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Turn Version 1 Bed Heater into a Version 2 Bed Heater

Discussion in 'Mods and Upgrades' started by WheresWaldo, Jan 11, 2018 at 10:24 AM.

  1. WheresWaldo

    WheresWaldo ✌(◕‿-)✌
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    Since I had my bed replaced with a version 2 I had the original bed to play around with. Since the version 2 bed requires the removal of the Pogo Adapter, that was no longer in the way. The biggest obstacle was finding the appropriate connector to make an adapter cable to connect the old bed to the wiring harness. What I found was that the connector used was a Chinese clone of the AMP TE 5-103945-7, which is a crimp male socket for the wiring harness connector. The connector is wired as follows (from left to right looking down at the keyway)"

    1. Thermistor
    2. Thermistor
    3. Bed +
    4. Bed +
    5. Bed +
    6. Bed -
    7. Bed -
    8. Bed -
    A bit of heatshrink and Kapton tape and now I have a working version 2 bed.

    20180111_124610[1].jpg

    20180111_124553[1].jpg
     
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  2. WheresWaldo

    WheresWaldo ✌(◕‿-)✌
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    I should note that both the bed and the thermistor are purely resistive loads so you do not have to worry about which side is positive and which side is negative when you attach the cable.

    The AMP connector is rather small and will only accept wiring up to 20 AWG. That is why the heater is wired with three wires per side, The Robo wiring harness also uses 20 AWG wiring.
     
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  3. WheresWaldo

    WheresWaldo ✌(◕‿-)✌
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    The white sheet is PEI but I would not recommend using it. So far in my testing the trigger distance is increased almost 10 mm higher than the black. I find that the trigger point is between 12 - 14 mm from the bed. Of course you can handle that with Home Offsets but I also tested the repeatability of the probe with the white sheet and what I am seeing is a range of trigger points that is almost on the verge of unacceptable. I ran the command M48 P10 several times to that I could get a range of 10 measurements. All measurements were taken at the same location on the bed to reduce any variables. Here are the results

    Run 1 - Mean: -0.379250, Min: -0.536, Max: -0.291, Range: 0.245, Standard Deviation: 0.068309
    Run 2 - Mean: -0.406325, Min: -0.503, Max: -0.291, Range: 0.212, Standard Deviation: 0.071752
    Run 3 - Mean: -0.389225, Min: -0.522, Max: -0.244, Range: 0.278, Standard Deviation: 0.087773​

    What is disturbing is the range that the probe finds acceptable. I will retest with the standard Robo bed and provide those results as well.
     
  4. WheresWaldo

    WheresWaldo ✌(◕‿-)✌
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    Just for a point of reference, I performed the same test on the Robo BuildTak sheet used in bed version 2. Here are the results using the same command, and probing in the same location:

    Run 1 - Mean: -0.038700, Min: -0.090, Max: 0.028, Range: 0.118, Standard Deviation: 0.035226
    Run 2 - Mean: -0.070875, Min: -0.104, Max: -0.022, Range: 0.082, Standard Deviation: 0.027702
    Run 3 - Mean: -0.055000, Min: -0.099, Max: -0.014, Range: 0.085, Standard Deviation: 0.023808​

    Of course this is just one data point, but it is apparent to me that using the black sheet not only lowers the trigger distance but also makes it more repeatable.
     
  5. JeffreyB

    JeffreyB Member

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    Did you see this? Are they actively working on the IR's lack of accuracy due to varying ambient lighting? https://github.com/Robo3D/Marlin/blob/DAC_Edit/README.md

    • Added G35 command. Auto adjust Probe Offset(M851 Z) for ambient light levels based on the trigger distance of the IR probe(Requires Home Offset Z(M206 Z) to be set)"
     
  6. WheresWaldo

    WheresWaldo ✌(◕‿-)✌
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    Yes I saw it and it is not a solution. All that code does is force resetting the home offset for every print if you use that particular non-standard g-code in your start up. It doesn't actually address the inconsistency in the probe.

    Please do not get me started on the code Robo produces. So far as long as I have watched their GITHUB they have not produced a single line of code that actually improves print quality or printer speed. They tend to ignore bugs in their code. They have no real means of accepting feedback or bug reports.
     
  7. mark tomlinson

    mark tomlinson ¯\_(⊙︿⊙)_/¯
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    The correct way of doing this would be for them to become actual contributors to the Marlin code and adding fixes/improvements to the main Marlin code-line. Forking your own path is certainly one approach, but does nothing to improve the actual main code (which presumably you would want to consume later for further improvements/fixes)
     
  8. WheresWaldo

    WheresWaldo ✌(◕‿-)✌
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    I have no issues with forking the code, but if you are going to add whole new sections of code, you should at least make sure it does something good. Just doing no bad is not enough.
     
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  9. mark tomlinson

    mark tomlinson ¯\_(⊙︿⊙)_/¯
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    Well, that would be a start ;)
     
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