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SoliForum - 3D Printing Community → Hacks & Mods → Vacuum sealed print chamber
I was just thinking, it would probably make sense to print in a vacuum. That should almost eliminate completely any warping.
I can imagine the difficulties involved, but why not?
I would think it would rob heat from the chamber and the bed and hotend heaters would have to work harder to make up the ambient atmosphere.
My thought.
Then again, I know some users have discussed using this method, but more for concern of smell. I don't know what there resulting qualities were though.
Well a vacuum is an almost perfect insulator, without a medium for heat transfer, it should work exceptionally well. That of course means water cooling instead of fans, but that works better as well.
Not feasible.
14.7 psi * 12" * 12" = 2100lbs pushing on each wall. The chamber would be very expensive, as it would need to support the weight of a car parked on top of it.
You wouldn't save power over a enclosure heater since you'd have to run the vac pump, and you'd have to wait for some time while it pulled a vacuum.
You gonna watercool all the steppers too?
Given those forces involved it would be easier making a chamber to fit a printer into.
I'm not looking into it for cost savings. This is purely just curiosity on how it would affect the print itself. That's what I'm interested in, a better way to maintain accuracy.
Yes, water cooling the components would become necessary.
It would provide no advantage over a heated build chamber, which is why Stratasys uses a heated build chamber, not a vacuum chamber.
If you care about accuracy, you should be in pursuit of gantry stiffness. If part warp is an issue, then change the polymer or heat the build volume.
That's more likely the case that's it is much much cheaper rather than there is no benefit in comparison. I think it would provide a much more even temperature distribution in the entire part.
Since you mentioned the forces on the chamber, what about the forces on the part after coming out of the vacuum? A hollow part should implode, which would negate all benefits entirely.
That's more likely the case that's it is much much cheaper rather than there is no benefit in comparison. I think it would provide a much more even temperature distribution in the entire part.
Definitely not, you would have a stronger gradient over the part in a vacuum chamber than a heated chamber. In a heated chamber, the temperature is uniform within a couple percent, and the part will be as well. In a vacuum, the temperature would vary nearly linearly from the hotend temperature down to the bed temperature. Also the gradient isn't really the issue, the issue is keeping the whole part above Tg. Possibly most importantly, by using a vacuum chamber, you couldn't have part cooling fans so you'd lose any small details.
Since you mentioned the forces on the chamber, what about the forces on the part after coming out of the vacuum? A hollow part should implode, which would negate all benefits entirely.
Also definitely not. FDM parts are not airtight. Since you couldn't expose the chamber to atmosphere instantaneously (you'd have to let the pressure rise over time through an orifice of some sort), the part's internals would have plenty of time to equalize pressure.
I spend my time doing many things. Talking about things I don't have a fundamental understanding of is not one of them.
I see what you mean. Instead of it holding its heat more uniformly, it would just radiate heat more linearly. Even so, it would depend on the rate it radiates the heat after extrusion. If it's slow enough it's still a more uniform gradient than a breeze blowing through.
On the second point, are you referring to plastic being porous or just that fdm usually has gaps in the structure?
No, a heated build chamber will *always* be more uniform.
In a HBC, the print bed is the same temperature as the build chamber air. In fact, the Stratasys machines don't uses bed heaters. Therefore, all but the top layer or two of the print are the same temperature as the heated build chamber air. There is no gradient (aside from the top couple layers).
In a VC, the print bed is at whatever temperature, lets say 100C. Because heat cannot be conducted/convected to the air as there is no air, and radiated heat is likely negligible, all thats left is conduction to the heat bed. So, the top of your part is ~220C, and the bottom of your part is ~100C - and what's in between has a linear gradient. If you didn't want to neglect radiant heat in the calculation, the problem still stands since the bottom of your part is held at 100C and the top of the part at 220C, with a (nonlinear, due to radiation) gradient in between.
In a HBC, the whole gradient zone (only a few layers) is well above the Tg for the material, so it doesn't really matter since the material hasn't quite hardened yet. In a VC, the gradient extends through the height of the part, dozens of layers thick. Therefore the VC is worse, even before considering part cooling fans not being possible and the added complexity of water-cooling (and construction of a chamber that can handle 1-2 tons of force).
I get what you are saying. Also, if had a great understanding of the topic, i wouldn't have reached out to ask questions and discuss things with someone who knows more about it than i do. I learn a lot from bouncing ideas around.
Back on topic, does anyone by chance have access to a vacuum chamber?
As for FDM porosity, it is generally accepted to be at least air-porous, generally water-porous.
https://www.partsnap.com/3d-printing/3d … tasys-fdm/
It's not the plastic, its the way layers are formed that produces the porosity.
vacuum means no air and no air cooling ability for things that require it
SoliForum - 3D Printing Community → Hacks & Mods → Vacuum sealed print chamber
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