StillSmart

Re: Brian’s Bokakob

2012-10-11T11:52:48+00:00

Jim,

Welcome to the forum.

I believe what makes the valve work so well is the tall configuration that you query. If the valve was short and stubby the needle would be very stiff. If this was the case then when the valve was closed the needle would just travel in the direction it was pointing making alignment with the outlet hole very critical.

With the tall valve the needle is flexible, in this instance when the valve is closed the needle simply bends and follows the taper in the brass cap and self-locates in the outlet hole - it just works.

To form the point on the needle I simply put the spoke in an electric drill - poked the tip of a spoke through a hole in a piece of wood to give it some support, turned on the drill and ran a file over the end of the spoke - 10 minutes finished.

I put the valve away from the column to allow for insulating the column.

Having an inlet / outlet limits the amount of pooling, only one outlet will increase it.

One other point to consider is that if you have only an outlet then the pool of distillate will form a vapour trap. With the inlet / outlet configuration there is a theoretical route for vapour to follow the needle up and out of the top of the valve stem. To prevent this I introduced a seal at the top of the valve stem. I did this by rolling some silicone sheet into a tight cylinder and pushing it into the top of the valve stem, then pieced this packing with the point of the valve needle which caused the packing to be compressed even more tightly between the needle and the tube forming the seal.

Glad you liked the design, out of all the bits I made this is my favorite it just works.

Since my last post, I have added a 600mm packed pice to the column. The Bok just sits there and gives a steady 95.5%. The valve helps as it is very controllable, on a spirit run I can set the flow rate to 1.25 litres per hour to get the 95.5%, but if I am running a 10% wash then I need to turn the rate down to 0.9 litres per hour to get the same strength.

Hope this helps, I am glad that you are stealing my design that is why I published it, I hope yours works out as good as mine, if you can think of any ways to imrove it please let me know. The only thing I ask is that you publish some pictures of the finished item.

If you have any more queries then ask away.

Statistics: Posted by YHB — Thu Oct 11, 2012 11:52 am

Re: Brian’s Bokakob

2012-10-11T08:36:06+00:00

Regarding your needle valves.

I am in a similar position, where I do not want to pay a fortune on needle valves, and am unafraid of trying to build my own. A google search led me here, thanks for sharing your experiences building one!

It seems to me that in order to minimise pooling of distillate at your takeoff valve, you could use your second valve design, but mount it higher, using the opening you are using as a drain as the main inlet, and omit your current inlet. Also, is there any reason you build them so tall? How do you shape the point on the bike spoke? Is there any reason you have the valve so far from the column?

I think your valve is great, and plan on stealing the overall idea. Thanks!

Statistics: Posted by jim — Thu Oct 11, 2012 8:36 am

Re: Brian’s Bokakob

2012-09-02T16:22:56+00:00

I am still playing around to see what the various options do.

I have just done a stripping run on a 21 litre 14% wash (Vodka Star) to make a neutral. I removed the reflux valve but left the small amount of packing in the column.

Switched on and it took 25 minutes for the first product to come through.

In another hour I had 3.5 litres and was still pulling 85%ABV, it took another 30 minutes to get the last 0.7 litres, by this time the temperature was 98 deg C and the distillate was barely dribbling out and it was not worth the electricity to collect more, even though it was still pulling over 60%ABV.

From switch on to close down in under two hours I finished up with 4.2 litres @ 79%. That will do very nicely thank you. Using this method for a flavoured wash might not be a good idea, but for a neutral it seems quite promising.

I will do two more of these in the next couple of weeks and then set the full length column up for the spirit run.

Life just gets better.

Statistics: Posted by YHB — Sun Sep 02, 2012 4:22 pm

Re: Brian’s Bokakob

2012-08-21T20:02:55+00:00

Dead chuffed for you mate knew it looked an impressive bit of kit well done

Statistics: Posted by Admiral Toad — Tue Aug 21, 2012 8:02 pm

Re: Brian’s Bokakob

2012-08-21T19:56:57+00:00

Great work Brian. Congratulations. My theory is that the attention and care you lavished on you design and build has imprinted the still with a sense of purpose... It knows what it is supposed to do and is trying hard to do it's best

Statistics: Posted by ant — Tue Aug 21, 2012 7:56 pm

Re: Brian’s Bokakob

2012-08-21T18:29:56+00:00

I'm not sure I have any answers for you Brian, I'm also a bit surprised you were pulling such high ABV, was the reading at 20oC? Great result all the same.
For rum, I wouldn't bother putting an extension on, but for neutral if you have the head room I'd give it a go. Only you can decide if you think its worth the hassle.

With my VM I was able to pull 95.6% when packed with scrubbies, If I ran a bit too fast, I could still pull that ABV but the quality suffered, the spirit tasted hot and wasn't as smooth. With SPP I still pull the same ABV, but the spirit is very smooth and very neutral, I guess this is the equivalent of running with some extra height (more theoretical plates), it was as good as the double distilled runs I'd done.
What I'm saying is not all 95.6% is equal, for flavoured spirit the shorty may be better, if your after ultra pure neutral it might be acceptable, or it might not, only one way to find out I guess.

Statistics: Posted by Capt-Cudellez — Tue Aug 21, 2012 6:29 pm

Re: Brian’s Bokakob

2012-08-21T17:42:26+00:00

IT WORKS !!!!

I have done several stripping runs and a couple of spirit runs in Pot Still Mode with the reflux valve removed. I am very pleased with the results, but there again I would be, wouldn’t I.

I had an impending spirit run of 20litres of 35% Rum and was debating whether to run it as a pot Still or try the reflux out.

To test the valve and clean it, I put 12 small scrubbies in the column without adding the central column extension. This gave me less than 12” of packing. I loaded the boiler with 15% junkahol and turned it on.

I let it boil for half an hour to clean the valve and then turned it on, without any adjustments it pumped out 95.5 to 96 %ABV - measured after cooling overnight, as it was coming off the still hot the distillate was measuring 101% which looked impressive.

A couple of days later I ran the Rum through it without changing the configuration. 1 hour equalisation and three hours for the heads. Opened it up to 1.2kw and set the valve to give me 1.4 litres an hour.

I ended up with 4.1 litres of 95.5%.

This result is far better than my expectations and I am delighted with the results. The question is, why is the ABV so high?

All the reading I have done tells me that I should have 4 times as much packing and the column needs to be 2.5 to 3 feet higher.

Is the height only about strength or does the additional height do more?

Is it worth adding the column extension for another 1/2 %?

Does that last 1/2 % make that much difference?

For a first run I am delighted, I still have a lot to learn,.

Many thanks to all for the support and encouragement and advice.

By the way, the rum is Awesome.

Statistics: Posted by YHB — Tue Aug 21, 2012 5:42 pm

Re: Brian’s Bokakob

2012-07-13T12:22:40+00:00

I finally finished mine after several months of aggregating parts. It is a basic boka with triclamp ferrules and a compression fitting for a thermocouple. Otherwise, it is nowhere near as elaborate as Brian's.

A couple of things that I learned from my build is 1) never use a step drill bit on a angle to avoid creating a larger, and also elliptical hole and 2) focus the heat more on the ferrule when brazing it onto a Still Spirits Super Reflux boiler lid to avoid warping the relatively thin lid.

Thanks to all for the great info and showing it can be done.

Statistics: Posted by Keystone — Fri Jul 13, 2012 12:22 pm

Re: Brian’s Bokakob

2012-07-08T15:30:29+00:00

Bloody hell. It doesn't look much like any of the images/pic's of a Bokabob I've seen before, but damn! it looks like a fine piece of workmanship.

I've "skim" read the entire thread, but need to think some more about this building idea. I certainly need to re-read the thread properly, to get the idea's and concepts that've been explained into the old grey matter.

I started collecting bits for a "home build" a couple of years ago, but I'm that decisive, that I still can't make my mind up on how I want to progress.

Some of the info, I follow completely already, but there's a few bits that don't make sense to me at all.

Ah well, I'd be happy to read any reports on how this is working, as it'd brilliant to have a still that will produce the standard max strength spirit in one pass (despite it being my habit to run a batch once, then let it down with RO water and re-run it).

Top banana to all who have either posted/included info in this thread..... it's totally brilliant IMO.

Statistics: Posted by Phantom — Sun Jul 08, 2012 3:30 pm

Re: Brian’s Bokakob

2012-04-01T18:51:26+00:00

That's a work of art Brian, highly functional art.

Congratulations, I'm seriously impressed. When's the commissioning party? I'll even bring a bottle or two!

AM

Statistics: Posted by Almanac — Sun Apr 01, 2012 6:51 pm

Re: Brian’s Bokakob

2012-04-01T16:06:29+00:00

Nicely done brian - can't wait to see the whole thing put together.

CC

Statistics: Posted by Capt-Cudellez — Sun Apr 01, 2012 4:06 pm

Re: Brian’s Bokakob

2012-04-01T15:04:03+00:00

It's nearly there.

Just the final connections to the water suplly and drains when it is in it's final stilling place and that will be that.

Ok now to go and attack the boiler

Toodlepip

Brian

Statistics: Posted by YHB — Sun Apr 01, 2012 3:04 pm

Re: Brian’s Bokakob

2012-03-27T19:19:47+00:00

Nice one Brian. I was afraid to ask why there are four pipes - took me a while to figure it out Shit! I'm getting slow.

I didn't enclosed mine the way yours is - mine just drops into the top of the column. Nice idea, looks really neat and clean.

AM

Statistics: Posted by Almanac — Tue Mar 27, 2012 7:19 pm

Re: Brian’s Bokakob

2012-03-26T17:08:12+00:00

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

Statistics: Posted by YHB — Mon Mar 26, 2012 5:08 pm

Re: Brian’s Bokakob

2012-03-26T17:01:10+00:00

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

Statistics: Posted by Capt-Cudellez — Mon Mar 26, 2012 5:01 pm