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Humidity while printing (and build enclosures)

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  • Humidity while printing (and build enclosures)

    I've been having some difficulties printing, less so now as we move into the summer months but my workshop rarely gets above 18 C (65 F) even in the height of summer, so I figured since I'm working on a very large project - 5/6 1 Kg spools of PLA, which is a lot for me - it was time to insulate the platform and save a little bit of power.

    My current setup is an Ender 5 Pro with the excellent Klipper software running on a RPi3 and absolutely blowing me away with the speed. I've even done some successful prints above 200 mm/S which is fairly fast on a consumer printer with a stock hot end! I've had to do a fair bit of tweaking in the slicer so that I didn't knock the print clear out of the room (think lots of Z-hops, slower travel moves and so on) but in spite of all that, less prints demanding prints (cylinders and similar) have come out perfectly acceptably and at least as good or better than Marlin managed at 60 mm/S

    My "Heath Robinson" enclosure simply consists of a couple of those foam and silvered plastic things you put in the car windows to stop the place turning into a greenhouse when you're parked, taped up and propped with some garden cane. So yeah, VERY, VERY bad.

    But in spite of all that I've consistently managed to maintain temperatures around 10-15 C higher than ambient because the silvered layers hold in convected heat but reflect radiant back. It's obviously not as attractive as having a glass or perspex affair but the efficiency is astonishing for something I threw together with my son-in-law-to-be in about 10 minutes. Once this project is done, I'll revisit it and clean it up. Right now for instance, the whole thing has to be lifted clear - web camera, lamp, Uncle Tom Cobley and all, to retrieve the print.

    What is interesting and I wonder how much this affects printing, is the relative humidity in the enclosure vs. RH outside. Warm air can hold more moisture than cold air (which is why static electricity tends to be worse in the winter) and the RH in the workshop is regularly hitting 70% at 18C which isn't high for some parts of the world, but it's fairly moist for here. Conversely though, the RH in the enclosure is hovering below 35% at 35 C (measured, accuracy +/- 1C and 2% RH).

    The other effect of an enclosure is that less dust gets in although that's likely a minimal effect and I've not attempted to measure it.

    TL;DR

    One effect I've noticed is that the more stable temperature seems to be preventing warping, an problem that had plagued me no matter what I put on the build plate. I've set the build plate temperature at 30 C but the thermometer there indicates that it's often a little above that. In spite of being well below the recommended 50 C, nothing has warped (yet).

    Could the lower humidity be helping the print stick or is this more likely an effect from the more stable temperature (and, naturally, lack of drafts!)? Further, I wonder if the reduced humidity could be having an effect on layer adhesion? I don't have an easy way to test this (I guess Stefan at CNC Kitchen might) but this while PLA isn't a major problem so far as the hygroscopic effect, other more "tricky" filaments might.

    I'm really just spitballing here with my own thoughts and experiences, but I can say that save for the odd problem I've probably caused with my fiddling, these prints are superb and polish off with wet and dry to a beautiful sheen in fairly short measure.

  • #2
    In my experience temperatures below around 20°C cause parts to lift and even methods like glue start to fail.

    Humidity is not a big problem here in Germany. I have about 20 spools in the opening (ABS/PLA) for years without any issues. Only the ambient room temperature and drafts (open door or window) are creating issues while printing for me.

    So in your case an enclosure will even help with PLA, as the heat bed and the nozzle will heat the chamber on their own. Along with a little preheat period of your printer (which is always a good idea) this will improve the print quality massively.

    The build plate temperature should be around 60 to 65°C when no other adhesion method is used. This is perfect for glass with or without glue. Other build surfaces allow lower temperatures, but I never printed on anything but glass, so I can't know.
    Last edited by Geit; 06-04-2021, 05:59 PM.

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