Removal of support for 3-, 4- and 5-point G32 bed compensation


  • administrators

    Currently, RepRapFirmware supports two types of bed compensation:

    • Mesh bed compensation (G29)
    • Legacy 3-, 4- and 5-point bed compensation using G32 and a bed.g file.

    I propose to remove support for legacy G32 bed compensation in a future firmware release. The G32 command and bed.g file would then be used exclusively for the following functions:

    • Auto calibration of delta printers, and perhaps other printer architectures in future
    • Bed levelling using multiple independent Z leadscrews
    • Bed levelling using manual bed levelling screws

    The only command for probing to do bed compensation would be G29. Those currently using legacy 4-point bed compensation could switch to 2x2 G29 mesh bed compensation, provided the probing points are arranged in a square and no trigger height corrections are needed (H parameter in the G30 commands). Those using 5-point compensation could switch to a 3x3 G29 mesh, again assuming that no trigger height corrections are needed.

    Are there any users reading this using legacy G32 bed compensation, who would not be able to change to G29 mesh bed compensation?



  • I'm good with that.



  • Makes sense to me. There is less room for confusion if there is one way and one way only to perform each task.

    Frederick



  • I think that most people currently setting up G32 and a bed.g file are only doing it because that's the only way they're familiar with even though G29 does what they want and more. Then they end up trying to use both which doesn't work.

    Woukd G32 be completely depricated? Or would it still call bed.g? It's a rather large change that people will obviously find annoying. But such is the way of progress. 😉



  • I use g32 only for the purposed functions (dual lead screws alignment and manual bed leveling) so it is ok for me.



  • How do you do the physical bed levelling without G32 & bedg.g? I seem to remember that automatic correction of a three motor z-axis relied on probe points as close as possible to the screws?

    Please can this be updated to explain how to do it without G32 and bed.g:

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



  • @doctrucker said in Removal of support for 3-, 4- and 5-point G32 bed compensation:

    How do you do the physical bed levelling without G32 & bedg.g? I seem to remember that automatic correction of a three motor z-axis relied on probe points as close as possible to the screws?

    Please can this be updated to explain how to do it without G32 and bed.g:

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

    As far as I understand, G32 will still be there for use with bed.g, but only for use with Physcial bed leveling just like you ask. He want's to remove some old leagacy bed compensation from G32 (which is also in G29)

    For a guide how to use G32 with 3 lead screws, see the last part of this: https://betrue3d.dk/bltouch-on-duet-wifi-configuratio-and-usage/



  • @martin1454 Yes, miss read of the original post by me. Thanks.



  • Please don't do this! I currently built a big update on my cartesian and corexy to calibrate my 2 leadscrews before running a G29. (and also some users in the german Facebook group are going to rebuild it) https://www.thingiverse.com/thing:3181212
    The G32 command is perfect! Don't want to miss it



  • @kuhnikuehnast
    this will still work:
    "............
    Bed levelling using multiple independent Z leadscrews
    Bed levelling using manual bed levelling screws
    .................."



  • good idea, the whole concept with borh G32 and G29 was a bit confusing


  • administrators

    One additional item that will still be supported is using bed.g to test Z probe repeatability, using a series of G30 commands with a S-1 parameter on the last one.



  • As it stands, the proposed functions are exactly what I use G32 for, ie: adjusting multiple Z lead screws.

    Z probe testing is something that I should probably do, too.



  • I'm currently modifying my printing gcode for a 3x3 grid before printing (used to do a g32 5 point + a large occasional g29 20x20 point it adapts to, I'm finally taking the time to fully understand g29)

    if I manually keep a grid of 20 x 20 for minor curves in my bed, then use a 3x3 grid each print, will the g29 printing gcode keep the 20x20 grid and be adjusted by the 3x3 grid or will the printer only print using the new grid?

    I have already set up my g29 parameters for the 20 x 20 grid, so adjusting for a quick 2x2 or most likely a 3x3 after bed heating isn't an issue, it's mostly if the 20x20 grid can still be used, I don't want to spend an hour probing for each print, but the 20x20 grid allows for really nice first layers on a metal bed.

    current bed leveling gcode,
    ; bed.g
    ; called to perform automatic bed compensation via G32

    M561 ; clear any bed transform
    M400 ; dummy for Z probe, stop any moves
    G28 ; home all axes
    ; Probe the bed at 5 points (removed for now, only g29 is loaded)
    ; G30 P0 X26 Y3 H0 Z-99999
    ; G30 P1 X26 Y300 H0 Z-99999
    ; G30 P2 X263 Y300 H0 Z-99999
    ; G30 P3 X263 Y3 H0 Z-99999
    ; G30 P4 X144.5 Y155 H0 Z-99999 S5
    M400 ; dummy for Z probe, stop any moves
    G29 S1 ; load hight map (needs to switch to a csv file)
    M376 H10 ;taper the compensation after 10mm

    printing gcode needs to switch g32 for a g29 loading then 3x3 probing, and a macro for 20x20 probing to a csv needs to be copied/ made.


  • administrators

    @sheldor said in Removal of support for 3-, 4- and 5-point G32 bed compensation:

    if I manually keep a grid of 20 x 20 for minor curves in my bed, then use a 3x3 grid each print, will the g29 printing gcode keep the 20x20 grid and be adjusted by the 3x3 grid or will the printer only print using the new grid?

    No. You can only have one type of bed compensation in effect at a time (either the old 3/4/5-point bed compensation, or mesh bed compensation), and if you are using mesh bed compensation, only one grid can be active at a time.



  • @dc42 darn, looks like I'll have to do something like 4x4



  • @Sheldor Is it really necessary to do a multipoint probe before each print? You can load the detailed heightmap and as long a your bed hadn't gone out of level or shifted it did still be relevant.



  • @phaedrux said in Removal of support for 3-, 4- and 5-point G32 bed compensation:

    Is it really necessary to do a multipoint probe before each print? You can load the detailed height map and as long a your bed hadn't gone out of level or shifted it did still be relevant.

    I have not found it necessary to probe before each print.

    On my FT-5 I don't have a probe and just check the bed manually using a shim gauge once a month or so but it doesn't seem to be changing.


  • administrators

    @fcwilt said in Removal of support for 3-, 4- and 5-point G32 bed compensation:

    On my FT-5 I don't have a probe and just check the bed manually using a shim gauge once a month or so but it doesn't seem to be changing.

    If you have a good Z probe, you can use it to check the bed level and tell you the levelling screw corrections needed. See https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant.



  • @dc42 said in Removal of support for 3-, 4- and 5-point G32 bed compensation:

    If you have a good Z probe, you can use it to check the bed level and tell you the levelling screw corrections needed. See https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant.

    Someday I'm going to fit a Z probe and try that out.

    It takes just a few minutes to adjust the leveling screws manually using the shim gauge and the results are all I could ask for. The printer works great.

    Thanks for the reminder.


Log in to reply