Brian’s Bokakob

[YHB]

To those who have not given column stills a thought, a brief introduction and explanation.

Liquid Management (LM) Reflux Columns work by managing the amount of liquid that is taken out of the still, this amount is small and needs to be controlled very accurately, typically the take off varies and has to be adjustable accurately between 1 to 4 drops a second. Valves that are available in the local plumbers merchants are not accurate enough to give this degree of control. The valves that are available off the shelf and can be used successfully for this function are “Needle valves”.

The valves because of their location in the still are subject to very hot, 95+ % alcholol and should be made from materials that are suitable for this environment. Off the shelf needle valves come in two materials, brass and stainless steel, brass tends to be frowned upon by the purists as it generally contains lead, stainless steel is expensive additionally you need to find one that has the seals made from an inert material, something like Teflon(PTFE).

What is needed is a copper valve – can't find one? - why not make your own?

On another forum someone suggested using a stainless steel bicycle spoke as the needle of a valve, the topic was discussed but I could not find anyone who had built one, so here is a brief description of my efforts.

I have two versions to try out.

Mark 1.







Apparently, one problem with the Slant Plates of a Bokakob is that there is a pool of distillate trapped between the lower slant plate and the needle valve. Experienced distillers using this type of collection system like to keep this pool as small as possible to reduce contamination of the hearts with any tails that may be prematurely produced due to incorrect operation of the still in the later stages of the run.

I had a play with the design and came up with this configuration which greatly reduces the amount of distillate trapped.







Re-thinking this set up due to earlier comments made by the Capt'n I am now thinking that the result of taking the condensate out of the still and back in again may result in the distillate cooling down too much and making it travel too far down the column before boiling again.

The valves are easily changed so I will be able to try both and see which one works best.

I have tried the valves by pouring water down the column and they seem very controllable with a range of 1 drip every 20 seconds to a very thin continuous stream.

Time will tell if they work in service but I am quietly confident that they will do the job and they are a lot cheaper than anything that you can buy off the shelf.

If anyone has experience of needle valves and has any comments or concerns about the designs then please feel free to comment.

[Capt-Cudellez]

Brian, I wish I had your skills and ingenuity - even with the cost of those fittings, compared to the cost of a good SS needle valve it's nothing - well done mate.

also your cassette is a very nice idea.

Btw I noticed the lower plate does not have a tab to direct the overflow go down the center of the column, rather that run along the underside and channel down the walls - haven't read up on these much - so just a casual observation comparing it to other designs I have seen, rather than a criticism.

cc

[YHB]

Thanks for the kind words Capt'n. - "skills and ingenuity" not really, only lots of time time. Lots of time to think about what I want to do, and lots of time to put things right when I screw up again and again.

One of the advantages of the cassettes is that they are easily removed. Once I had it in my head that I may want to use the standard valve configuration, I took the cassette out and added the drip tab that you mention. It took all of 20 minutes and was a lot easier than trying to bend the tab with a long screwdriver that you need to do with the permanent type of plates.

Thanks again for your observations and comments they are very well received - have a great Christmas.

[YHB]

Hello Everybody - I hope you have all been good boys and girls this year and Santa brought you some lovely presents.

My next item on my build program was a 2" boiler connection.

I have looked at 2” compression fitting tank connectors, I know many people have used them and I am sure they are happy with them, but:

a) In my opinion they do not look as though they will give much lateral support to the column.
b) I would have to buy it.
c) I would also have to buy some form of wrench(s) to install it
d) It is Brass, something that people keep telling me I should avoid.

So it seemed logical that I should make one in copper.

I do not have a workshop access to lathes, drill presses and the like or the equipment for silver soldering, I needed a build that could be made with my hacksaw, hand drill and rat-tail file, so I came up with this one.

The material all came from a 2 foot length of 2” pipe, that I split and flattened. The flange (4" Diameter) is made up of 4 ply of copper and the backing ring 2 ply. Still some cleaning up to do – but as I said, I have lots of time.










Making the bits was relatively straight forward - soldering them was a bit of a learning experience.

Apparently, what I should have done was use solder that had different melting points for the different joints. I used the same soft solder for all the joints and it took a few attempts to get it to this state. A few times I was trying to make the last joint when all the previous joints melted and the whole thing collapsed.

I find that working with Copper and solder is very forgiving, make a mistake, heat it up wipe off the old solder and start again - I would say to anyone that would like to have a go at making something in Copper "give it a go" - this is my first copper project.

[hoosier1]

I have been following along on this building of the Bokakob still and was hoping to get some questions answered. I would like to build a 3" X 36" Bokakob still. I'm not sure about some dimensions, does the coil have to be a uniformed length, do the slate plates line up in the middle of the column? Also, I built a 4" reflux that uses a mechanical controlled valve, does the Bokakob require any valve or is the coil water turned on and off manually?

[YHB]

Hosier - Welcome to the group.

I am very much a beginner when it comes to distilling but I have done a fair bit of research into the Bokokob design.

Here are a few sketches that were produced by the Samohon on the HD website, they hepled me get my head around the differences between Liquid & Vapour Management systems.






The sketch of the Bokakob clearly shows the slant plates overlapping rather than lining up at the center as you suggest.

I have never come across any details of automation for the Bokakob and yes the cooling water is controlled manually.

I have sized my coil to allow for future expansion but I could not claim that I know how to size one for a 3" Bokakob i would suggest that you have a look at this site - which is wealth of information just for Boks'.

http://wiki.homedistiller.org/index.php/Boka_Reflux_Still_-_How_To_Build

If I can help I will - just ask.

[YHB]

Cap'n C wrote
"That connector is great, if going down the stockpot route, have you given any thought to how you are going to secure the lid?
I have seen bulldog clips used for pot still conversions, but a long column is a different story. When the boiler heats up, you will get column ossilation, the column will act like a big leaver. If using a light clip, you may want to secure the collumn to a wall or roof if that is easily done in your stilling area."

Cap'n once again your guidance is much appreciated.

I have given lots of thought on how I am going to secure the lid, unfortunately I have not made any decisions yet. I have lots of ideas but which one I will use depends on the type of boiler / pot I end up using, so I will sit of the fence for a bit longer.

Thanks for putting my mind at rest. I have seen many pictures of stills that I have considered unstable, tall slender columns that appear to have very weak conections to the lids of pots that to say the least look very thin and flexible. You are the first person that has confirmed that it is an issue that needs to be addressed.

In my opinion the matter is made worse by long hoses that are often connected to the top of the columns, they appear only to need a slight tug or someone tripping over them to bring the still down. I may be a worrit but it goes with my training in a former life. I am convinced that if the goverment ever legalises home distilling the Health and Safety boys would shut them down the very next day just because of the hoses.

That little rant was only to justify my next statement, which is, I intend to hard pipe the flow and return lines to the condensers and parrot. I will make the service connections at the bottom of the column and run two 3/4" copper lines up to the top of the column.

I have it in the back of my mind to lace the column and these two lines together to strengthen the installation. And I have always accepted that I may have restrain the top of the column to the wall, now that you have mentioned the oscillation I will add it to list of must do items.

Thanks again

[Capt-Cudellez]

The oscillation is only slight, a light finger or a couple of bits of string would stop it. I'm more worried about any pulls or knocks - or even when just adjusting the valve, could leaver off the lid if applying some sort of sprung clip.

Its a balancing act - you want a lid that is secure, but I think it is also good to have a seal that wont put up with too much pressure in case of pressure build up.
Sometime when I run gin using the pot still head, I just un-clip 2 of the lid clips for safety - I could not do this with the column in place, as the little movements of the column are magnified, and the lid would leak vapour.

[YHB]

Bits of string - bits of strings, flour paste and paper clips - that is not me. I irrivocably and unresevedly appologise to everyone who successfully uses these methods and have been using then for years, but I like engineering, thats what I do.

One thing at a time, I am in no rush to start operating this still I am enjoying the build, the learning experience and chating with like minded people. One of my main problems is that - I am spacially challenged - once I have built the still and start brewing I will have lost my build space, so I want to eliminate as much rework as posssible.

I am anticipating that the lid of the boiler will be reinforced to limit movement and held on by some form of screwed clamp arrangement I have a couple of schemes in mind, but waiting for the right boiler or materials to turn up, and then seeing if I have enough headroom to fit in a nice beefy stainless steel dome cap to the boiler (if I can convince my wife to part with the salad bowl that her favourite Aunty gave us as a wedding present)

I will not be relying on the seal on the boiler lid to fail as a safety feature. I will be adding something hopefully a slightly better engineered, I do like the idea of making a rupture disk from Aluminium foil ( or is that just a glorified cork? ) and as I said to you in your post I am thinking of a pressure switch to cut off the power supply.

I will watch your thread and see how your safety feature goes.

[Keystone]

YHB,

Great thread. Your build has encouraged me to build one. I'll likely do a couple of farewell runs on my SS super reflux using a 2 inch nominal copper pipe at 36 inches long as an extension while I am sourcing all the bits for the Boka..

[YHB]

Welcome aboard.

If there is anything specific that I can be of help with then please let me know.

Don't forget there will be lots of people wanting to know how you are getting on. So keep us all posted with lots of pictures.

[YHB]

Having made the tank connector, I now needed to connect the connector to the column.

There are a few off the shelf solutions. If you are looking for a permanent solution then the easiest way would be a standard 54mm Yorkshire type soldered connector these vary between £15 and £20 per joint. I want to be able to remove a 1 meter section from the length of the column to detune it for stripping and maybe pot-stilling in the future, for this I need two demountable connectors. The home distillation fraternity seem to have adopted the cloverleaf clamps and easy flanges as standard, these work out at about 60 USD per joint – carrying on with my philosophy of why buy it if you can build it, I opted to make a couple of slip joints – the material is all from 54mm stock tube and it takes about 16” (400mmm) to make one joint – at today’s prices that works out at £7.50 a joint.

The commercial clamps should guarantee a leak-proof joint，my slip joints are a bit of an unknown factor but if I was a gambling man I would bet that these joints will be just as leak free, time will tell.

The first Sketches are something I knocked up for discussion purposes with a couple of mates.








These are obviously pictures of the joint - the second one looks neater.













It's getting there!

[YHB]

I had a day free yesterday so decided to have a go at some plumbing and install the coil into the Column.

A few pictures to be going on with

The coil looks as though it has been in a few fights. It used to be as a snug fit in the column, a bit too snug, when it got three quarters of the way in it started to bind.

I put the coil back into the mandrel and went over it with a toffee hammer to make it a "bit smaller". It seems a shame after going to great lengths to keep the tube round when I was making the coil. But the result is worth it, it is now a nice sliding fit into the column.

[Capt-Cudellez]

Thats looking really sharp YBH - what size of pipe is the coil - 8mm? 6mm?

[YHB]

2 x 8mm coils + 15mm cold finger = 47mm which does not leave much room for gaps.