2” Bubble Cap Build
Posted: Mon Sep 08, 2025 8:34 am
I need a bubble cap for a 2” column, and I’m a cheap bastard with a pile of copper, so I made one. The parts list is pretty simple:
2” of 3/4” pipe cut and flattened into sheet
2” of 1/2” pipe
4” of 1/4” tubing
2x 1” caps
5” of cooper wire
Lead free solder
I started by drilling a hole in the sheet and flaring it to fit the 1/2” pipe. I then drilled 4x 1/4”’holes around that, and a hole in the center of one of the caps so that the 1/2” pipe would be a snug fit. Step drills are awesome for that. No snagging, and I didn’t even have to change bits for the three different sized holes.
To cut the notches in the cap, I marked off the spacing and the height with a sharpie, then used a file to start each notch. Then used a hack saw to cut down to full depth, and came back and cleaned up the center with the file. In total, I have 10 notches approximately 1/8” wide and 1/4” deep.
I cut the 1/2” pipe to length so that it was just a little taller than a 1” cap on the top, and a little shorter on the bottom, and then soldered it into place. I then cut four short pieces of 1/4” tubing, leaving one end of each piece pinched from the cutter. I pushed that end into each of the holes in the plate, then soldered them into place. I cleaned up the ends and then used a punch to open the holes a little. I also used the punch to tweak the top ends of the tubing so it laid up against the downcomer. I had to flatten them gently to get them to fit neatly inside the 1” cap, which I did with a small hammer. With that done, I soldered the cap in place.
2” of 3/4” pipe cut and flattened into sheet
2” of 1/2” pipe
4” of 1/4” tubing
2x 1” caps
5” of cooper wire
Lead free solder
I started by drilling a hole in the sheet and flaring it to fit the 1/2” pipe. I then drilled 4x 1/4”’holes around that, and a hole in the center of one of the caps so that the 1/2” pipe would be a snug fit. Step drills are awesome for that. No snagging, and I didn’t even have to change bits for the three different sized holes.
To cut the notches in the cap, I marked off the spacing and the height with a sharpie, then used a file to start each notch. Then used a hack saw to cut down to full depth, and came back and cleaned up the center with the file. In total, I have 10 notches approximately 1/8” wide and 1/4” deep.
I cut the 1/2” pipe to length so that it was just a little taller than a 1” cap on the top, and a little shorter on the bottom, and then soldered it into place. I then cut four short pieces of 1/4” tubing, leaving one end of each piece pinched from the cutter. I pushed that end into each of the holes in the plate, then soldered them into place. I cleaned up the ends and then used a punch to open the holes a little. I also used the punch to tweak the top ends of the tubing so it laid up against the downcomer. I had to flatten them gently to get them to fit neatly inside the 1” cap, which I did with a small hammer. With that done, I soldered the cap in place.