Brian’s Bokakob

[YHB]

Introduction
My name is Brian and yes I am from Yorkshire, that’s all you need to know.

I suggested that a "Build your own Forum" might be of interest. So I will start the ball rolling with my build to test the waters and see if there are any other builders out there that want to share.

Here goes;

I like making fruit flavoured vodka based liqueurs / infusions and wanted to find a still that would produce high quality, high % ABV alcohol. The only whiskey / brandy type drinks that I intend to make will be by using essences from the local brew shop, as such, I have no real requirement for a still that carries flavours from the wash into the distillate.

I have done a lot of reading and looked at many designs available and decided that a reflux column was what I was looking for.

At the moment I am one of the statistics of the economic downturn. As a result I have time on my hands but not much disposable income, so I decided to build a still, doing as much of the work myself as possible.

I looked at the various column designs and opted for a Liquid Management (LM) type as there is a lot of information available for building and operating these devices. I considered cost, material availability, my capabilities and workshop facilities which are strictly limited to a hacksaw, round file, hand held drill and a blowlamp.

After weeks of reading, research and indecision I finally committed to build a 50mm (2") x 1200mm (4'-0") packed length, Copper, In-line, Dual Slant-Plate, Single Column with a double coil / cold finger condenser, as designed by Alex Bokakob – I have a few variations that I intend to incorporate, some of which are due to substitutions from American to UK availability, others are purely Bling.

For anyone who has not stumbled on this already, this link will take you to a very definitive resource for Boka’s.http://wiki.homedistiller.org/index.php/Boka_Reflux_Still_-_How_To_Buildit gave me a lot of confidence to start making mine.

I am sharing this to show you what I have done, how I have done it, to try and demonstrate that it is not rocket science and to encourage you to have a go - if I can do it, so can you.

If you can add anything to my posts, please do so.

[YHB]

I don't get the point "not bad for a first post"

Yorkshire is a big place, and I thought this site was about sharing information about stills and distilling, why would I not "spill the beans on how to make a still" in forum called Build Your Own?

[Capt-Cudellez]

Brain, I have enjoyed several of your posts over on AD, and look forward to see how your build progressed.

Your "cassette" column insert idea, i have not seen before, and i really like the concept.
Looking forward to more posts.

My current project list that hopefully I'll be able to share in this section over the coming months are.

30gal Copper boiler to be made into a dedicated 6KW pot still for rum and whiskey.
3" Stainless Vm\RLM combo, with offset condenser and external reflux return.
Add a sight glass to my 50L keg stripper and swap out the 3Kw for a 4.5KW element.
Mod my T500 boiler to have pressure relief.

[YHB]

Condenser Coils

I had no experience of working with copper and the thought of winding condenser coils was off-putting to say the least. I decided to make the coil first, using the logic that if I failed to make a coil then I had not wasted the effort and cost of making the rest of the still that would be useless without the coil.

I am now addicted to making coils – it’s relatively easy, entertaining and satisfying. They are very straightforward and if you follow a few simple rules turn out well and when you polish them up they are very impressive.

A lot of the instructions on the web are American and based on a double coil, wound in one go. Unfortunately they seem to use a size of copper pipe that I have not been able to locate locally. The nearest I could find was 1/4 “gas piping from caravan shops.

I eventually opted for standard 8mm copper tube, sold for central heating that I can buy at the local plumbers for £3.00 a meter. Unfortunately, I cannot get this larger / thicker material to bend to the shapes required for a double coil, so I had to use a different configuration.

5m is more than enough to make a large condenser for strip and spirit runs, 2m for one to use for spirit runs only. – If you are like me and have never done this type of work before – buy a couple of meters extra to make a sample and get some confidence.

My first effort was a condenser using a half inch “Cold Finger” down the centre with a single coil that was formed around a piece of 20mm copper pipe.








To make the coil I packed the coils tube with salt – do this carefully - the only failure I had was when, a loosely packed piece of tube creased when I tried to bend it. Straighten the tube fill it with salt, shake it tap it and shake it some more. To fill a 4m piece of tube I did it from the upstairs window and spent 20minutes tapping every inch with the back of a spoon. When the salt does not settle anymore, hammer the ends flat to seal the tube.

Copper “work hardens”, the more you bend it the harder it gets. After you have bent it two or three times (staightening the tube off the roll counts as bending it at least once) it becomes just about impossible to bend again, unless you “anneal” it.

As soon as you feel the tube stiffening up – stop – heat the tube up with a blow torch until it glows a dull red then either let it cool slowly or quench it in cool water. I find it difficult to see the copper glowing red hot in the daylight so I tend to do this operation at night in the dark, and then it is easy.

In addition to never having formed a coil I had never done much soldering I initially struggled with soldering the joint at the bottom of the cold finger, having to take it to pieces and re-solder the joint three times before I got it right. I then had a look at the problem and tried to find a way to eliminate the need for a joint altogether.

If I had to make another cold finger I would make one like this.







An 8mm coil with a 15mm cold finger over an 8mm centre tube and no joint between the two elements, this a short coil made for a friend. I used compression fitting because that is what he wanted soldered fittings would be nicer.

The coil and cold finger can be hooked up either in parallel or series.


Fitting my coil / cold finger in a 2” column left a gap of about 8mm that I originally intended filling with pan scrubbers but, as I said earlier, I now like making coils and it seemed that squeezing another coil in was a good excuse to make another one and the end result should making stripping runs a lot faster.








Enough about my coils – only to say they are easier than you think – Buy 2.0m of tube give it a go!

[YHB]

ignore me bob... i was having a bad day lol.

welcome to the forum.

al.

You are duely ignored.

[Capt-Cudellez]

Lovely work Brian. That coil inside a coil with a cold finger has loads of surface area and knock down power, and you will require very little cooling water to run it.

You may actually have a hard time running it slow enough to avoid "over cooling" the vapour. When i run my stainless VM, I can feel how high up the vapour is getting up the top of the column (this doesn't work on a copper column as it all gets hot) - you'll want the cooling water to be coming off really hot - effectively you have cooled the vapour just enough to turn it to liquid, but it can be easily vapourised again without going too far back down the column.

That's how I see it in my head - might not be factually correct - if I run my cooling too hard, I cannot pull 95%+ without reducing the output from the valve.

CC

[YHB]

Thanks for the heads up. Your explanation clears up a couple of queries that I had.

I intend to plumb the coils in parallel with seperate valved feeds to each coil.

I am anticpating that for column mode I will only need to have the valve to the center coil open, Whereas when I use it in stripping mode with, additional heat input, I may need to open the valve to the outer coil.

Keep the comments coming!

[Capt-Cudellez]

Sounds like a plan Brian, my gut feel is running the outer coil on a run and letting that solid coldfinger\coil deflect vapour out to the outside, rather that the other way round would work better - difficult for me to say when i cant see it built up - if you end up trying it both ways let us know how it works out.

For stripping on one of these, do you just crank it and open the take off valve fully so the lower plate doesn't overflow and send reflux back down the column?

[i dont drink]

for bending copper tube.... iv seen it done with frozen soapy water!.

you fill the tube with it and freeze it and then it can be bent quite easily....

then all you do is defrost it and your done.

al.

[YHB]

Maybe you are right, but with having the balancing valves all I have to do is close one, open the other and see which works best. Thinking about it it would not take much plumbing to put a bypass in, to allow them to run in series, that would cover all eventualities.

My needle valve is on the small size and I am of the opinion that it will be the limiting factor with regard to how much product you can pull off during stripping - so I will remove the valve along with the packed portion of the column and have an unrestricted take off, this would, as you suggest, stop the condensate from going round the loop one more time with no benefit.

I am thinking that I will be having a 3kW element for start up and stripping Approx 1.2kw for spirit runs.

[YHB]

[quote="i dont drink"]for bending copper tube.... iv seen it done with frozen soapy water!.

you fill the tube with it and freeze it and then it can be bent quite easily....

then all you do is defrost it and your done.

al.[/quote]



A couple of questions

1) How do you get 3 meters of pipe in the freezer ?

2) what do you do when you want to anneal it ?

3) how long will it stay frozen - it takes a ccouple of hours to make a coil ??

4) why does it need to be soapy water ?

[Jimmy]

This is all really interesting, good work Brian! It's certainly good to see some UK based info, as you say a lot of stuff is US centric.

[YHB]

just a thought on pipe size.... won't car brake pipe be any good as its pretty easy to bend into shape?

i used some before to make a heat exchanger for a car that i had that run on veg oil,
and i was able to bend it around a 15mm coper tube with ease.

plus its only about a tenner for 25 foot or so.

al.

Al,

It's good to see you thinking.

I used 3.0 meters of 8mm tube by my calculations this has a surface area of 25.163 sq mm/mm. The brake tubing which is 3/16" tubing has a surface area of 12.96 sq mm /mm, So to get the equivalent heat transfer ( surface area ) you need (25.163/12.96) = 1.94 times more tube or in this case 3 /.305 x 1.94 = 19 feet

Just checked on the internet a 25 foot roll now costs 12.75 plus vat (£15.30 Inc Vat)

So 19 of brake pipe costs 15.30/25 x 19 = £11.63
3m of 8mm tubing costs 3 x £3.0 = £9.0

Other considerations

There are cheaper alloy brake pipes but they are not pure copper.

It takes a lot more effort to push water through 19-0 of 3/16 pipe than 3.0m of 8mm tube.

You now have to work 19'-0"" of coiling instead of 3.0m

You now have to find a freezer big enough to get 19'-0"" of pipe in.

Talking about freezers - I Googled "freezing water in copper pipes" and all I got were lots of pictures of copper pipes that had split when they thawed out, why did the one you saw not do the same?

[Jimmy]

How it's Made is great, I am trying to avoid watching it these days as it sends me into some sort of hypnotic trance.

And remember gents, this is the FRIENDLY home distillation site... not that anyone is being unfriendly but I'm keen to keep it that way!

[YHB]

Slant plates
I have seen many remarks in various forums and threads about the Slant Plates in a Boka being difficult to install. They are not that bad at all.

Firstly make a mitre block out of timber. The mitres should be at 30 degrees both horizontal and vertical. Once you have cut the first angle in the first piece of wood, use this as a template for all the other cuts in the wood, this will ensure that all cuts are parallel – it does not matter if they are not exactly 30 degrees but it looks nicer if they are all the same.

It took me about 30 minutes to knock this one up.





Buy a couple of metres of 2” plastic drain pipe and have a play using the mitre block to cut the slanted slots in that before you start on the expensive stuff.



Another Alternative ( and I think a better one )

After I had bought my piece of 2” copper pipe, I talked to a couple of winemakers, who have a combination of limited workshop resources and a lack of confidence with regard to their metal working capabilities but wanted to make a still (they live in a country where you cannot buy one).

I convinced them that I would be able to come up with a design that they could put together with an electric drill and a spanner and no soldering.

The design revolves round pre-made fittings, we have come to call them “cassettes” that the builder can either make themselves or have them supplied depending on capabilities or resources. I am supplying the cassettes to my winemaking friends.

Slant Plate cassette.

This allows the 2 slant plates of a Bok to be inserted into the column. Then the take off and thermometer points are bolted through the wall of the column into the cassette using standard 8mm compression fittings.

I think that:

1) Building the cassette was easier than slotting the column was going to be,

2) If it leaks what will happen? – condensate will run down the inside of the column for additional refluxing – is this an issue, I don’t anticipate it will be?

3) The cassette can be taken out for modification or be easily moved should the need arise.

4) It looks neater - all the gonky soldering is in the inside.

5) Can be used on any tube, one of the cassettes I am supplying is destined to be inserted into a mirror finished stainless tube. – I think this is brilliant and wish I had thought of it earlier

6) The cassettes fit in my mate’s suitcase for going through customs.

7) If it does not work what is the worse thing that can happen ? – I will have to cut two slots for the traditional plates.