DIY Vacuum Oven, anyone ever tried?


#1

Hey friends,

I was getting into the wonderful world of shatter, and had priced out some vacuum ovens.
When I started to add it up, I realized these would be pretty easy to build.
Instead of an oven I was going to use a heated bath and place small stainless containers with lids into the bath.
I have a welder friend, we’re doing 3/16 steel. I was doing the initial ones in an 8’‘x8’’. Only needs to get the etoh evap temperature down to 30c, so vacuum isn’t too deep. If the small units work, I’d likely do a larger size and build shelves full of them.

I was thinking the benefit of the bath is I’d be able to send vibrations through the bath and increase the potential for solvent evaporation. Either using ultrasonic probe or even something as simple as a subwoofer (bass shatter?!)

I’ll whip up a picture and maybe some photos.

Has anyone ever build a vacuum oven before?


#2

I used heat tape capable of 400° F and wrapped my tall aluminum vacuum chamber in that. I secured it in place with aluminum tape as my own attempt at a home built vac oven. It worked but the truth is I do not ever need a vacuum oven so after a while I dissasembled the unit to use the heat tape elsewhere.

The chamber itself is a tall aluminum pot about 12" in diameter. I use it now really just as a catch all for my dirty glassware and dump alcohol in it so things can soak. The advantage of a very tall unit is the vacuum seal on the lid can be kept relatively cool and still function well because the heat tape is a lot lower at the highest point. My intent was to place the unit on top of my hot plate too so heat was applied bottom sides and top. I never run extractions at all and only refine and the unit was simply too big and cumbersome to deal with < one ounce of compound which is my typical starting point.

Your idea of introducing energy via sound waves is very innovative. :nerd_face:


#3

There are two main vacuum oven heat methods:

1 Radiant, where the inner walls are heated by attached heaters, and the infrared energy bounces around the chamber to be absorbed by what you’re trying to purge.

2 Individually heated shelves, where heaters and thermocouple sensors are encased in each shelf, each with its own PID temperature controller, in this case what you’re trying to purge comes into direct contact with the heat source.

The radiant heat vac ovens need a double wall, the inner wall gets hot, and for safety reasons it should be isolated, also the inner wall needs to be insulated from the outside air to maintain its temperature stability.

But an individually heated shelf vac oven doesn’t have any need for the outer wall!! I’ve posted up repeatedly at ICMAG Forums about this, and have made my case to Across International a couple of times face to face at the cannabis oil festivals.

All you need is a sturdy box that can withstand vacuum.

Secondly, the way they heat the shelves can be way improved upon with little increase in cost compared to the huge prices they ask for these things. Instead of incasing a crude metal heating element in a pocket within the shelf, just use a plain sheet of aluminum or stainless steel for the shelf, and stick a full width and depth silicone heater (heat mat) with attached sensor to the bottom. The silicone heaters can be ordered from Keenova with 3M adhesive backing (simply peel off the protective layer and stick the heater to the bottom of the shelf.) Keenova will also attach a thermocouple to the center of the heater if you want.

Here’s Keenova’s custom silicone heater page at eBay to show you how simple this all is…

https://www.ebay.com/str/Flexible-Heaters/Custom-Silicone-Heaters/_i.html?_storecat=10754111018

I’ve ordered silicone heaters from Keenova with no problems, as described with quick delivery. I have a couple sitting around still waiting to be purposed.

Btw, Best Value Vacs took my stock pot vac chamber heater design which I originally posted up at Toke City Forums, and has been making a profit off it for several years, they call them Digital Heatpads, here’s a link,

https://www.bestvaluevacs.com/categories/digital-heatpads.html

I haven’t asked for a dime for my contributions and never will.


#4

What do you use for a vacuum proof bulkhead to pass the wires through on the heated shelf?


#5

Use an ordinary connector and glob epoxy on it to seal it, or just bring the wires through and seal with epoxy. I’m sure there are sealed connectors that can be had if you’re willing to search for them and pay an exorbitant price.


#6

Yeah I was just thinking a water bath with a sous-vide heater from amazon ($70) would be able to handle the entire system. The single heat source and plug should be able to heat the entire system of however many trays I need. I was thinking there might be a bit of benefit both having the sides warmed while also having very little vertical space to decrease any potential time for solvent recondensing. I think it effectively cuts the cost down to 1/3 of convential vacuum ovens, plus a modular design allows for easy isolating of chambers. I was going to do the lids out of thick plexi but I realized I’d need to layer the whole thing in a teflon pad for etoh compatability, and the costs just started to add up to about the same as doing the whole thing in steel. I tried doing the classic pyrex dish method but I bought on old one and it cracked as soon as i pulled vacuum. Plus, I think avoiding glass is just best for everyone involved. When your oz of product ends up in your water, it pays for 3-4 new steel bases anyhow.


#7

I was looking into doing this myself for a bit and came across this video. Apparently it was a failed startup on Indiegogo, but the concept seems pretty straightforward.


#8

I hate that the acrylics aren’t etoh compatible, I wanna look at my stuff!


#9

Also at $500 price you can get a used multi shelf oven :stuck_out_tongue: these guys haven’t invented much lol. I’m thinking each chamber will run me $120 welded and run about 30-40g per chamber. Less if I just build big ones.


#10

Ooooh yea, there’s a reason their startup failed. But I dig the simple concept for building one myself.


#11

Here’s how to do it for $200
Get a pressure cooker or thick walled pot. ($10 used)
Get a piece of 3/4’’ sheet acrylic ($40)
Silicone Caulk ($10)
Sous Vide heater ($60 amazon)
Larger basin to fit thick walled pot in + water ($10)
Valves/fittings etc. ($60)

If you need it ethanol compatible buy a teflon mat and adhere it to the underside of the acrylic sheet ($15)


#12

I had been toying around with this and also the idea of getting a used one and refurbishing it. Ideally you want to be able to SEE into it which is pretty key. Either you need a camera in there or it has to have glass / acrylic window. Acrylic isn’t ideal for the reasons tweedledew posted. The starter could be a stainless steel sink or cabinet/shelf of the appropriate size. I have been looking on craigslist for stainless steel boxish shaped objects. Add in a door and create a double gasket, one simple gasket on the door and a U shaped gasket over the interior box liner. Outside can be simple sheet steel that is finished. Keeping the temps around normal purging temps I think could be easily accomplished with a couple of heat mats and a PID. If you planned on going higher temp I would do that differently.

These are just a few of the rough thoughts I’ve had…


#13

As @tweedledew mentioned there’s the pressure cooker method for diy and here’s a more expanded explanation on how to construct one, though with some minor differences from the above:

I especially like the addition of a Teflon sheet if working with ethanol. In the instructable I really like that the vacuum is drawn through the pot and not the already ‘risky’ sheet over top, but feel like the copper tubing could easily be replaced with ptfe hosing if its already on hand making the system a bit more flexible to movement.

I really liked this link for a diy Bhoulder:

http://www.highsimple.com/diy-bhoulder/part-2-vacuum-oven-for-purging/

I’m just not sure how I feel about the risk of implosion using a Pyrex dish or from drilling holes in the lid, but it seems like a much simpler build though.

I have to admit neither seem like a vac oven as much as a vac chamber you could heat from below. The oven tech mentioned by @SkyHighLer seems more on the lines of a true diy vac oven. Also, it almost seems like there’d be a negligible difference in cost between building a vac chamber and buying one online.


#15

do you think there’d be much difference between the efficacy of the chamber vs the oven? Obviously the oven would have likely an increased solvent takeoff rate due to the radiating heat? I’m hoping by adding some vibration to mine it would have a similar effect


#16

Exactly!

My first 6 “Vac ovens” probably cost me less than $200 total.
before I added gauges and filters on the inlets.

But I had a 6sq ft chunk of 1" polycarbonate lying around.

I used the 12" stainless pots from from St Vinnies, with $10 pressure cooker gaskets, and heat mats also sourced from vinnies.

purged in 10" pie dishes sourced from you know where.

didn’t always get me shatter.
but shatter ain’t all that matter.


#17

I’m probably not the expert on the matter, but most of the ovens I’ve seen cost so much more than the vacuum chambers, homemade or otherwise that I’m not sure the improvement in efficiency would be worth the additional cost. If we’re talking about increased productivity because you need large volumes fast I’d imagine the pricepoint of the ovens then becomes irrelevant due to the projected revenue.

As for the vibrations, if they disturb the surface enough they should increase evaporation by simulating the effects of heating and reducing the chance for pockets of solvent to get trapped in thick oil, I’d imagine.

Trying to find some data I did come across this:

It might not be relatable, but was interesting all the same concerning heating caused by ultrasonic vibrations and might have implications in other cannabis concentrate processes.

There’s a similar, opposite effect, when it comes to oxygen being absorbed by water more easily when the water surface is agitated that’s employed when setting up aquariums. Not sure if that’s at all relevant, but it came to mind too.


#18

My only concern would be the “snappy-ness” of the extract, so perhaps in turn that would be directly relatable to the amount of solvent remaining.

My welder finished the pilot! I’ll snap some progress pics for y’all when i pick it up on Monday.

I’ve been looking for the ultrasonic vibration correlation forever! I saw it on a forum once and it long since got lost and google never found it for me again!

I was thinking for any oils just to put an ultrasonic hammer into a jar and vacuum and vibe and have my oil evaporated already into the end container ready for sale. I’ll have to run some tests when i get some more $$


#19

Thx so much! I’m gonna email this dude about his findings and see what he thinks.

Even an ultrasonic pad (found some on alibaba) inside the oven (pending on etoh compatability), might be a pretty rad way to speed the whole thing up. If I could take oven times down it’s almost always going to be a bottleneck!


#20

I just saw this and thought it might be worth mentioning when considering what material to use for your vac chamber if using vibrations.

He mentions it in the Tricks of the Trade post.


#21

I was thinking about doing an infrared bulb/element on the lid of the stainless chamber to reap the benefits of the radiant heat through vacuum. Any reason this wouldn’t work? Does it penetrate through the steel easily?