Vacuum Slow Cooker Filament Restoration




Introduction: Vacuum Slow Cooker Filament Restoration

About: Greetings from my laboratory! I am usually out here working on projects and solving problems. Sometimes for the profit, often for the challenge, but always for the love... and I absolutely love this s***! ...

This instructable will show you how to modify your Crock Pot to cook up some deliciously fresh Filament!

As we all know, over time, moisture can get inside of our filament. Slowey turning our favorite rolls into brittle garbage. We store them in safe places, take time to care for them like children. But, in the end, they often turn into the sad shell of the former glory they once provided. Sad but true, makers in tropical climates have but only one option, Print as much as you can, as fast as you can, before the roll has passed on to the shelf of worthless money. To valuable to be tossed aside, yet to brittle to be put to use.

One day, we heard a rumor. Filament can be put in the oven and baked bake to life. We felt overjoyed, so many colors sitting on the shelf waiting to be brought back to life...But it was mostly a waste of time. Some rolls seamed to be printing better, but not like before...before the moisture. We put our filament back on the shelf and accepted our fate...


-The Negative Atmosphere Crock-Pot Heating Method-

The problem with most attempts and devices used to dry filament is; they rely on heating the filament to a high temperature for a long time. As the moisture leaves the filament, the filament is often distorted in the process, losing all of its precious dimensional accuracy. So, even if it works in drying it out, the filament will often perform poorly because of its now, inconsistent shape.

To solve this, we need less heat and less atmosphere!. By pulling a vacuum on the inside of the Crock Pot, 100-150 degrees Fahrenheit becomes more than enough temperature to safely dry our filament!

By following this instructable, you will finally be able to bring those filaments back to life!


I may be offering a product in the near future based off what will be explained here. Consequently, the patents are pending. Feel free to contact me regarding licensing.

Step 1: What You Will Need

1 - 7QT Crock-Pot - I used a 7qt Classic brand name Crock-Pot. Its a great price and big enough to fit any of my filaments, it does the job perfectly

2 - Device that can pull a strong vacuum. I used a MityVac brand handheld vacuum.

3 - Hose that not only fits on your vacuum, but also the nipple on the bottom of the Crock-Pot

4 - Silicone Tape and some Silicone caulk (I bought mine at the hardware store)

5 - Petroleum Jelly or Silicone Release agent. This is used to coat the lid when making the seal

6 - Old Filament that just wont print right

Step 2: Remove the Removable Stoneware

Take the heavy stoneware bowl out, we wont be needing any of that here.

Step 3: Attach a Hose to Pot.

On the inside of most Crock Pots are one or more holes that are used to keep the bowl empty of liquid. Flip the pot over and you will see a little nipple. Attach the hose to the nipple you wish to connect to your vacuum, use a hose clamp.

Step 4: Seal the Remaining Holes

Now, use some silicone to seal the gaps around the holes and on the lid(where the screw is found). Take note of which hole you have connected to the hose. Fill the other hole with silicon to seal it shut. Remember leave the hole that is connected to the hose free of obstructions. On the outside, I use a hose clamp and a piece of silicone tape to seal the second hole even more.

Step 5: Apply Silicone to the Inside Top of the Pot

This will be our custom air tight gasket. Apply Silicone to the inside of the Crock-Pot.

Step 6: Put Petroleum Jelly on the Lid

Put a bunch of the jelly around the edge of the lid. This will act as a release agent so that the lid can easily be removed from the dry silicone.

Step 7: Carefully Place the Lid Onto the Pot

The Silicone will dry and make a perfectly fitting seal for this lid. You can lightly blow into the air hose to make sure it seals correctly. Don't blow to hard, just enough to see the lid rise a little bit.

Step 8: After 24 Hours, Its Ready to Use!!!!

After it is dry and holds a vacuum, you are good to go!

Step 1 : Place a bad roll of filament into the Crock-Pot

Step 2 : Set the Crock-Pot to "Warm", let it warm up for 10-15 min

Step 3 : Connect your Vacuum line to a vacuum and pull a few kpa (-5 to -10)

Step 4 : If it is NOT leaking, we should put a piece of floss in between the lid and the seal. The movement of air is necessary for evaporation at less than boiling temperatures.

Step 5 :Increase the vacuum incrementally. be careful and wear eye protection. at -40 Kpa, you could have 400lbs pulling on the lid. You need enough vacuum to help the water evaporate from the filament, but you don't need to make it a total vacuum! You will get a feel for it as you use it. Safest way is to start out with a higher tempature and less vacuum. Something like -20 Kpa and 180F and see how it goes.

Step 6 : Enjoy your filament's second life!

Next time I dry some filament I will run tests to get quality data.



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    21 Discussions

    I did a variation on this: I found a slow cooker in which the ceramic pot was large enough to hold a reel of filament. Then I took the handle off the lid, it was held on by a screw that went through the lid, and epoxied a manual valve to that hole. To use, I hook the vacuum pump to the other end of the value and pump. After I get the requisite pressure, I can shut off the value and remove the pump. That's the theory at least.

    In practice, my silicone goop hasn't made a decent seal against the lid (verified by putting a of water at the rim of the lid and pumping). Any suggestions for getting a better seal?

    1 reply

    Yes, I'm actually preparing to post V2! Most of the components are the same, but might have to order a few extra things. Currently, I am quantifying data and fine tuning the process! -spoiler alert- You are going to love the results and find this one much easier to build. In the meantime, you can follow me to get updates as soon as I post them- but I will try and remember to send you a message :)


    8 weeks ago

    Interesting Crock Pot recipe ! You might consider applying some "spokes" of fiberglass strapping tape to the glass lid just in case, not to help with the seal but in case the lid fractures.

    1 reply

    I will be posting a 2.0 shortly. Not only will it feature many of the improvements suggested by users, It will also included quantified data!

    The only kind of filament I'm familiar with is monofilament, such as is used for fishing line. Having read through the whole instructable, I eventually deduced that wasn't what you meant but you might be referring to 3D printer filament, which I only know about vaguely, and it wasn't till I got to almost the end of the questions before that was confirmed. It would have been the easiest thing in the world to specify that at the beginning; I always feel short changed when writers assume everyone knows as much as they do about the instructable's topic...


    Question 2 months ago

    Have you weighed a role before and after?
    Lets say you have a 1KG spool sitting around a humid environment for months, it's possible to absorb 1% water by weight (source below). 10g of water would be measurable on just about any modern scale.

    Has anyone tried weighing a new spool of ABS, then weigh it after it's been submerged for a month to see how much mass was gained? Would be very interesting to know how effective this method is at removing water.

    Lastly, do you get the crock-pot hot first (while there are the most air molecules in the pot to heat the filament evenly) THEN pull the partial vacuum? Or do you pull vacuum and heat simultaneously?

    Be careful! Is the glass lid of the pot rated to withstand the vacuum force? It could implode! (If the pot is 10" in diameter, the force on the lid with high vacuum is about 1000 lbs! Even with -40Kpascals-vacuum, it is still 400lbs.)

    What I would do is to draw vacuum, but also have a small leak that slowly admits air to the chamber. The moving air at low pressure will carry away the moisture better than still air. Without air circulation, the boiling point of water must be exceeded to get water transport out. With your -40kilopascals, that's only a 40% reduction in pressure. Boiling point of water is not even reduced 10C (so you would need to get hotter than 90C to drive off water). By bleeding air, any water that evaporates from the filament will be swept away. Better is to set this up so the bleed air comes from an area with dehumidifier running. At 120F, vapor pressure of water is only 0.12 atmospheres, so you would need -90kilopascals without circulation.

    I don't have a crock pot but I do have a pressure cooker. Think that will work just as well? It has various temp settings including Low.

    1 more answer

    Yes, somehow you would have to install a suitable nipple or valve for which to connect the vacuum pump. Care would have to be taken to ensure that it is capable of achieving the required amount of vacuum. However, pressure cookers experience fairly high amounts of pressure during intended operation. I would strongly advise that you never attempt to use the pressure cooker for anything other than drying filament if you decide to make these modifications.

    Do you have any idea how much of the roll of filament is dried?

    In other words, the sides of the reel are solid, so no moisture is exiting through that, and the filament is wound up so that could prevent inner turns of the filament from being able to breath and dehumidify. Have you done any experiments to determine if just the outside turns are being dehumidified or if the effect goes all the way to the core or something in between?

    1 more answer

    This is one of the reasons the vacuum is such an important part of the process. Other than allowing for more efficient evaporation; a vacuum allows for this evaporation to take place on almost all of the filaments surface, as the filament is not wound tightly enough to completely prevent the movement of air.

    Brilliant hack! I have a general question about filament and storage in general. If moisture is an issue, can you store your filament with desiccant and hopefully prevent it from absorbing moisture in the first place? I'm saving this instructable just in case!

    1 more answer

    Yes, and most of us store our filament like this. I would even consider myself one of them lol. However, as I live in a tropical climate, I find that all of my filament performs worse as time goes on. Regardless of how much care I take,there are short periods of time when my filament is exposed to pretty high amounts of humidity.


    Tip 2 months ago

    Brilliant idea. Thanks. Consider using a slice (3in or 75mm) from a car tire inner tube to wrap over the lip of the crockpot instead of silicone goop. This gives a good seal and is easily added/removed. (Cutting the loop on an angle lets you make wider diameter tubes than the the tire.)

    Brilliant! I'll be making one.

    3D printer filament.

    ABS and nylon tend to absorb humidity from the atmosphere.

    This is heard as tiny pops when the filament is extruding/ printing an object.


    2 months ago

    This is a very creative use of a crock pot! Excellent tips!

    1 reply

    Thank you, I'm glad you enjoyed it! If you live in a humid environment like myself, it will be very helpful.

    How long do you leave the filament in the crockpot under a vacuum? Or, how do you know when it's done?