SOLVED Max Temp. of Heated Bed

Discussion in 'Calibration, Help, and Troubleshooting' started by Irawan Tri Kusumo, Jun 4, 2016.

  1. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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    I am sorry if this has been discussed. I am trying to print ColorFabb HT, but it needs at least 100 ºC for the heated bed. My Printer stuck at 97 ºC, and from 60 ºC above it is very slow increment. Does it normal ? What is the maximum temperature I could go with BB Heated Bed ?
     
    #1 Irawan Tri Kusumo, Jun 4, 2016
    Last edited: Jun 4, 2016
  2. Dr Jeep

    Dr Jeep Well-Known Member

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    it really depends on the room temp, the thermal losses are directionally proportional to the surface area of the heated plate and the temp difference between the plate and the air and airflow around it.

    In my workshop at 15c I just tested it and mine can get to 100 but it takes it about 35 minutes and I can see it levelling off on the temp graph to the point I'd say that it wouldn't go much higher unless I heated the workshop up a bit or put the printer in some sort of enclosure.

    What temp is the room the BB is in and are there any obvious drafts ?
     
  3. Dr Jeep

    Dr Jeep Well-Known Member

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    Another thing that helped on my previous printer was adding insulation under the bed. But if you are printing something that needs those sort of bed temps I'd be very wary of doing it in a cold room anyway as any draft will cause warping
     
  4. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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    It is in my office with Air Con is On, the Aircon is set to 20 ºC. I am printing now with ColorFbb HT, with the bed set to 97 ºC, but it is shown as 85ºC only (still printing), and I installed BuildTalk on the glass. Hope this will help a lot.

    IMG_0706.JPG
     
  5. Dr Jeep

    Dr Jeep Well-Known Member

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    Yeh never printed in a room with air con, it's not a general problem we'd have in the UK Can you protect the printer from drafts of air from your air con unit ?

    Also if it's not hitting that temp you could try popping off one of the heated bed connectors on the rumba and testing the heated bed resistance with the bed at room temp. some of them were out of spec early on in the KS project.
     
  6. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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    @Dr Jeep, thanks for the info. I can't protect the printer, but I did turn off the air con and the heated bed temperature increased by 4ºC. After finished printing I will put more isolation underneath the bed.

    How do you test the heated bed resistance ?
     
  7. Dr Jeep

    Dr Jeep Well-Known Member

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    If you have a multimeter to hand just unscrew the heated bed terminals from the Rumba board and put the meter (on the ohms range) between them when the bed is at room temp.
     
  8. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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    And what value of the resistance should be. Thank you, @Dr Jeep
     
  9. Dr Jeep

    Dr Jeep Well-Known Member

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    Dunno I'll tell you when my printer stops printing :)
     
  10. elmoret

    elmoret Administrator

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    Ideally 2.2 ohms, +/-0.3ohms.
     
  11. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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  12. R Design

    R Design Well-Known Member

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    If the resistance (and voltage!) is OK, there might be a case for PID tuning the bed?

    I remember doing a test run to 120C when the room temperature was circa 15C and, though it crept up slowly, the result was quite satisfactory.
     
  13. Dr Jeep

    Dr Jeep Well-Known Member

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    Maybe..I wouldn't have thought pid tuning would be the problem if it can't even get to the target temp. Worth doing though.
     
  14. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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  15. Alex9779

    Alex9779 Moderator
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    This are my values for hotends and bed:
    Code:
    // E3D v6 (PT100, 30W)
    #define  DEFAULT_Kp 24.00 // E3D 29.20
    #define  DEFAULT_Ki 01.80 // E3D 04.73
    #define  DEFAULT_Kd 79.10 // E3D 45.33
    
    //E3D BigBox Variable Power Density Heated Bed (24V)
    #define  DEFAULT_bedKp 170.70 // E3D 336
    #define  DEFAULT_bedKi 32.80 // E3D 61
    #define  DEFAULT_bedKd 222.50 // E3D 462.4
    
     
    #15 Alex9779, Jun 5, 2016
    Last edited: Jun 5, 2016
  16. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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    can't thank you enough @Alex9779 , you are so helpful and full of info... thanks a lot ..
    Hey, just saw that you are a staff Member ? E3D ?
     
  17. Alex9779

    Alex9779 Moderator
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    I am some kind of freelancer for E3D now...
     
  18. Dr Jeep

    Dr Jeep Well-Known Member

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    Those values are the default values in the firmware before tuning aren't they ? Mine came out a bit different when I actually tuned it.
     
  19. Alex9779

    Alex9779 Moderator
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    Crap you're right, I had the wrong branch active... edited my previous post...
     
  20. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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    I have run the PID Tuning for the heated bed, but alway got time out about above 70ºC it is said:
    "PID Autotune failed! timeout". Then the temperature was dropping down.

    Edit: I tried again and again, and always got time out. So, I tried: when it time out I run the same command again and again, and finally it reached 100ºC after 4 times re enter the GCode command . Can actually I did it ? The last value is:

    Recv: Kp: 84.76
    Recv: Ki: 2.62
    Recv: Kd: 685.36

    can I use it ? Anyone can help me please? @Greg Holloway
     
    #20 Irawan Tri Kusumo, Jun 6, 2016
    Last edited: Jun 6, 2016

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