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New Lead screw for Z axis

Mario WurzingerMario Wurzinger Posts: 12Member
in Modifications & Upgrades
Hi,

I got a new lead screw with 8mm lead. Now I did a change in Marlin at configuration.h
I changed the following --> #define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 400, 100 }. The 400 are the new value. Before it was 800.

Is this correct?

I got this screw: https://www.amazon.de/gp/product/B01LXHXUN1/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1
The quality is really amazing!

Thank you
Best Regards
Mario

Comments

  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited May 2019
    I think you're right. The old lead is 4mm, so that means half the rotation for the same lift. So half the steps for the same lift, so 400 looks good to me :smile:

    You can also set the steps per mm via gcode and save to eeprom:
    M92 Z400 ; set z steps
    M500 ; save eeprom
    Note, if you reset the eeprom in the future to defaults (M502 then M500) , the old settings will be loaded.

    Post edited by Samuel Pinches on
  • Mario WurzingerMario Wurzinger Posts: 12Member
    Hi Samuel,

    Thank you!
    I did a first test on this values. Does not seem to work properly.

    Do you know this calculator?
    https://blog.prusaprinters.org/calculator/

    Therefor I need the right values for "Motor step angle" and "Driver microstepping" which I dont know.

    Well, I will do some more tests on it.
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    Microstepping should be 1/16, and motor step angle I think is 1.8º. If you manually move up 10mm using the LCD, can you measure the actual movement? Then we can correct the Z step value.
  • Mario WurzingerMario Wurzinger Posts: 12Member
    edited May 2019
    If I move up about 10mm on LCD it is moving 19,96.
    But I already did a change in Marlin.
    Current value: #define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 100, 100 }

    The new lead screw also got 4 start points. Maybe this has also an effect.
    Post edited by Mario Wurzinger on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited May 2019
    If you flashed the firmware with the new values, try a eeprom reset to firmware defaults and then save eeprom to make sure those new values are applied:
    Send M502 then M500

    Post edited by Samuel Pinches on
  • Mario WurzingerMario Wurzinger Posts: 12Member
    Thanks a lot.

    The command M502 does solve the problem.

    BR
    Mario
  • coolt5coolt5 Posts: 38🌟 Super Member 🌟
    Mario Wurzinger 
    so how was the update from 4mm to 8mm 
    can you shear some info and your experience with the change in quality of print
  • Laser8302Laser8302 Posts: 170Member, 🌟 Super Member 🌟
    I would think you want to keep the 4mm rods for more resolution?

    4mm x 1.9º/step = 0.02mm per full step
    8mm x 1.9º/step = 0.04mm per full step

    I don't understand why you would want to change 4mm -> 8mm, I can understand 8mm -> 4mm though.
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