Beginner Information and Suggestions for the Boka Reflux

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Beginner Information and Suggestions for the Boka Reflux

Postby Phil » Mon Feb 11, 2013 6:19 pm

This is the guide that I wanted when searching for all the Boka build info, some of it is specific to those without access to a keg.

Beginner information and suggestions for the Boka Reflux Still

The 2” Boka Reflux Still is a great first build. Capable of producing 95% neutral spirits and can be tuned to produce quality flavored spirits between 75% and 90%. All the materials for this build are locally available at reasonable prices, the 2” copper and stainless steel pot are the main investments and both are adaptable and reusable for subsequent builds.

This guide is created to provide information and suggestions for specific aspects of the Boka Reflux Still build and is written for the beginner. I will focus on areas of the build that generate the most FAQ’s and focus on one particular build rather than trying to cover the many alternatives. This guide doesn’t provide specific diagrams, rather allows the builder to use the pictures and information to assist in the decision making process of their own build.


1. Build overview
2. Boiler and column connection
3. Sealing the pot lid
4. Slant plates
5. Condenser
6. Take off pipe and valve
7. Product Condenser
8. Heating
9. Column Packing
10. Operation
11. Other tips

Build overview

The build referenced and pictured in this guide is my 2” Boka Reflux Sill on a 32L stainless steel boiler. Double wound coil with Liebig outlet condenser.


Boiler and column connection

The most common boiler found in the distillation hobby is the standard 50L keg. Much information can be found regarding kegs and column connections. If using a keg see the easy flange thread here: viewtopic.php?f=41&t=76 . Using an easy flange allows the column to be connected to the keg using a triclamp.

Unfortunately kegs are not readily available, and when they are you often pay a premium price. The best available alternative is a large stainless steel cooking pot with a stainless steel lid. These can be found on e-bay in various sizes starting from $70. A good size for your first still is 32L. 30L of liquid has a manageable weight that won’t require special plumbing and 30L plastic fermentation vessels are readily available. If fermenting a 30L wash this also allows some ‘head’ room in your boiler. You may also wish to consider that wider pots are more stable and contribute less to the overall height of your still.

Many options exist for connecting a copper column to a SS lid however most require sourcing specific fittings or access to expensive welding equipment. The method described here is a relatively simple connection that can be accomplished with common DIY tools.

Cut a 2” hole centered on your lid. The hole does not have to be perfectly smooth but the closer to the OD of your 2” pipe the better. However you decide to cut stainless steel it is important not to let it get too hot, if too hot the steel will harden and become almost impossible to cut. Cool as you are cutting with water in a spray bottle or cutting fluid, WD-40 etc… A Dremel with at least 3 spare cutting disks will be required depending on the thickness of the SS. Some guides suggest drilling multiple holes and filing down the final edge. A high quality hole saw could be used but would require a large drill press due to the size of the lid.

To connect the column we will use a direct fitting method that will result in a join as per the below image.


To do this you will need to make a 16cm long template with markings each 32mm.


At each of the 5 markings cut 6cm deep into the end of your 2” copper pipe. Carefully hammer the 5 flaps until they are flat. Centre a hole in each flap to fit either 6M or 7M bolts. Each flap will be slightly different so number them and trace them onto paper. Use this new template to mark the holes on the lid. Don’t forget to cool the SS when drilling out the holes on the lid.

Insert your bolts with washers on both sides of the lid and before the nut on the copper. Tighten alternative nuts slowly as you would nuts on car wheels, finally tighten very firmly. Hammer the copper into the bottom of the lid so it looks something like the picture below. The aim is to seal the copper to the lid as much as possible to making soldering easier. Tighten the bolts again prior to soldering.



Clean the pipe and the lid and apply flux. Using soft lead free solder you want to work at low heat. The idea is to create a bead of solder, using too large a flame or a MAPP torch will provide too much heat and the solder will run into the grooves. First heat the lid then the pipe, apply solder to the pipe about 10mm above the join keeping the flame 20mm above the join. Work your way around and when you have a large bead return to heat the stainless again until you see the solder melt around the edges and stick to the lid.

The bolts are for strength and the solder is just a seal, if you have a leak just clean it up, flux and solder again.

Down the track you could also cut the 2” pipe just above the lid and make an easy flange. The system would then be modular and easier to store. You could build a pot still or even a flute column onto the same boiler.
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Re: Beginner Information and Suggestions for the Boka Reflux

Postby Phil » Mon Feb 11, 2013 6:26 pm

Sealing the pot lid

Sealing often causes discussion due to the safety issues of material compatibility with hot ethanol vapor. It is mostly agreed that copper, stainless steel and PTFE are safe to use and there is often debate over brass and some specific silicones. It is also mostly agreed that the easiest seal is achieved with flour and water. Mix a doughy paste of flour and water and spread it around the seal before clamping down the lid.

A reusable alternative to flour is an “Everlasting Gasket” this is simply a ring of cardboard cut to the shape of your boiler lid wrapped half a dozen times with PTFE Teflon plumbers tape. Examples can be found on Aussie Distiller, here is one on my 32L boiler after 10 runs.


Slant plates

The theory behind the slant plates on a Boka Reflux Sill is simple: all liquid condensed above the slant plates is collected. The operator then decides how much liquid to collect and how much to reflux to the column by adjusting an output valve. The output valve is mounted just above the bottom slant plate.

A template to cut your 2 slant plates and grooves into a 2” column is available via the Wiki (link below).

Build a wooden saw box and create guide cuts at 30 degrees as pictured below. When cutting the pipe start your cut perpendicular to the pipe and after a couple of mm cut at 30 degrees with the wooden guide.


If you have left over copper pipe you can cut and flatten to make the 2 plates. 2” pipe is 2mm thick where ¾” pipe is 1.5mm thick. As you will be cutting the slants with a hacksaw blade the thinner pipe will be a better fit. If your plates are too thick you can enlarge the cut with a Dremel and cutting disk.

There is no reason to cut the plates perfectly flush with the column. Plates that protrude a couple of mm will be easier to solder as there will be more available surface area. Columns should be insulated so it doesn’t matter it doesn’t look perfect.

There are many older guides that suggest soldering the top slant plate to the bottom of your condenser, this is not ideal as it leaves a gap between the plate and the column where liquid will not be collected. Cut groves for both plates around 2 cm apart and solder both in place. The bottom plate should have a tongue that can be bent down after the plate is soldered. This returns liquid to the centre of the column rather than letting it run down the column walls.


Install plates in the following order:

1. Cut slant grooves
2. Drill product outlet and thermometer holes
3. Anneal bottom plate
4. Solder bottom plate
5. Bend tongue on bottom plate
6. Solder top plate

Mount your thermometer below the bottom plate. I drilled a hole only large enough for the thermometer tip and soldered on a short length of ¾” directly to the column. This way you don’t have to put a big hole in the side of your column.

Pay attention to the orientation of your thermometer display. Everything else is reversible so this may decide the layout of your still.


Detailed condenser guides can be found with a search of aussidistiller and the internet. For this build I recommend a double wound condenser, 200mm will give you plenty of cooling power to knock down all vapors. Copper or stainless scrubbers can be wedged into condensers to improve their efficiency if required. Always make sure the column is open to the atmosphere above the condenser. You don’t need a cap but if you have one drill a hole in it at least 10mm in diameter and ensure it is never blocked.

Brass hose fittings are available at hardware stores, drill and solder these to the input and output of your condenser allowing the cooling to be done with 2 garden hoses. The brass is very easy to solder to copper. It is also worth investing the few dollars into new fittings for your garden hose.

Take off pipe and valve

Most guides suggest using a 1/4” take off pipe however others suggest you could run your Boka wide open without reflux if only you didn’t use that ¼” take off pipe! I suggest using a ½” take off pipe and a ½” valve to control the amount of output and reflux. Open and close the valve you are going to purchase, do you have good control between closed and just cracking it open?

Product Condenser

I strongly suggest including a Liebig condenser to cool the output liquid before collection in glass jars. The Liebig is simply a larger pipe with cool flowing water surrounding the product output pipe. A 50cm Liebig is more than enough for this build and it can be run vertically down the side of the main column with a couple of supports for strength. This link has some good diagrams showing how this type of condenser works. ... ild#p23570 . A Liebig provides a safer product output that can also be immediately measured with an alcohol meter in a parrot.

Coolant should enter the bottom of the product condenser Liebig then flow to the condensing coil before returning to your coolant tank.


I suggest a cheap gas burner for this setup. If you pay attention to your still and run it outside then gas is a safe option. A 2 ring burner outputting 12MJ per hour is sufficient to heat and run a 32L pot.


Column Packing

There are many options and suggestions for column packing. If making neutral spirits the aim is to maximize the surface area in your column for this I suggest structured copper mesh. This mesh can be found online at homebrew/distiller sites, it is also sold as a pest barrier. If purchasing as a pest barrier be sure the product is 100% copper untreated. An easy alternative is large stainless steel scrubbers from a hardware store. Raschig rings, marbles etc… are not ideal due to weight and cost. Most utilize copper over stainless as it is said to remove sulfides from the product.

Clean your copper mesh occasionally in a solution of 1 part vinegar to 10 parts water.



Operation of a Boka Reflux Still is an extremely simple yet refinable task. The still is capable of striping runs, high abv neutral runs and flavored spirit runs. Assuming you have a pump and water tank there is no need to adjust the rate of cooling, run coolant wide open. If you need to conserve water then coolant only needs to run fast enough to knock down all vapor. Prior to a run you may wish to adjust the amount of packaging in your column. You have control over a run through controlling the amount of reflux and the amount of heat applied to the boiler. You will need an alcohol meter to test the ABV of your product and ideally you will have a parrot. Following is a brief explanation of the three runs.

Striping run – Quick run to collect ethanol from your wash, resulting product to be added to the product of subsequent striping runs in preparation for a final spirit run. Removing column packaging will speed things up. Leave the burner on high heat and take off valve wide open. Discard fore-shots and collect until column temp is around 95 degrees Celsius or output is below 40% ABV.

Flavored spirit run – Pour 3 or 4 of your striping runs into the boiler and dilute with water down to 30-40% ABV. Close the output valve and heat the boiler. Once the column reaches 78 degrees turn down the heat and allow the column to equalize at full reflux for around 30 minutes. From here you will need to find a balance of heat and reflux to reach your desired ABV output. I run at low heat, wide open usually with half packaging installed, heads are usually done by the time I get down to 80% and I usually keep spirits down to 65% before turning the heat back up and running the remainder as tails. You should still taste after airing spirits however I find this is a reasonably fool proof way to spirit run.

Neutral run – This is a slow spirit run aiming to achieve a clean 95% spirit. Fully pack the column, turn down the heat once up to temperature, run at full reflux for around 45 minutes. Slowly open your take off valve until you’re collecting at a rate of around 2 drips per second. Discard fore-shots and collect heads before collecting hearts. This will make for a long day but the slow take off rate will ensure a clean tasting spirit. You can output faster however I find unwanted taste sneaks into the final product. During the run you should be outputting between 95 and 94% and once it drops to 93% it is time to turn up the heat and collect the small amount that will be left. Collect in smaller jars towards the end of the 94% output to check for unwanted flavors.

Other tips

Insulate your column. Copper transfers heat extremely well, insulating helps to maintain an even heat distribution.

Try everything!!! For example – Try distilling your tomato paste wash 3 times for a truly perfect neutral product.

Don’t forget to run a vinegar then ethanol clean / test.

Further information can be found via aussie distiller search and at ... w_To_Build .
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Re: Beginner Information and Suggestions for the Boka Reflux

Postby MacStill » Mon Feb 11, 2013 6:33 pm

Great work Phil :handgestures-thumbupleft:

Some real quality postings going on lately, thanks to everyone involved :-B
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Re: Beginner Information and Suggestions for the Boka Reflux

Postby Kimbo » Mon Feb 11, 2013 11:35 pm

Bloody good work mate :handgestures-thumbupleft:
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Re: Beginner Information and Suggestions for the Boka Reflux

Postby Phil » Tue Feb 12, 2013 8:08 am

Thanks guys, some simple stuff but when starting it's all a foreign language. I'm happy I built a Boka first and hopefully this helps some of the new guys do the same.
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