2” Bubble Cap Build

[Steve Broady]

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

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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.

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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.

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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.

[Steve Broady]

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Because of space limitations in my column, I had to trim another 1” cap down slightly. In order to suspend it as a trap, I drilled a couple holes in the bottom and soldered some copper wire in place. The wire just goes up through the downcomer and is bent over at the top, making it easy to remove the cap if I need to.

The last bit of work was to drill a 1/16” hole in the bottom of the trap, and another in the plate. My hope is that they will be too small to impact operation, but will allow the plate to drain once I shut the still down.

Here’s the finished product:

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I know it’s just another bubble cap, nothing particularly special or innovative. But it was cheap and quick to make with only basic tools, and I figured nobody would mind me sharing.

[Yummyrum]

Nice work as always Steve

There really is a thrill in being able to rummage through the scrap bin in your garage and whisk up a piece of equipment .

[Steve Broady]

Nice work as always Steve

There really is a thrill in being able to rummage through the scrap bin in your garage and whisk up a piece of equipment .

Thank you, sir! You’re right, it’s satisfying. I know they’re not expensive, but free is an even better price. And I was able to make it fit my needs.

[Corn Cracker]

I have the stuff to make that, and thats my problem I've got a nice scrap pile and wanna make all sorts of stuff i see on here

[Corn Cracker]

How many of those do you need in a column?

Nice work btw

[Steve Broady]

How many of those do you need in a column?

Nice work btw

Thanks, CC. In my case, I only need one. I’m using it as a heads training a continuous column. But if you wanted to make a small plated still for batch running, it seems like most folks are running between two and four plates.

[Corn Cracker]

I've bookmarked this for future reference, like I said, I've got a bunch of materials and a gazillion build threads left to go through, thats a few years of digging around in here already.

[shadylane]

I think the cup needs to be a little deeper than it is for the plate to load easily.
It's close as is but a little deeper will work better.

[Steve Broady]

I think the cup needs to be a little deeper than it is for the plate to load easily.
It's close as is but a little deeper will work better.

I tried to account for that by making the notches deeper. My thought is that the height of the cap isn’t as important as the depth of the liquid that the vapor is bubbling through. If I got the build right, the liquid above the notches should be just a hair less deep than the trap.

No guarantee that I’m right about that, but that’s what I was thinking.

[Steve Broady]

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It turns out that the 1/16” weep hole was too big, and the plate would not stay loaded. No great surprise. I’ll put a piece of copper wire in there to restrict the opening.

But even so, it was holding up a little liquid and happily bubbling away. I can and will do better, but it’s not a complete failure.

[Yummyrum]

I missed that you had a weep hole . I remember a member trying that here over a decade ago now and found the same . Back then all the plates were on slide in types and I was amazed that even though there was in some cases significant leakage around the plates nit to mention all the holes in the seive , that a tiny drain hole in a down comer cup would fail the while plate .

[Steve Broady]

What do most folks do about the liquid that stays on the plate or downcomer trap after a run? Just let it evaporate? It seems like you’d want some way to drain them after a run.