Bokakob 2" mini-still column

[Austin Nichols]

Run water in the top and out the bottom.

Why?

[maritime]

Run water in the top and out the bottom.

you always run cooling water from bottom to top. this gives you a static line 100% of the time.

steam you run from top to bottom, so the condensate goes to the bottom and the trap removes it.

[crazyk78]

Sorry correction there, maritime is correct. Heat rises so you want to push the hot stuff out.

As far as getting rid of the tee's just imagine this

If water was taking the high velocity path coming down from your coil, it would want to pass straight from the top leibig tee to the bottom leigig tee and out the tube. This is because, as others have stated water will take the path of least resistance and going in and around the leibig causes turbulence and resistance hence increasing the back pressure.

if you remove the tee then the water has no choice but to go through the leibig.

hope that makes sense.

[Usge]

Thanks to Pikluk for this great thread on his boka build.

In his original post here...he has some pics of his plates he cut out prior to soldering them. Just looking at them...does it look like the lower plate is trimmed back to expose the tab, rather than just notch cutting the tab in the middle? From reading the provided template, they seem to be saying to just notch out the front tab and bend it down in the middle. It looks like the bottom plate he made is actually shorter than the top plate....is this correct?

I'm getting ready to do a 2" build and just wanted to clarify that. Also, I know consensus seems to be .75% down/gap between bottom of plates, with a 1/4" overlap horizontally. How much room above top plate (below condensor) is necessary/optimal? That's a little unclear to me given some attach bottom plate to condensor.

I've collected all the parts/pieces...but the only thing I've finished so far is my reflux condensor. Couldn't do the double coil...just couldn't get the first one to wrap over. So, I used a .75" stubbout and made a cold finger. Took a few tries to get it soldered up without leaking. I water tested it and it flows just over 2 liters a min off my sink. I used the recommended 1.25" mandrel to wind the outer coil...and to the tell the truth...could have probably use slightly larger (it still fits rather loose inside 2" pipe)— probably gonna use some mesh. It ain't purdy, but it works. It's about 8" long to tip end of cold finger. Gonna try and do the cuts on the pipe this weekend.

[rad14701]

Nice looking coil over coldfinger condenser, Usge... It should knock down most anything you throw at it in a 2" dual slant plate...

There is no minimum distance between the upper plate and the bottom of the reflux condenser, but you probably want at least 1/2" - 1" of clearance, minimum, with about 1 column diameter being towards the upper end... Much beyond that and you're just allowing the vapor to convert back from being turbulent to a straight upward route of travel... My condenser actually sits on the slant plate in my LM rig, with the top couple winds extending above the column head, and I've never had a problem...

The amount of overlap isn't overly critical, you just need to have a complete overlap... And as long as the centering tab actually centers the reflux the layout of the bottom plate isn't overly critical... Remember, the further past column center each plate extends, the greater the increase in vapor speed through the reduced area in the dual plate section...

[Usge]

Thanks Rad. Measuring the condenser length a little awkward...since it has a cold finger. The actual flat coil bottom sits a good 1-1.5" higher up than the very bottom of the finger. So, I'll probably just take to end of finger and add 1/2" then.

Got a friend who has compound miter power saw who I'm hoping will do the cuts for me this weekend. So, I'm just trying to figure out best way to use the templates to tape it up/mark it for him. I'll watch for keeping the 1/4" overlap of plates across the middle. Just have to work slow, keep test fitting to make sure things go right. I may end up cutting it myself. Had no luck finding a compound miter hacksaw that would do 30 degrees or so. So, may have to either just eyeball it using my vise and hacksaw, or I could use dremel cutting tool. My feeling is...hacksaw might be more stable side to side/across for an even cut, but harder to correct course along the way....whereas dremel would be easier to follow along the mark, but might waver more along the way. 6 or 1/2 dozen I guess.

[rad14701]

Usge, I'd suggest making a jig for cutting the slots for the plates like still crazy did HERE... Some folks use two hack saw blades to make a wider cut but you may not need to...

I had a buddy try to help me make slots back when I made my small scale LM rig and he butchered them, which is why I ended up going with the dual reducers in place of the butchered section of copper... I went to use the telephone and when I returned he had made a terrible attempt at cutting slots with a pneumatic cut-off wheel... I still have that abused piece of copper kicking around as a reminder to no ask for or casually accept help in building my stills...

[Usge]

To be honest...making that jig looks harder than what was already in front of me . Maybe I can just get him to help me build the jig? That way if he screws it up...it's just the jig...and not my copper.

[rad14701]

To be honest...making that jig looks harder than what was already in front of me . Maybe I can just get him to help me build the jig? That way if he screws it up...it's just the jig...and not my copper.

Yeah, for a one-off it might not be worth the effort to make the jig... I had mine marked out with masking tape and rough measurements, which would have been fine if cut with a hacksaw... I made a slant plate section for a buddy by using a simple jig that was just a piece of wood with a 30 degree cut and both pieces clamped on where I wanted to make the hacksaw cuts... Laid the hacksaw on the wood and cut to a depth line marked on the wood pieces... Sometimes close enough is, well, close enough...

[Usge]

I reckon might be easier, despite the cost, to just pick up one of these? (says it does 30 degrees and up to 6"). 49 bucks from McMaster Carr. 14 bucks for the copper/alumn/soft metal blade. Beats buying more copper.

4201a38p1l.png (15.65 KiB) Viewed 13161 times

[crazyk78]

OMG Usge....I have one of them and never thought of using it...just stuffed around freehand.

That would work fine.

[rad14701]

Is that angled on the wrong plane...??? You need to be able to angle off perpendicular... Like / instead of |...

[Usge]

Rad, I think the saw is attached to a rotating plate on the bottom marked at various degree points with zero being straight. It can do both positive \ and negative/ cuts by rotating it left or right in reference to the material holder/vice. I think it works just like a regular miter box. The harness it sits in is for setting the depth of the cut. Here's the specs from McMaster's site:

Durable and accurate, this miter box saw has a solid one-piece aluminum frame with guide rods that keep the saw parallel to your material. Angles are set at 90°, 45°, 36°, 30°, and 22.5° left and right. Saw includes a 23 5/8" Lg. x 1 3/4" Wd., 14 teeth per inch, carbon steel wood-cutting blade and a material clamp. Table is 15 1/2" x 3". Max. cutting height is 6"; max. cutting width is 4" at 45° and 6 3/4" at 90°. Overall length is 27 5/8".

The 24 teeth per inch blade for cutting metals is an extra 14 bucks. So, with shipping/tax probably cost around 60 bucks.

[rad14701]

I know how they work... The problem is that the saw needs to be angled, top to bottom, not side to side... Trust me, I just looked up several sources for hand-tool versions and none of them, aside from power miter (mitre) saws, angle that way... That "left and right" is on the wrong plane...

[Usge]

Ah, see what you mean. Don't know.

[Azframer]

What Rad is saying is that saw will miter, it will not bevel.?

[crazyk78]

Yes you are right Rad. You can only angle from side to side not top to bottom which is needed.

[Azframer]

I am thinking about building this, any chance I could use a slide compound miter saw for this with a thin kerf blade?

[rad14701]

I am thinking about building this, any chance I could use a slide compound miter saw for this with a thin kerf blade?

Yes, a compound miter saw will allow the "beveled" cut you need... Hopefully you'll be able to find a thin enough blade... Band saws also work well if you have a blade that can handle copper...

Thanks, AzFramer, for posting the word that was eluding me... I was having a mental midget moment and I was trying to find it in the miter saw descriptions... It's been a long week...

[Azframer]

Well Rad it happens to the best of us. I got so many tools just sitting idle that I have 2-3 of, I was thinking of selling some so I can get the parts to make a build. I got 3 Hitachi framing guns and 2 roofing guns same brand. Hell I am 46yrs old and nothing will be happening around here for a while, I'm used to run 4-5 guys out of my tool box. Not sure that will happen again until this economy picks up.

[Usge]

Ya...I get it rad. You are right. Back to the drawing board with that one. They don't make bevel hacksaw miters. I've got a feeling I'm going to be winging this freehand in the end with either the dremel or the hacksaw. If I had capability to bevel cut wood accurately for a guide...I'd just as easily be able to bevel cut the copper in the first place.

Having trouble making sense of the template in another regard. There are 2 strips that show the intersection of the plates and overlap of 1/4". Then there's the quadrant/full cut template. The issue I'm having is they don't seem to agree with each other. The intersection one shows accurate dimensions of the plate at the suggested angle. It says...its' also accurate as to height (ie., place this at the top of the plate ..or where you want the top of the plate to be etc.). But, it doesn't seem to provide proper full angle for the cut....even though it accurately displays dimension/length of the plate. Further, I can't seem to align or combine the 2 in any way that makes sense.

So, do you just use the full (quadrant) template for the cuts..then use the other one to find depth? Or are they supposed to line up in some way?

Not making much sense....and I'd at least like to have some kind of guide before I go hacksawing on it

[Azframer]

If you are using 2" pipe you should be able to find 3 of the 4 quadrants with a framing square and a torpedo level marking top and sides with @ 1". For 30 degrees you would be 9/16" lower at CL of pipe.
Edit= your pipe should be level to find quadrants.

[Usge]

Ok...when in doubt..jump in with both feet and just use more solder Anyway, got it done tonight...frankenstein style...but it's done. It wasn't pretty, but everything lined up properly and I think I finished up a proper boka! Free handing a hack saw on this didn't work out well. It cuts good with one blade, but is very hard to control the angle, and even more difficult to watch both sides as it cuts at once. (pitch was off, one side looked good, back side was off, etc). It also leaves the slot far to thin. Using 2 blades is even harder: it doesn't cut well and was just as hard to control. But the dremel tool turned out to be the shitznit just as soon as I got a template taped up good and found the right disc/speed to use.

I used 2 copies of the bottom curve template overlayed on top of each other. Place the top one and tape it in place. Then, cut the 2nd one close to the curve (so it doesn't cover the one under it). Use the dotted quadrant lines to line them up and make your bottom/take off plate curve. Measure the bottom one to be .75" below the other and tape it in. Although the middle template showing the gap was helpful to see..I didn't use it..as it does not show the full apex of the curve you are going to have to cut. So, just use the bottom template (full curve with dotted lines for quadrants) and overlap them...cut as needed.

Once it was taped on, I used the printed quadrant (dotted) line in the middle on both sides to make your end/stop notch. Just go 1/8" past the middle quadrant line for each plate and put a mark there. That's your stop point along the curve so that it will give you the recommended 1/4" plate overlap.

While your template was still taped to the column, I used the alignment of it to mark the therm well port and take off port for drilling. *TIP: Drill these holes "before" you install any plates

I also annealed the tip on the take off plate that was to be bent down before I put it in. TIP: (repeated from earlier) Don't bend it before you install it. And install it (the bottom plate) FIRST. Then use a long rod to push it down, and in so that it points straight down.

I used a new model dremel at 15K rpm with re-enforced cutting disc...the black ones. It helps to score the line before you are going to cut it, but it's not necessary. It leaves the slot a little ragged, but it cleans up fine with a file and a little solder will fill in any small spaces/uneven areas.

I cut the basic shape of the plates with metal shears..using the flat edge of copper plate I had for the front/leading edge (ie., so it was straight). They fit firmly in the slot...I soldered them in, then filed down the protruding areas with a large flat file until it was flush. Then touched up solder for any holes/gaps, etc.

Like I said...it ain't pretty, but everything lines up proper. I've got rest of what I need to complete the head (valve, etc). Still have to wait on my boiler (backordered). But, in the meantime....I'm off to mock up a 2" potstill head. Cheers!! Usge finally gets a boka!

[Braz]

Looks pretty good to me. Good thinking on anealing the bottom plate before bending the tongue down.

[Usge]

btw, here's a revised 2" template that I made from the previous one that simplifies everything and takes into account all the various suggested mods and other attributes mentioned along the way — both curves on "1" sheet already aligned and spaced .75" apart, cutting stop points on both curves for proper .25" overlap, drill points for take-off and therm well tube, separate upper and lower plate templates with an extended, pointed tip for the lower plate. Just make sure to print it at 100% (without any scaling) so it comes out proper size.

BokaTemplate_rev.pdf

2" Revised Boka Template

(45.69 KiB) Downloaded 34693 times

[hoody]

Usge, I pretty much done exactly as you did. I too was a little confused with the original template's, so good on you for making some clearer one's!
Nice work on the build by the way, looking good.
What size thermo port have you used and how are you planning on "sealing" your probe?? That's the little "issue" i'm trying to sort out at the moment.

hoody

[Usge]

Hoody, I'm using standard 1/4" nominal rigid tube for both the take off and them port....instead of the 1/4" OD coil I used for the reflux condenser. I have a digital therm probe..and my plan is to use cork to seal it with.

[Azframer]

Looks nice man!

[Stimson]

i have made a bokakob with the top condessor section removeable from the column section. Have been using it successfully for 12 months now.
Can we use this style of still for stripping runs? Can I leave the column attached with packing in place and just open the valve wide open?
or do i just attach the condesor section direct to my boiler without the column section?
or do I just need to make a pot still attachement?

Only want it for stripping runs at the moment. No pot stilling....

[Braz]

Any of those options would work. But, you are likely to get some reflux if you are knocking down more vapor than the valve can handle even wide open. For that reason I think I'd either remove the packing or maybe substitute a short (maybe 12") pipe in place of your reflux tube.

I went with option three and built a separate pot head with a liebig condenser.