How to make different bed probing patterns



  • Hey
    I am currently working on my project for my bachelors degree and I am due to quarantine unable to test whether my G-code works.

    Background:
    I am making a cartesian printer for bioprinting similar to this: https://all3dp.com/2/what-is-3d-bioprinting-simply-explained/

    I have mounted a FSR on top of the syringe, so that when the needle touches the bed, it will get squeezed and register and can therefor be used for bed probing. The Z-endstop is at the top, so it will only be used for bed probing. The trigger height will be measured once I am allowed access to my university.

    The bed is designed to attach either a petridish or different sizes multiwells: https://www.sigmaaldrich.com/catalog/product/sigma/m8562?lang=en&region=DK&gclid=CjwKCAiA17P9BRB2EiwAMvwNyHDWWf2rC0ZpnNOAkNs0A3OEAbc-PecdWQ6XL4AD6bRXAWmXKzU44hoCC8oQAvD_BwE.

    Depending on whether a petridish or multiwell (and what size) is mounted, I want to be able to choose different bed probings.

    Multiwell bed probing
    For the multiwell I have the current setup in the G-code:
    ---In the config.g file---
    M558 P8 C"!^zprobe.in" I1 H30 F50 T200 -; Defining type and speeds + dive height
    G31 P500 X0 Y0 Z-3--------------------------------; Guessing trigger height (for now)
    M557 X50:80 Y50:80 S15------------------------ ; Arbitrary grid for some multiwell

    ---In bed.g fil--- (run by G32)
    G28-------------------------------------------------; Homing
    G30 X62.6 Y41----------------------------------; Single probe in an arbitrary hole for Z=trigger height datum
    G29-------------------------------------------------; Probing and mesh bed compensation

    Questions for multiwell
    1.1: Does this method work in general?
    1.2: I have set the dive height to 30 mm. Does it mean that it will raise 30 mm between every probe? I have to make sure it clears the edge of the multiwell between each probe point because it will make a probe in each hole.

    Questions for petri dish
    I want to make probing at the radius. I just cant figure out how to do this properly and in which files to put the different commands. I was thinking about just making a macro file including all the commands, but I am not sure which ones to use.

    2.1: Can I somehow use the M557 R-command to probe in a radius around the middle of the petri dish (middle is placed at X62.6 Y41) and use G29 to execute it?
    2.2: If not, can I use M557 P to define a series of points to probe at? And can G29 be used afterwards to execute the probing and enable bed compensation?

    Thanks in advance!


  • Moderator

    @Frederik561 said in How to make different bed probing patterns:

    I have set the dive height to 30 mm. Does it mean that it will raise 30 mm between every probe?

    Yes.

    @Frederik561 said in How to make different bed probing patterns:

    Can I somehow use the M557 R-command to probe in a radius around the middle of the petri dish (middle is placed at X62.6 Y41) and use G29 to execute it?

    Yes. That's how it works. https://duet3d.dozuki.com/Wiki/Gcode#Section_M557_Set_Z_probe_point_or_define_probing_grid

    Does that get you what you need?



  • @Phaedrux Thank you for answering! About the probe in a radius, how do I define the point around which the radius is taken (the center)?


  • Moderator

    Typically the radius method would be used in a delta printer where the bed shape is round and the 0,0 origin point is the center of the bed. So it may make sense in your case to use a center origin as well.

    https://duet3d.dozuki.com/Wiki/Centering_the_bed_or_setting_the_bed_origin


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