looking for advice on Custom wiped film evaporator build

I’d like to start producing my own crude and realized that I already own many of the components of a stainless steel wiped film evaporator.

I have access to CNC equipment, laser cutters, and a friend who is skilled in both CNC and welding stainless who is interested in helping with the project (living in a shipbuilding town in Wisconsin has a lot of drawbacks but all of a sudden seems to have a lot of perks as well) I am assuming that the heating system for the jacket could be done via an immersion circulator heated bath and pump.

I have a limited budget and am trying to avoid buying any chinese made stuff that will break on me.

I figure that the heidolph RZR 2102 stirring unit that I already own, coupled with a cheap rotary vane pump capable of 28inhg, and chiller system, three peristaltic pumps (one to pump in saturated ethanol, one to pump out crude, one to pump out saturated ethanol) - I just need the body of the still, condensor, cold trap, and the stirrer rod fabricated- I can get PTFE sheets and laser cut the gaskets and wiper blades, etc.

I am trying to make a unit that can process 5+gal of saturated ethanol per hour, what diameter chamber and what length, would be necessary for this input? what size wipers?

Also am I stupid to think that I can just put one of these together myself? They don’t seem to be incredibly complicated at first glance.


if it looks like you can build it, especially with parts on hand, I suggest you give it a whirl. and document your progress.

most are using their WFE for distilling cannabinoids not ethanol.

a pot still will remove the liquor way cheaper.


I’ve been told that one can expect about 10-50L/hr from a 0.5m evaporation surface on a wiped film if you’re just stripping off the ethanol. Most WFE units I’ve looked into tend to have something like 4-6 wipers on them.

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I would like to design a system that allows me to control decarb and overall reduce temps, pot still is cheap but I want cbd-a as a potential output of this system.


0.5m means a half a meter?

Sorry it should be 0.5 m2, half a square meter.

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This system can be built pretty easily using existing resources avail that are normally marketed to BHO extractors- I thought I needed to get a lot of custom work done but working with tri clamp SS parts is not too expensive, best value vacs has almost everything necessary and even has a sale on individual stainless parts right now.

I’ve put together a plan for a 36" X 8" SS wiped film evap system for approx $4k- this seems shockingly cheap, There are a few parts I need to have made custom made for this but even then it seems like I must be missing something.

does anyone here know much about mechanical seals on these units, and what I would need to run a 10mm wiper rotor powered via aforementioned heidolph stirrer unit into an 8" still?


Chk out ferrofluid seals. Ferrotec is s good choice. Vacuum rated mechsbical seals. Sounds like a good project. Keep us informed on progress.


Great advice on the ferrofluid seals, they are the right size for this application and can be found cheap and in like new condition via ebay


It does. But now that you’ve laid it out and I’m actually thinking about what is involved with these, they aren’t that complicated on the hardware side. The tolerances will need to be pretty tight, and as such they’re gonna be finicky, but overall the individual parts shouldn’t be that difficult/expensive to manufacture. Hm.

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so far i am planning on an 8in jacketed tri clamp 36" long with a jacketed hopper, a ball valve will regulate feed input.

I figured out how to run an internal condenser into this thing while i was in the shower this morning- im hoping that I can go bio to distillate in one unit. atleast until I can afford to get a second one running that will just process out the ethanol.

the most complicated part is getting the internal condenser and distillate drain arranged- im going with a 3inch ID with a 1In jacket, the inlet and outlet ports have to both come from the bottom lip of the jacket as to not interfere with the wipers- so a long tube has to be run to the top through the jacket itself for the condenser outlet.

This leaves approx 38mm for wiper blades. im looking at cutting down a .25" stainless sheet into 32mm strips, then sending those to be coated with a 3mil PTFE layer, total size is 9mm by 38mm- the diagonal channels in the wipers can be cut with a laser cutter 2mil deep. ends will be polished to fit inside precisely.

the wiper assembly will have to be custom CNC pieces welded together and tapped to fit the thread on the driveshaft, not really difficult at all.

I’ll upload some drawings and a costing sheet if anyone is interested.


the 3mil teflon coat could also be super precisely sized to fit the dimensions of the tube with the laser cutter/etcher.

Please do!

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Hey great project man!

Having access to fabrication/machine shops with willing operators is priceless. I have no doubt you can get one of these up and running.

I’m confused about your intentions. Are you making something to recover bulk ethanol from the post-extraction solution or something to distill cannabinoids from crude?

The main idea behind a thin/wiped film evaporator (both internal and external main condenser designs) is to minimize the residence time of thermally sensitive products. The internal condenser design (short path) is meant to allow higher vacuum ranges to get the lowest possible boiling temperature.

To recover ethanol after extraction you won’t need to use temperatures high enough to degrade the cannabinoids at a high rate so residence time in the still isn’t really a big issue. This makes it hard to justify the complication/expense of a wiped film design, either internally or externally condensed.

If you used an internal condenser design for recovering bulk ethanol you would likely overload the condenser quickly and any type of bubbling/bumping of the solution, which is common, would contaminate the clean ethanol very easily. An external condenser design would probably work as a replacement for a rotovap but isn’t really the best tool for the job and rotovaps are already relatively cheap and plentiful. Once you are at large scale you would run into the same issue as rotovaps in that you would need to use so many separate wiper units to keep up with production you would quickly want to replace them for a tube-in-shell evaporator system because it is way more efficient from multiple stand points.

If you were on a medium to large scale and needed hundreds of liters per hour recovery I would suggest attempting a falling or rising film evaporator build instead of a wiper.

If you really just need about 5 gallons per hour recovery like you mentioned, a 50L rotovap with a good solid chiller (4-5Kw @ 0C) should be able to fit the bill just fine and will probably cost less than the money you’ll spend on this project.

If your aim is to distill cannabinoids from crude I think you are headed in the right direction with the internal condenser design. I will include a couple pics of proven condenser designs you can work off of. Maybe @Future can chime in about the ferrofluid seals, I know the Skunkpharmers were using one when they almost had their Terp Trommel project up and running.


Thanks for the quality post!
My goal here is to start processing with a low initial investment and high throughput ability- The design I currently have sketched out has a removable internal condenser- there is an external condensor and collection flask followed by a cold trap. The idea is that I can use this unit to produce crude if I have biomass available and if there is ample crude I can use it to distill CBD. Once I am able to afford rotovaps/ffe I would use this only as a distiller.


upload sketch ,i am curios to see it too
also i saw somewhere i will try find ,it was seals available around 300-400 area , i will dig trough my emails to see if i can find it for you

These are VERY rough sketches, concept art even- I am ditching the external condensor completely and that is still pictured here- I have a very clear image in my head of how this will all come together and am working on getting a CAD liscense so I can make it ultra refined and clean.

I am in the process of opening a bar, building a curing/incubation chamber for curing old world style salumi and making miso, and have decided to go ahead and build out a 2L SPD for hands on learning ins and outs of CBD distillation before I start building this WFE- this has taken a bit of a backburner as I realize I just don’t have the feedstock right now (still have a few weeks to decide on whether I will be growing hemp in 2019) but I will continue to refine the concept as time/resources for it becomes available.


You can simplify the build out a little if you don’t mind pinching your vapor path a bit… Offsetting the cold condenser allows for a much more simplistic arrangement of your receiving vessels… You’ll haveta run a little hotter but its still a short enough residence time that it shouldn’t make a difference.



I am specifically seeking to make a unit that can distill high-CBDA so residence time is important, but as far as I can tell running undecarbed material may cause an increase in bubbling and splatter so contamination of internal condenser may be an issue-

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You can suck on a pot till and fail to decarb…

Aka “vac assist”

So you’re planning to use it for solvent removal, and then for cannabinoid distillation? And hope to get cbda out?!?

:thinking: seems like some to settle in and watch … :popcorn:

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