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2.5" (formerly known as 3") Bubble Column

This discussion was created from comments split from: New 5" SD Stuff.

I've been toying with the idea of a 3" Dash. Targeted mainly for use with a 20 liter (5 gallon) milk can. I strongly suspect that stove top size is more than adequate for booze self-sufficiency as many folks still do 5 to 6 gallon ferments. In all truth, 2" is too small, 3" a bit big and 2.5", although the ideal size, is too oddball because of the investment needed to support it with the full range of reducers, clamps, custom gaskets, it's own 2.5" dephlegmator, etc...
We already have the complete line of 3" reducers, tees and stuff so it would be quite easy to develop if I received any positive feedback suggesting an interest.

Edited by @Moonshine: Discussion title changed to reflect the new direction towards the 2.5" column tech.


  • Lloyd no one has a 3" bubble cap still that i have seen ... an open market for that size...

    I spent some time looking around found a couple builds here and there but nothing built on a commercial level for the consumer..

    In three inch would it be the std. bubble caps or one large bubble cap and a downcomer?


  • Priced as inexpensively as possible this would be a great entry level size bubble capper...

  • I bit down and ordered 2.5" sample ferrules, gaskets and clamps yesterday because that is truly the optimum size for what I have in mind. Really just need those samples to confirm measurements and see how the plate would layout.
    This may, or may not, be a stupid idea to pursue. Custom gasket molds cost about the same for almost any size and I can't think of a way to make a cheaper shotgun condenser. For the dephlegmator a 2.5" about like the big baby but the product condenser? The 180 bend? Can't make the parrot any cheaper either.
    This is not a pressing project, just an idea that keeps rattling around.

    A little SD StoveTop still would be kinda cool though.

  • with the 3" i kinda saw three caps and a downcomer fitting in tightly... little room to spare... i mean you could trace it out on paper and get some caps and lay on it to see if the circle would be large enough etc... to fit the caps and downcomer inside...

  • Just my opinion but the 3" size would be a practical build with a single large bubble cap. You still have the issue of the downcomer, but there are ways around that too.

    There is not a lot of space inside a 3" and this might be one of those times when you want the plate layout to be as simple and uncluttered as possible.

  • You occasionally see posts on some of the forums (mostly related to packed columns) where the column does not work because it is too BIG for the boiler. You get to a point where the volume of the column is too big for the amount of volatiles produced by the boiler charge. Especially if you charge with low ABV wash.

    Now I have never tried to calculate it, but you can imagine a situation where once you have loaded the plates, and filled the column with vapour, that you might have depleted the volatile charge from the boiler. This might be unsustainable.

    Does anyone know how big a column can be supported by a 20 litre boiler? Or extrapolate it from experiments on a keg boiler.

  • Something new on the SD horizon that's in development for the 5" and planning to use that for the 3" plate system IF the 3" size column is something that your distributors want to stock.
    They will probably want run data, costs and interest from you guys before showing any interest themselves.
    For now, just testing the water to see if there is any interest. And this is probably the worst place to ask because most folks here have much bigger stills already.

  • @LOO, you used to run 6" stuff on a keg. Did you ever put more on than the boiler could sustain?

  • Why wouldn't you just use the 3" size for the tower and reduce down to 2" for the condenser, much like the 4" towers reduce down past the defleg.? Except for this size you could use the 2" size for the defleg as well.

  • I have long wanted to create a cheap stovetop still for Grandma to make her own toddy.
    The column is not a problem at all. A cheap 5 gallon boiler is hard to source unless I can modify a stockpot. No element port needed since it is stovetop but the lid needs to seal well and have a ferrule port. The lid could be hard to source cheaply.
    The condensers cannot be had cheaper than we are getting now and I'm not fond of liebigs.
    The cheapest solution is the Crystal Dragon and I figure Gramps needs 4 plates because she likes her toddies on the clean side.
    An end cap reducer instead of the sight tower ends would further reduce the costs and one end could be a different clamp end than the other to eliminate a reducer.

    The simple truth is the average homeowner does not need the capacity of a full-blown 4" Dash. Grandma needs something she can sit on her stove next her pot of dumplings.

    I figure Granny does not need the expensive parrot with her kit but would appreciate a measuring cylinder that had a alcoholmeter.

    Everything should fit inside of the stockpot for shipping. A complete kit.


    Interesting to note, a 2" baby dephlem could fit between the clamp ends as the OD of 2" just might work. That saves a bit.

  • I know that ages back when minime was doing some stuff he used wide brazier pans instead of stockpots. IIRC these are only 6" high which is good as vertical height can be an issue - especially if you have a hood over your stove.

    You might be able to save a bit more height by using a cap or 90 degree bend at the top instead of the curved bend.

    What sort of height does the assembly work out at - without the boiler?

  • No idea yet as this is all still conceptual but I'm thinking the CD rods will be a problem to ship inside a stockpot.

  • Perhaps this is 1 application where it would actually be of benefit to make up 2 or 3 plate CD modules, each of which ends in a tri clamp ferrule. That way it could be broken down into easy sections for transport.

    Or just put threaded connectors at the mid point of the CD rods.

  • It's true, a ready-made 5 gallon boiler is surprisingly hard to find. I was looking around for one for a stove top rig I'm putting together for a friend. I thought they'd be common. One is available that is a stockpot with a 3/4" NPT male bulkhead fitting as the column connector. The lids are too thin for welding. Larger SS bulkhead fittings are quite expensive. It would be nice to find a milk can style with a 2" ferrule.

  • @Lloyd

    Could you find someone that makes a pressure cooker and have the factory that makes it modify it to have a tri-clamp fitting on top? Gives you a sealed vessel and they're usually large enough if you find the bigger ones.

  • I hope to see a 3" Crystal Dragon. Not only as a kit. I would like to be able to buy the individual pieces to make my own hybrid.

  • Pressure cookers are always a bit pricy and, not that it really matters but it does matter to some people, they are mostly aluminum these days.
    One option that we are exploring is using a standard 20L stockpot and having a custom lid and bandclamp made - much like whats on my personal SS conical fermenter.
    No doubt the lid and bandclamp will cost more than the pot. We're still working our way through this.
    Another option is to locate a factory that specializes in producing stockpots and see what they can do for us.

    Getting past the 5 gallon boiler as economically as possible would be a big step since the milk cans are really expensive for this small size.

    ...And then Wendy just now finds this... ooo la laa...


    Not wanting to get our hopes up because it may be too thin to support the little column or have a ferrule welded to it.

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  • edited April 2014

    Time to invent a ferrule adapter then. Screw in fitting in stainless with a locknut on the bottom, two silicon gaskets and a 2" ferrule on top.

    People need them. [-(

    Make LoO draw one instead of picking on me all the time. It'll keep him busy =))

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  • You could add a larger diameter support plate with the ferrule built in the center ... to stop the flex in the lid if there is any... and move the load out to the edge of the sealed top...

    Good looking small pot... temp gauge or themo port could go in the ferrule support plate as well.. ?

    Heck they would make nice small sealable fermeters/product storage... as well if their price was affordable..

  • @punkin said: Time to invent a ferrule adapter then. Screw in fitting in stainless with a locknut on the bottom, two silicon gaskets and a 2" ferrule on top.

    No need to invent them, they are already available...
    We just need to stock them if there is interest.
    This 3/4 TC x 3/8 NPT male thread is being produced now, should be ready in a week or so.
    Can be made in any size but they are made to order so a minimum of 100 pieces need to be made for each size. Which also means we could alter the design if we wanted to.


    Now there you go @FullySilenced :)) I'm fighting to keep this as cheap as possible and you are adding features. The thermowell ain't a bad idea at all! You recon Granny will spring for the extra 20 bucks for it?

    I might need to visit this factory. They have stuff!!


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  • I looked at these because they are only 6" high,19.75" dia and are 30 quarts. There are many other alternative brands available. For a range top boiler I think this is a better shape than a stockpot. It would be easy to have a new lid pressed in heavier material to support the weight of the column.

    As for those taper thread adaptors I have one of those in a 2" size. Can you get them with a parallel thread and the matching back nut?

  • edited April 2014

    You're right @Myles, height on a stove top is limited, I may need to keep digging for a more squat model.
    I'm sure I could get the fitting made; not sure we'll sell 100 of them. But then, 2" is a very popular size for many small stills. How many do you need?

    Another option could be modifying 4x2 end cap reducer to become a mounting adapter. A regular 4" gasket would make the seal if the lid surface is flat.


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  • Lloyd in the looney bin page 4, you showed some table mounted columns. What size was the one on the right, and do you have some 2" table mounts hiding in a box somewhere? Or were they 1 off specials in that picture.

    What you proposed above would certainly work so long as the lid would take the weight without bending.

    Off course you could use LONG bolts so that they reached the bottom of the boiler to support the column. :))

  • Myles, that's just a sight tower flange. A pair of those and some glass and it's pretty much a Crystal Dragon. But they are quite thick and heavy and have been machined to have the gasket in a recess. They are drastically over-built for our use. Really, the best way is to get the pot factory to weld on the ferrule.

    The strength of the lid is very much in question as the factory tells us that the pot and lid are standard at 1mm thick. That's OK for the pot but maybe not for the lid. They swear the lid can handle 20Kg stacked on top of it but I doubt that load was centered on 2" in the middle and hanging a condenser to one side.

    I want to make this as inexpensive as possible but no-one wants it falling on Granny.
    Tan couldn't quite get her head around the project so I asked her where in our small apartment we could set up a 4" Dash. She said "NO WAY!!", of course, and I reminded her that so many people, like us, just don't have the room for a big still... that everything must be able to store into the pot so it could be put away when not in use. I think she's on-board now.

    We asked about squatter style pots to reduce the height and they started talking special order (mold fees and high minimum quantities) and I got busy with something else while I lost interest, for now.

  • edited April 2014

    Hey Lloyd - Just a quick note on those mini-tc 3/4 flanges - you need to use rigid teflon gaskets, and not soft silicone.

    I use similar flanges for our alcohol transfer pump, and the silicone gaskets will distort so significantly the flange connections will leak. I know because I had Larry send me a couple of 3/4 silicone to replace the ratty looking teflon ones we were using. They are too small to compress in a consistent fashion. One or two turns on the clamp and the flange quickly goes misaligned and leaks. Ended up driving up to McMaster Carr (for those not in the US - they are an industrial supply recognized for extremely high prices (rip off even) because they know if you are there, you really need it) to pick up a handful of teflon ones at about 20x the price.

  • @Lloyd - ditto on the 3/4" being switched to teflon, the silicone wiggles too much.

  • Perhaps the issue is the use of the stock pot.

    You could use a 30 litre keg instead and just fit it with a bigger triclamp ferrule. Say a 4" or 5" so you could get all the column bits (except the short adaptor) inside the keg, through the bigger ferrule.

    Plenty strong enough and leak proof, run on either gas or an immersion element and it might be more readily available than the equivalent milk can.

    Or how about a 30 litre pot belly boiler? :))

  • Thermowell or just a 1/2" half coupling to put anything in... thermometer... thermowell etc. the time to do it would be when the screw-in ferrule is installed or welded on..whichever is more cost effective

  • @Myles Would a keg sit flat on a stove top burner?

  • I am dreaming of a small still, fitting on my induction stove, NOT made of aluminium, very simple, and of course cheap. I don't think a keg would do, first I think it is not beautifull (yes, typically said by a woman) and I would not like to have a gas burner, if I already have a induction stove. So some kind of pot would be the best solution. Or simply the top, which can be put tight on any pot of normal size, perhaps, we think too much of the whole thing, when parts of it are enough.

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