Small bubble cap plates

[invisigoth]

hi guys and girls :)

as far as i can tell, i haven't seen any small bubble cap plate builds. I decided to take this on. i must have been planning this for a couple of years and forgotten about it. i discovered i had all the necessary tube and 6 flat pieces of 0.8mm plate a bit bigger than a plate already cut :o .

first step was to screw the 6 pieces of plates to some plywood and drill the centre hole and 5 outer holes with a 16mm hole saw:



the bulk of the excess was trimmed with a cut off wheel on the angle grinder, then finished off on a disk sander:



next i used a pipe cutter to cut 30 lengths of 16mm tube for the risers:



the aria around the hole on the plate was cleaned up with a stainless wire wheel on the dremmel and supported the riser with some metal plate to get the height right:



and then welded:




when i was making my boiler i had brazed some copper plate to a hammer face and a dolly. it was then that i discovered that it was not difficult to get copper to melt with the tig if you got an edge. welding was tricky because once the puddle forms it's very easy on the plate for the tig torch to become a plasma cutter :scared-eek: . i wrecked one plate, so this became my guinea pig plate. i discovered i had some solid core copper wire, so this became handy for fixing things when they started to get out of hand. on the guinea pig plate i tried to silver braze a couple of risers with 2% and 5% with MAPP gas, but something was acting as a heat sink and I just couldn't get it to flow.

next was starting to make the caps. i started with some copper sheet and 1in tube cut to length:



brazed from the inside with 2% silver:



and soaked it in vinegar :



this is how it came out:



not exactly pretty, but later after I did the slots they were soaked in citric acid and that cleaned them right up :-D . for S&G i decided to try welding one cap:



a habit i picked up from building a canoe, i made a jig to cut the slots. 6 caps at a time, two slots per cut with a circular saw :



sadly i'd quenched the caps after they were brazed, so the copper was annealed.this bit me in the bum during the cutting:



it was pretty tedious having to pull the 6 out after each cut, re-shape the cap with a pair of mig pliers, put it back into the jag turned a bit and on with the next cut. the finished cap after a soak in citric:



the weir for the down comer was brazed on :



and i used 15% silver braze and the tig to secure the caps to the plate:



the finished plate :whistle: :



:laughing-rolling:

while I was cutting the slots i had an idea, which will be in the next post .

[invisigoth]

so, while cutting the slots i had a couple ideas, so i made up 2 more blank plates with 6 16mm holes. the idea starts like this:

stage 1, 16mm tube brazed with 2% to some copper sheet:



then holes drilled similar to the 5 star risers:



and two different versions of the 1inch cap brazed from the inside with 5% silver braze :



the weir and down comer were brazed to the plate at the same time by brazing from the inside. the rest of the caps were soldered to the plates :



my soldering skills leave a lot to be desired, and despite making sure everything was clean and using ample flux, i was having difficulty getting the solder to wet out properly all the way around. somehow i managed. and the finished plates:



anyone have any ideas about the plate with a space instead of slots? would it still work, or are the slots required to create more surface aria of the bubbles?

[db1979]

Nice work :handgestures-thumbupleft:

I think the non-slotted caps will only allow big bubbles to form and you won't get the benefit of the interaction of the vapour interfacing with the fluid. My guess is you'd have less flavour carry through.

[woodduck]

Nice work on the plates mate. I'm with db here, not sure those caps will work all that well but who knows they may be fine. Only one way to find out.

[scythe]

The cross drilled riser will work, it is cap that determines bubble size.
The slots will split up the bubbles into smaller ones.
Might be able to save them if you notch to cap a bit.

Also next time you cut slots for caps with a table saw find a way to cut them before you solder them to plates, they will still be "hard" so should deform less.

1 more point to consider for next time, think about a weir on the top of the plate to help with setting a liquid bath.
Could maybe soft solder a short ring of 1" to the top if you find that your plates dont hold a bath?

[Ravvin]

In regard to your issue with the copper being annealed, making it soft and easily deformed when cutting, you could try to re-harden it before slotting it.
All you need to do is heat it to a dull red, (hard to tell with copper), and let it cool slowly. We used to increase the cooling down time by dropping the heated item into a container of brickies lime. This insulated it and so it took a lot longer to cool down, making the copper harder.

You mentioned you used a Dremel to clean up the copper plate. You can get a toothed slotting disk for Dremels that would put less pressure on the copper tube. Also, being small diameter, you could slot from inside the pipe, working out. That way the fingers that are left would be supported by the timber in your jig.

Greg.

[invisigoth]

The cross drilled riser will work, it is cap that determines bubble size.
The slots will split up the bubbles into smaller ones.
Might be able to save them if you notch to cap a bit.

Also next time you cut slots for caps with a table saw find a way to cut them before you solder them to plates, they will still be "hard" so should deform less.

1 more point to consider for next time, think about a weir on the top of the plate to help with setting a liquid bath.
Could maybe soft solder a short ring of 1" to the top if you find that your plates dont hold a bath?

<sigh> nobody actually reads these posts, do they? it clearly says "the weir for the down comer was brazed on". the first plate i did it was soldered on after the caps were anchored. soldering proved to be a bit clumbsy for me, so the rest were brazed from the inside as shown in the pic. all 5 welded plates add the two "i have an idea" soldered plates have 18mm high weirs.

for the plate with the slotted caps the slots were cut first before brazing to the cap plate. went well for the first two passes. on the third pass the saw plucked one of the tubes out of it's hole and into the guard of the saw. The saw survived, the blade survived, the tube for the cap was crushed. the jig was a good idea poorly executed.

the plate with a gap instead of slots was just an idea, not intended to necessarily be used.

[invisigoth]

In regard to your issue with the copper being annealed, making it soft and easily deformed when cutting, you could try to re-harden it before slotting it.
All you need to do is heat it to a dull red, (hard to tell with copper), and let it cool slowly. We used to increase the cooling down time by dropping the heated item into a container of brickies lime. This insulated it and so it took a lot longer to cool down, making the copper harder.

You mentioned you used a Dremel to clean up the copper plate. You can get a toothed slotting disk for Dremels that would put less pressure on the copper tube. Also, being small diameter, you could slot from inside the pipe, working out. That way the fingers that are left would be supported by the timber in your jig.

Greg.

Good idea with re-hardening... but the heat might melt the braze. dremmel? erm... fine for a few large bubble caps, but when you have 30 caps to do, that's just tedious! and the slots a bit too small i think... faster with the angle grinder, but the idea of the jig was to get two cuts done with each pass, and an entire plate set. of course the logical thing to do for those non-masochists would be to just buy the 5 star plates :)) . they are sturdy, consistent and nicely machined. 8-} i just hadn't seen any posts with small cap plates diy-ed .

[woodduck]

I did small caps on the glass duck. There is some info in the build thread I did.