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.
Contents
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.