Let the Vacuum Oven Fun Begin!

[cope413]

We just got a new toy at the office...

a shiny new 1.9cf vacuum oven.

It will pull 30" of Hg and get up to 572F

Preliminary testing with cups of water were fantastic, and by our estimation, we should be able to dry 1lb of fully saturated nylon in less than 30 minutes with no heat stress on the filament.

We'll begin testing and experimenting, and soon we'll offer vacuum drying as an add-on for filament.

Let me know if you've got anything you want to see tried/experimented with

Eventually we'll test every filament, but first to be tested (dry vs wet, how much water, how long to dry, etc)
Nylon (all versions)
TPE
TPU
PC
Tritan

[Eaglezsoar]

What temperature would you use to dry the nylon?

[teoman]

I did have an experiment. But since i moved house to a crummy shithole in the middle of the city. Experimentations have halted.

So my idea was about acetone polishing.

Instead of a heat based method, the one could apply a voccum to get it in vapor.

[travelphotog]

I am looking forward to following this post closely. Please keep us updated. I had been thinking about a vacuum drying chamber but had not pulled the trigger yet. I am looking forward to seeing the results.

[cope413]

Eagle,

Water boils at ~80F when under 30"Hg vacuum. The trick, we are discovering, is getting the filament (and thus the water in the filament) up to temperature before pulling vacuum. There isn't good (or really any) transfer of heat under vacuum, so as long as the filament is above 80F before the vacuum is applied, the water will boil and evaporate.

We'll have some results this week that we'll share.

[jeffhuber]

awesome!! cant wait to hear what you find!

[lightninjay]

Eagle,

Water boils at ~80F when under 30"Hg vacuum. The trick, we are discovering, is getting the filament (and thus the water in the filament) up to temperature before pulling vacuum. There isn't good (or really any) transfer of heat under vacuum, so as long as the filament is above 80F before the vacuum is applied, the water will boil and evaporate.

We'll have some results this week that we'll share.

I've got it! Put the vacuum oven into a bigger oven to keep the temperature at 80* before you pull the vacuum!

[rpress]

So how has it been working? I've been thinking of getting a dryer myself. How long do you soak for and at what temperature? How long do you need to keep it at vacuum?

[Proto]

Ok, when I first saw title to this post I thought... Chocolate Cake!


Sorry, I haven't had breakfast yet, and I'm a bit hungry

[Mac The Knife]

Mmmm. cake. Maybe not so much for that, but I wonder how it would do making beef jerky.

[dtgriscom]

Mmmm. cake. Maybe not so much for that, but I wonder how it would do making beef jerky.

Make a nice lemon meringue pie, and then desiccate it. For the next time you go hiking and want faux gourmet cooking.

Or, make a fruitcake that will truly last forever.




Or not.

[Eaglezsoar]

We just got a new toy at the office...

a shiny new 1.9cf vacuum oven.

It will pull 30" of Hg and get up to 572F

Preliminary testing with cups of water were fantastic, and by our estimation, we should be able to dry 1lb of fully saturated nylon in less than 30 minutes with no heat stress on the filament.

We'll begin testing and experimenting, and soon we'll offer vacuum drying as an add-on for filament.

Let me know if you've got anything you want to see tried/experimented with

Eventually we'll test every filament, but first to be tested (dry vs wet, how much water, how long to dry, etc)
Nylon (all versions)
TPE
TPU
PC
Tritan

2014-10-24 18.52.56.jpg

When the filament is heated while under a vacuum, am I correct that the water in the filament turns to steam (hydogen and oxygen gases) which then go through the vacuum pump and dissipates to the room air?

[dtgriscom]

When the filament is heated while under a vacuum, am I correct that the water in the filament turns to steam (hydogen and oxygen gases) which then go through the vacuum pump and dissipates to the room air?

The water turns to steam/vapor, but that's still H2O; it doesn't disassociate into hydrogen and oxygen.


Dan

[teoman]

Vacuum lowers the boiling pressure of the water. So you can get water to boil at any temperature you want. This is the inverse of a pressure cooker. If you apply pressure (or do not let the pressure of the evaporating water escape) then you can cook your food at a higher temperature which shortens the time.

You heat the filament before you apply a vacuum, because vacuum (or the lack of material) is a fairly poor conductor. So it is difficult to heat or cool stuff under a vacuum. (Cooling electronics is difficult in space and necessitates special measures).

But you are not correct in the sense that the gas is still water vapor which is H2O, the hydrogen and oxygen does not separate. If they did, then that would be pretty dangerous as it might cause an explosion. Or you would be able to easily harness some hydrogen.

[Eaglezsoar]

Vacuum lowers the boiling pressure of the water. So you can get water to boil at any temperature you want. This is the inverse of a pressure cooker. If you apply pressure (or do not let the pressure of the evaporating water escape) then you can cook your food at a higher temperature which shortens the time.

You heat the filament before you apply a vacuum, because vacuum (or the lack of material) is a fairly poor conductor. So it is difficult to heat or cool stuff under a vacuum. (Cooling electronics is difficult in space and necessitates special measures).

But you are not correct in the sense that the gas is still water vapor which is H2O, the hydrogen and oxygen does not separate. If they did, then that would be pretty dangerous as it might cause an explosion. Or you would be able to easily harness some hydrogen.

Thanks for your reply.

[RocketMagnet]

Your lowering the pressure below the vapour pressure of the liquid at a specific temperature.. in this case water.
So with the correct vacuum you wont need any additional heating above room temp at all - with 30" Hg pulling just the Vacuum with no heating should be more than enough ???

Also IMO it's not just a simple case of heating up the filament then applying a vacuum (well decrease the pressure) as you'll need to control the rate
the pressure reduction is applied. You wont want the water to be removed too quickly as it could damage the filament structure. Clearly it's material specific but blowing lots of small holes with a variable distribution in your filament probably wont be beneficial.
Without access to a powerful microscope your only really going to know if any of the physical attributes change (e.g it becomes less pliable/brittle etc).

So it's harder than it sounds IMO so much respect to cope143. I think it will be a fantastic process for Nylon and most other material types with the right temps and rate/level/duration of vacuum. Like others here really interested in your results...

[teoman]

http://www.engineeringtoolbox.com/boili ... d_926.html

[teoman]

How many bars is 30 in Hg in relative vacuum?

when i look it up it is 1.015 bars. But that cant be a vacuum because you go below 0.

[Durandal]

Just a thought for heating the filament inside a vacuum, how about a heat lamp, infrared radiation will pass easily through the vacuum and be absorbed by the filament/spool.

[precisionpete]

From looking at the chart there is no need to heat.

The main thing a vacuum system pumps and removes first is water vapor. Then all the other gases in the system.

Any results yet?

[teoman]

With IR based tech you are only heating the outside of the filament. As vacuum is a good insulator you risk over heating some spots.