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I love my potstill, been using it for many runs and recently removed the thumper and like it even more. I like to build things and tinker, now that I am happy with my potstill, it's time to make something else to play with.

I recently stumbled upon a couple 5 foot sections of 2 inch copper pipe - one thin walled, one thick. A pipe supply house had some 20 foot sticks that got run over by a truck and I was able to get them for $35 a piece

I decided to upsize a Bokakob Mini eliptical plate still and was doing some simple math. The original design uses 24 inches of 1.5 diameter, so if my math is correct, I should start with 32 inches of 2 inch. I have read a bunch of posts here and some folks say 30 inches between the take-off tube and the bottom. That makes the total length about 40 inches

I just want to know what has been improved upon since the original design - is the still more stable at longer length? Is thick walled pipe more stable than thin? Is there a length that is considered overkill? I would hate to cut 28 inches off of a nice length of pipe only to find out that I should have used more..

I am leaning towards a total length of 42" - 7" for condenser, 2" for plates leaves me 33" of packed column.

Suggestions?
Advice?

Thanks in Advance.

I have got a 2" mini still, just a few inches longer that specs and it works fine.
Without trying to sound like I know what I am talking about, cos I have only been at this game for a few months (but seeing that no-one has answered), here is my interpretation of the column.
Considering that this type of still ,as well as being a reflux still is a liquid management reflux still, therefore,
1) The length of the part of the column containing the scrubbers is not overly critical as a lot of the purity comes from how much of the distillate is returned back down the column for re-vapourising - but a bit more room for a few more scrubbers would not go astray.
2) If going 2", you will be able to use a much larger heat input (up to 3400w) in which case if you are going that way, you would be well advised to use a larger condenser to enable that heat to be knocked down to condense the increase in distillate production.
So - I would say that if you were going to make it any longer than 3ft or 3ft 6, what were you planning to fill in the empty space with?
Reflux or cooling?
Any-one else, please jump in.

I will be adapting the column to my existing boiler. I have a 15 gal keg with the top cut off and a threaded flange on top of a stainless steel bowl. I can unscrew the potstill head and screw on the Bokakob

I have two 2000w electric water heater elements - one is on a rheostat. I use both to get her up to temp and use the rheostat to control my output.

I have plenty of power so I guess I should probably fill the empty space with cooling.

I appreciate the feedback.

Nice price for 5' sections.

If you can get the fittings, then go with the thick walled pipe, much tougher. Measure the outside diameter of the two different pipes. The thick wall will probably be slightly bigger than the thin wall. Thick wall is used in the air-con trade, so check the air-con trade suppliers for fittings for the thick wall pipe.

Basically, the height of the column (specifically the height of packing section) in a reflux still, is what determines the purity, and the diameter determines the maximum output rate (for a given purity, and reflux ratio). But more packing height allows you to run a bit faster output rate (for the same purity).

So, 33" of packing will give you a pretty good result, but more packing is better. If you can fit the height into your stillin area, then use the full 5' piece. I have 59" of mesh packing, and get a very clean product.

A good coil condenser around 6-7" should knock down the power levels used easily. You do not run a reflux still flat out after you have got it boiling. Typical power input after boil up is 600-1000w.

My 2" Bok is 34 inches high with 24" of packing. I'm pretty sure those were the numbers Bokabob recommended, when I asked him about scaling it up.

Works fine, no problem turning out 95% at a reasonable rate. Taller is always better, but I use it in the house on the stovetop so I wanted to keep the length reasonable. If I had plenty of pipe, and wasn't going to be using it in the kitchen I'd probably go 6"-12" longer.