Pushing my heated chamber temperatures to the limit

  • Sounds good with the insulation.

    Yeah these propellers are designed to mount the motor outside.
    I am also thinking of buying many mini DC motors with a long shaft and moderate speed, mount them just like the oven propeller (motor outside, fanblade inside) and stick self printed fanblades on them (like 50 mm ones). Two fans in every edge to get a good air circulation.

    But first I will try the insulation.

  • @christoph13524
    This is what I'm using, but 45-50C is much easier to deal with. I'm probably at the thermal operating limit of the fan, but it's an industrial unit, not a PC cooler or hobby part.

    alt text

    Since this photo was taken I've added a heat shield for the Z axis motor. I'm going to add a cylinder of wire mesh to cover the heater and electrical connections to keep fingers and print debris away from the heater bar and electrical contacts.

  • @christoph13524 I read recently that it's easier to construct a 150-90-50 °C solution than a 150-50, i. e. to encapsulate an inner chamber by a middle layer, then outer.

    There are some people who print PEEK, maybe you get hints from them also. They use a chamber of 80 °C (and higher, 200 °C).

  • @mrehorstdmd
    Clean look!
    Noctua fans can withstand temperatures up to 70°C according to the email support.
    And all other common fans can be used up to those temperatures I think so. Depends on the plastic it consists of. As I see, your fan has an aluminum frame, so don't carry about your 50°C hot chamber.

    I can basically put my enclosed UMO+ in another big enclosure but that is not what I want. That's way to complex.
    I will see how the PIR sheets work. Maybe they will do the job.

  • @christoph13524 said in Pushing my heated chamber temperatures to the limit:

    Interesting to hear that a better insulation would be that much more effective

    All is about insulation! You can't reach target temp because loss are too high regarding the input power. Reducing loss, and you don't need such high power.

    If you have a infinite insulation, then, once heated up, you don't need anymore power to keep it hot ;o) Same as supra-conductive wires: no more Joule loss.

  • If you want a real stable temperature u need to have more isolation.

    Make a hot airflow like a oven inside the inner chamber (heated one). Make that chamber isolated with some high temp material or use basic rockwool.

    Next let cool air flow on the outer chamber to leave the outside of your printer cool so you can touch it.

    We build a machine with 1m x 1m buildvolume and 200 degree chamber this way. Little bit more complex but for 90 degrees it's almost the same. If you need more help please contact me.

  • So I bought some insulation material and have installed it.
    I didn't got the recommended PIR-sheets but some other 11 mm thick foam with quite good thermal insulation values which is permanently temperature resistant to 200 °C. This stuff was really expensive: 100 € for 2 m² foam.

    I have isolated the top cover completely and the side panels. I really don't want to isolate the front panel because then I can't see anything 🙂
    But the foam works really well. Now it got me a maximum temperature of 82 °C and the PC-panels are much cooler. That's 8 °C more than without foam.
    But the thing is I only reached that temperature with a heated bed at 130 °C which is too hot for ABS. With a headed bed at 100 °C I only got a temperature of 77 °C. And it took 1 hour to reach that - so quite long.


    Things I am going to do now:

    • Putting that magic foam everywhere I can. So also on the wooden panels and some other places. That will probably finally give me 90 °C with a heated bed at 130 °C. But with a bed at 100 °C it still won't.

    • Installing a second chamber heated above the first one. This will definitely give me my desired temperature and will drastically decrease the heat up time as well.

    But I am still thinking about my first question in the main post: The thing with an exhaust fan and airtight chamber.
    On the one hand the foam got me higher temperatures so an airtight chamber is like the requirement for a good insulation. On the other hand a real oven is blowing out hot air, too. It has to be like that because if not, you aren't able to blow hot air into the oven because of the air pressure.
    As I said my chamber isn't perfectly airtight at the moment. There are really small gaps somewhere. And I can feel the hot air is getting out there. So is this good or bad?
    The gaps are mainly at the side panels. Should I close them and install an exhaust fan at the very top? Then there is an air circulation from the chamber heater(s) at the bottom to the exhaust fan at the top.

    Or is it probably more effective to just close the gaps without installing an exhaust fan?

    Have you installed an exhaust fan @dvmourik ?

    PS: Why do my uploaded pictures have some funky purple strips at the bottom? Is this a bug?

  • @christoph13524 said in Pushing my heated chamber temperatures to the limit:

    On the other hand a real oven is blowing out hot air, too.

    I don't know about your oven... but for all the regular "kitchen ovens" I've ever seen the "hot air blowing out" is NOT from the oven cavity. It is from the layer that SURROUNDS the oven cavity, to keep the "outer" sheet metal cool enough for the whole oven assembly to be mounted in a wooden cabinet.

    The oven cavity itself, is semi-air-tight. Not super sealed... but no fans or intentional leaks either.

  • @christoph13524 adding to @Danal

    I would try

    • putting thin aluminium at the walls, so air warms up the aluminium, not the wood *)
    • isolate
    • restrict air circulation, so temparature exchange is low (like in a boiler, where you leyer temparature zones). So less fans
    • warm from the bottom, because heat climbs up

    In my understanding you will not need to heat the heat bed any more then or only at the beginning to equate it with the higher air temperature.

    *) I remember there is foil for human protection against undercooling. This could help reflect the heat.

  • @danal Thanks for pointing that out - makes sense. Then I will close the bigger gaps but won't install an exhaust fan.

    @JoergS5 Aren't aluminium sheets more against thermal radiation and not isolation?
    I thought about a better air circulation in the chamber to get a more even temperature. But first you need high temperature resistant fans and second I don't really need it anyway. My bottom temperature sensor gives me about 7 °C lower temperatures than the upper one. And that's ok for me. So there aren't any fans inside except the berd-air pump (is of course installed outside).

    I have just ordered a second 500 W heater. In combination with the foam all concerns should be cleared.

  • Can't wait to see if this actually improves your prints.

    1. You will want LOTS of airflow with ABS in a 90C chamber. Basically ABS in a 90C environment acts much like PLA in a 30C environment — low warp but needs some help cooling solid. Stratasys printers use giant fans to mix the chamber air and blast the print at nozzle height with hot chamber air. This is pretty much optimal. (Don’t pipe in cold air, blow 90C air.)
    2. If you use a radial blower type fan, you can install the fan OUTSIDE your heater chamber, to pull hot air from a hole in the side of the insulation and then duct it back above the build plate. Yeah, the fan will have 90C air inside it, but the outside will be cool, so a 70C rated fan should work. (I think.)
    3. Or you can just buy better fans. Here’s an 85C blower for $26. https://www.digikey.com/product-detail/en/BFB0712HHD77/603-2092-ND

  • I thought about an berd air cooling system. Sucking in the hot air from the chamber and blowing it out to cool the part. But I am not sure if the berd air pump is able to withstand 90C hot air. Although the pump is mounted outside. Depends on the plastic the pump is made from. Anyone knows that? The manufacturer couldn’t answer me how hot the sucked in air can be.

  • @christoph13524 said in Pushing my heated chamber temperatures to the limit:

    berd air pump

    You can 3d print your own like
    and take the filament you want, which is ok for your temparature.

  • Something like this with the motor located outside the heated area might do the job and do it quietly. It can definitely move more air than you will ever need.

  • @mrehorstdmd nice blog post on the fan! People really screw up axial fan implementation a lot. By the way, I tried to send you a Google Group private message recently, do you check that email address? Got something you might be interested in.

  • @mrehorstdmd The motor shouldn't be the problem, I think? It's more the plastic that gets soft and there aren't thermal data so I can't buy it..

  • After insulating the printer quite well plus adding a second 500 watt heater, I finally reached about 90°C in the chamber with the heated bed at 110°C.
    It takes about 30 min to reach 80°C and 1 hour for 90°C which is totally ok. It can't go higher anyway so the chamber heaters are always on.
    Also had to do many smaller adjustments like printing all plastic parts out of PC to make this possible.

    Now ABS and PC print basically like PLA. Zero warping - I love it.
    The water in the water-cooling-system only gets about 15°C warmer with all heaters on.


  • Your first post mentioned that your components were printed in Extrudr's GreenTec PRO for heat resistance. Was it necessary to replace them with PC?

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