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strange interaction between x/y and z steppers

Discussion in 'General Questions' started by John Pearsley, Jun 16, 2020.

  1. John Pearsley

    John Pearsley New Member

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    I'm trying to replace the R2 mainboard with a ramps/mega 2560 board pair. I have all 3 steppers connected to the ramps board with their end stops. I'm testing using the pronterface ui. When I first connect to the board and drive either the x or y stepper, only the Z motor moves for a short distance, it stops, then the respective X or Y stepper works correctly. I'm have been working with customizing the arduino code to work with the original R2 hardware using the new mega 2560 card. I've become fairly familiar with the arduino code and do not see anything in the code that would explain the behavior.
    Right now everything is removed from the printer and connected on my work bench which might be related to this problem but since the steppers work with both pronterface and pronsole programs ???
    Has anyone seen this behavior elsewhere? Any thoughts? Thanks guys.
     
  2. tkoco

    tkoco - -.- --- -.-. ---
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    Ask @Lance Weston . He has done a lot of work with the mainboard replacement and might be able to answer your question.
     
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Maybe try it from a GCode terminal directly if you haven't already.
    Assuming that doesn't help, try a different RAMPS.
     
  4. John Pearsley

    John Pearsley New Member

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    I think I figured this one out. It looks like the Z movement was from the G28 attempting to home all the axis. I think it was being sent before any other instructions. I think we can close this thread if that is the normal process.
     
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  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    G28 should be nearly the first command you send because others (like G29) will not work until after the G28 is done.
    However the slicer generally controls that (with any additional settings you have configured)
     
  6. tkoco

    tkoco - -.- --- -.-. ---
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    Agreed. For a G28 Homing G-code on the R2: Z axis first; followed by X+Y with a final stop check of X axis first and then the Y axis.
     
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  7. Lance Weston

    Lance Weston Active Member

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    My GCODE script issues G21, then G28 and homes all axis with no problem

    This is working code
    https://drive.google.com/file/d/1pHhWV9aA29iayfuwKz73C2HIgf1s32xd/view?usp=sharing

    Attached is schematic. The ports have to reassigned. Make sure you remove D1 or you will fry the CPU. This uses 12v to the fans and 24v to heater and bed. Remember to go to the terminal and run M502( load the constants) then M502 ( store the constants into eeprom)

    On the Ramps board I have found the heatsinks can short components with vibration from the printer. I believe it was the cause of some odd problems I had. What I do now, is: take to220 mica insulators and glue them to the bottom of cleaned heatsinks. I wait for it to dry then trim the mica insulators with a pair of cutters leaving about 1/16" all around. I then glue to the chips with no worry of shorts. You can find heat sink paste (glue) on eBay.

    Better yet contact Jonah@Partsbuilt.com. He has working replacement boards and might be willing to part with one before the final production boards come in.
     

    Attached Files:

    #7 Lance Weston, Jun 17, 2020
    Last edited: Jun 17, 2020
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  8. John Pearsley

    John Pearsley New Member

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    Lance
    At this point I'm still trying to test the new parts and settings. I've been using pronsole.exe and debug statements to follow the software.
    Thank you for your feedback. During these lockdown days, this project is keeping my busy and happy. Except for the problems :)
    J
     
  9. Lance Weston

    Lance Weston Active Member

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    About 10% of the CPU boards have flakies. I had one board that would randomly stop, sometimes it to 20 hours. I have another board where the Z sometimes returns to different locations. Really hard on my glass bed. I keep a large number of spares, and MOSTLY everything works first time out. I have not found any manufacturer better than any other. The cheapest source is Zyltech.com.
     

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