it in half across and used the bottom bit to make a bottom for the top bit so I would have a reflux redistribution tray to drop the reflux from the column to one side of the bubble plate. The downcomer goes on the other side so the reflux flows across the plate before exiting back to the boiler.




Here is the finished tray ready to be brazed to the underside of the top of the bubble ball.


Here are the stages of adding the outlet pipe for the column to attach to.
First of all butt brazing the RJT fitting to the end of the pipe. A clamp to hold it while I get the first tack brazed on. Then braze around, grind it down, Check for leaks, rebraze, rinse and repeat. Took three runs around before it was leakproof. My first braze in some years. Solid as the parent metal though.

Then slide the nut over and braze it into place on the top of the ball.

Brazing the sight glass fitting into the stainless collar that forms the middle of the ball.

Bubble tray drilled out. Top hole spaced differently to the others is for the downcomer which I have made and fitted ok but not got a pic at the mo.

Totally rubbish first attempt to attach the top of the ball to the collar. Tabs are too large and it was drinking gas and silver to produce an ugly, ineffective, joint. Don't do this at home.

OK, trimmed the tabs down and made much less of a pigs ear of the next attempt.
After getting some tabs brazed on around the rim I debrazed and trimmed those ugly first tabs. Very hard to cut through any solder on the copper. Had to do them hot. Strong stuff. Not done the lot yet but happy it will go ok and be leak proof with minimal use of silver and gas.

The underside showing the reflux tray brazed in. It is only attached at the left hand side. There is space above it for the vapour to pass easily.
I have seen people ask about using gauze instead of slots on bubble caps. They were always blanked with no reply at all that I have found. I take this to mean the answer was unknown to the people being asked. So I tried a little experiment using some 30 mesh stainless gauze scraps I had.



I used a bit of welding wire and some tape to seal a gauze skirt around a 28mm cap. Stuck it in a jar with some white spirit (all I had besides water) Blew air underneath it.
Could see the air displacing the white spirit down the inside of the gauze. Bubbles came out from the gauze but only really at the top just underneath the edge of the bubble cap. Also mostly from the edge that was slanted highest. Seems to work though. 30 mesh might not be the best size to use. Something a little more open perhaps. Is what I have though. Main reason for using it is just to raise the caps a little higher to run with a deeper pool to bubble through.If it only comes from the top with ethanol as well then maybe there is no point as not getting more liquid vapour interaction from the bottom to the top of the pool. Will ponder some more before committing to an upcomer design.
Went and took some more pics so here is the tray with the downcomer in place.

