BOK BUILD

[bgrizzle]

So I am on a voyage to build a bokakob double slant plate still... I have built the double concentric circle coil, and now i am working on the slanted plates... Before I go any further, are these plates too close together??? Meaning, should I have raised the top plate up some??? Thank you.

If I messed up, I have more pipe...

This Bok head is going go on top of 4-5 ft column... there will be a SS gate valve to collect the hearts. Basically the Bok is going to be used to collect the fores and heads... I am basically copying Samohon's Liquid/Vapour Management Still...

Thanks guys! I will post more pics as the project rolls on.

[Braz]

I can't say the plates are "too" close together but they are a lot closer than most. Mine are an inch apart (measured vertically) and it works fine. I'd be a little concerned about creating a choke point since you have rising vapor and falling liquid trying to pass through that point.

[Kentucky shinner]

are you using the template that is here on the forum.. If you do it shows you the exact distance I think it is 5/8" but im not sure.
Check this out if you havent already. It says it is for a 1.5" but it also has a template for 2" http://www.mediafire.com/?61di0xcx3z1" onclick="window.open(this.href);return false;" rel="nofollow
KS

[bgrizzle]

I tried the template, but it printed up the wrong size, so I just measured and cut on my own... I think I'm going to sleep on the goof up and try again in the morning. Its not worth five dollars in pipe to just hope and pray. I just think that with the plates so close, the vapour flow up and liquid flow down will not be as good as it should be...

[Kentucky shinner]

I think there to close. I would put about 1/2" between them . It looks like your closer to 1/4" You need a 1/4" overlap but you need about 1/2" or so between the plates.
KS

[bgrizzle]

Question: Would it not be better to have the top plate at less of an angle? If the top plate were at 10 degrees, it would make a larger openeing for the vapour to rise. The liquid would still hit the top plate and trickle down to the bottom plate, but I think the column would breathe/flow better...

Anybody have any thoughts on this???

[Samohon]

Hi grizzle...

KS is right the plates are too close together...
I have them 1" (25mm) apart on the center line...

Heres a piccie going with dimentions from your 2" pipe...

If youve got some 2" copper, then I would re-cut the plate slots.
Use 30° for the angle and you should have the take-off and thermo ports seated just nice...

The template will at least give you the correct angle, even if its not to scale...

Bok-Temp.jpg (12.42 KiB) Viewed 3099 times

Were here to help buddy, re-cutting is the only way out here, the plates are too close together...

Good Luck man, an keep going...

[bgrizzle]

$5.00 mistake... God knows I've made more costly mistakes in my life!!

If anything was hurt here it was my morale... after all the reading I've done, I should have known that they looked to close. I had a hell of time cutting the slots... thats what kills me! I dont have a band saw. All i have is a jig saw, hack saw, table saw, miter saw and some air tools. If i had a band saw, I would have already cut a new pipe!

Perhaps a trip to the hardware store... I'm kind of cheap and I like the challenge of using what I've got. If anybody has any suggestions on cutting those damn grooves, I would appreciate it... I guess I could use my miter saw, but the blade is so thick I think the groove will be too thick...

[hoody]

The template diagram say's to place them 1/4" apart but I gave mine 3/4".
1/4" just did'nt look "right" to me? Yet to run mine but we will soon see!

Hoody

[bgrizzle]

Thanks Hoody! It seems like the consesus is 5/8"-3/4" distance between plates... I swear, i think that template shoud be updated!! I would have been better off going with my gut!

[hoody]

That's how I came up with my 3/4" spacing. I just read through everyone else's build's and came up with a bit of a "average".

[Samohon]

The template diagram say's to place them 1/4" apart but I gave mine 3/4".
1/4" just did'nt look "right" to me? Yet to run mine but we will soon see!

Hoody

+1 Hoody, I done the same man, just thought that ¼" was a bit small for all the work going on in there, especially when strippin a wash...
Let us know how you get on with your first run Hoody...

¾" to 1" will be fine grizzle... Go for it man...

[Samohon]

Perhaps a trip to the hardware store... I'm kind of cheap and I like the challenge of using what I've got. If anybody has any suggestions on cutting those damn grooves, I would appreciate it... I guess I could use my miter saw, but the blade is so thick I think the groove will be too thick...

If it's a compound mitre saw grizzle, (0º through 90º), you could try and get a thin soft metal blade.
As you know, I used a hacksaw and a home made mitre box with slots cut @ 30°. Worked OK man...

[bgrizzle]

Thanks guys... I'll be in the garage tomorrow... I've already built my liebig condenser and double coil condenser. The SS gate valve came in today. I bought a 15.5 gallon keg from a local brew shop for 30 bucks. From here its just building this Bok and some simple soldering to put together all the puzzle peices I've got a 55 gallon drum with a 500gph pump to recirculate the water... I'll take pictures and post once everything is all done... I think I'm going to have a pretty nice setup! Not sure how much time I'll have tomorrow... the wife has a photographer taking pictures of our twin babies tomorrow... I love my hobby, but the babies are number one! well... number one and two!

[NcHooch]

Hey Grizz,
I dont think I ever saw the template when I made mine so I was wingin it....and they're right about 7/8" apart.

When I cut my slots, I used a hacksaw in a mitering jig .....but the slots were too thin so I had to go back with a sawzall...
that was a lil sketchy, cuz we all know how the sawzall likes to grab occaisionally. turned out OK though.

my plates are actually in seperate parts (tubes) of the still, I don't think it makes much difference...just the plans I followed

I'm not to far from you, about an hour east.

NChooch

[Samohon]

The hard work is done on your build, there really is nothing to soldering the plates in place...
Just do them like I said, one at a time... Doing the take-off and thermo ports as you do their respective plates...

Good luck with the photo-shoot tomorrow... Kids really are a gift...

[still crazy]

Ya a made a wood box jig to cut the slots.
Those are tight the flow space between the plates will be choked.
3/4" should be fine

[rad14701]

Having the plates too close together will not only cause choking/flooding but will also increase the vapor speed through the plates - which is why there ends up being a choking/flooding problem... The greater the gap between the plates, within reason, the less vapor speed increase you will have to worry about... The same problem arises when building a two reducer LM column that has too small of a vapor/reflux throat between the lower packed column and the reflux head...

[still crazy]

For 10 HD points name the theorem that explains this ....

[Pooyan]

For sawing the slots in i used a iron saw, the dremel was used for cutting the plates.
The copper plate was 0,7mm thick, made the bending of the tip of the lower plate also an easy job, found the piece of copper at the scrap yard.
Tape the template with wide tape a couple of rounds firmly on the copper pipe, so that the cutline will be the only thing disappearing while sawing.....

if you haven't cut the plates yet, use a piece of that pipe with the "old" slots, a little flathammering and ready you are...

Good luck with your build bgrizzle, you will be amazed how smooth she will be running when ready!!!!

Pooyan

[Pooyan]

One more thing, (just in case you haven't read it here somewhere already), don't forget to solder the bottom plate in first, makes the bending of the tip a lot easier

[Samohon]

One more thing, (just in case you haven't read it here somewhere already), don't forget to solder the bottom plate in first, makes the bending of the tip a lot easier

+1,Yeah, forgot to mention that grizzle, bottom plate/take-off tube soldered first, bend center tab down, then solder top plate and thermo port...
The hardest part of the build for me was the rolling of the coil (steep learning curve), Reckon you'll do OK man...

[Kentucky shinner]

The template diagram say's to place them 1/4" apart but I gave mine 3/4".
1/4" just did'nt look "right" to me? Yet to run mine but we will soon see!

Hoody

This is just for anyone else who may be reading this and doing a bok build. The template actaully says 1/4" overlap. It is talking about the the distance of the top plate that extends over the bottom plate, not the actual distance between the two but the overlap. The distance should be 1/4".
Just wanted to clarify that.


Your gonna love your Bok Bgrizzle. You did good by asking . your bok should perform as designed now... Way to go.
KS

[Samohon]

The template diagram say's to place them 1/4" apart but I gave mine 3/4".
1/4" just did'nt look "right" to me? Yet to run mine but we will soon see!

Hoody

This is just for anyone else who may be reading this and doing a bok build. The template actaully says 1/4" overlap. It is talking about the the distance of the top plate that extends over the bottom plate, not the actual distance between the two but the overlap. The distance should be 1/4".
Just wanted to clarify that.

Your gonna love your Bok Bgrizzle. You did good by asking . your bok should perform as designed now... Way to go.
KS

+1 KS, the distance is important to prevent chocking, as Rad has pointed out... I increased it a little as I felt, with the amount of heat I would be throwing at the boiler, it was just a little on the small side. Most of the posts on HD reflected this at the time I built mine, so I just followed along...

I think Alex Bokakob was giving a minimal clearance based on vapour flow afforded to a certain KW/BTU of heat input to the boiler...
I'll try later to find his theory behind the plate distance in relation to heat...

Now get those damn plates soldered in grizzle , and take some piccies for us...

[Samohon]

For 10 HD points name the theorem that explains this ....

Not sure SC, but I think its the Venturi Effect.
Restriction (Choked Flow) on liquids/vapours....
I'd have to consult my notes....

Maybe you'll send us a Bok head in the post if we get 50pts....

[still crazy]

Venturi effect is another thing that this theorem explains
Hint : It is also the theorem that explains how a plane flies.

[Braz]

Bernouli (or however it is spelled)?

[Samohon]

Yeah, like braz says, Bernoulli, or whatever spelling.... Close though....

[Austin Nichols]

I put my plates about half inch apart when I built mine, I'm pretty sure the rumbling noise my bok made was flooding of the column after reading comments here.

I am thinking I might need to rebuild the condenser housing now.

Cheers.

[bgrizzle]

ROUND TWO:
I tried again today and here are the results:

BOK 2nd attempt

BOK view from the bottom

There is some solder on the inside of the pipe, is that ok? I think the plates are about 3/4" apart...

Here is a pic of the liebig condenser I built last week. Its kinda big, but I had some 1" and 3/4" pipe in a recycle pile at my warehouse!

lieBIG condenser

And here is the SS gate valve I'm going to use:

SS gate valve

SS gate valve thread view