Grid levelling status



  • @terabyte:

    I think this feature differentiates the good firmware from the best. I can't wait to see if it works. While I am waiting for the grid compensation, what is the good source for flat beds?

    A good material for a flat bed is Cast Aluminium tool plate in the UK I get it from Aluminium warehouse http://www.aluminiumwarehouse.co.uk/cutting_calc.php it is there ECOCAST plate. and isn't to expensive.

    I generally use 6mm thick plate which for a 200mm square is approx £10 plus carriage

    HTH

    Doug



  • @dc42:

    @Adamfilip:

    How does the 5 Point leveling compare to (10x10)Grid leveling.. sounds like a simpler version of the same thing.

    It is.

    3-point levelling can cope with a bed that is flat but not level (tilted in 2 directions).

    4-point levelling can cope with a bed that is flat but not level, and additionally a twist in one axis that causes the bed tilt to vary uniformly with X and/or Y position. Or a bed that would be flat except that it has a uniform twist in it.

    5-point levelling is designed to handle a bed that is basically flat but has a uniform bulge or depression. centred on the centre of the bed. Or more commonly, the bed is flat but the print head dips slightly near bed centre because of bending in the gantry that carries the print head.

    The primary purpose of grid-based levelling as I see it is to compensate for beds that are not flat.

    D.C. So should Auto bed compensation run from DWC work with 3 points or are we talking about something completely different?


  • administrators

    Yes, you can define 3, 4 or 5 points in bed.g.



  • @dc42:

    Yes, you can define 3, 4 or 5 points in bed.g.

    David,

    That's what I thought but when I run it, the values aren't reported by DWC. To be clear, the points are front left, centre rear, front right in a clockwise direction. These get probed as expected but I don't get the normal "Bed Equation fits points….etc" that I do when I run 4 point compensation. There is nothing reported in the G-code console.

    Ian


  • administrators

    Try rear left, rear right, front centre. Make sure the probe points are numbered P0, P1, P2 in that order I tried that a long time ago and it worked for me.



  • Tried that - no joy

    Added a G4 just because my old RRP Mendel had one. Still no joy.

    Here is the file…..............

    ; bed.g
    ; called to perform automatic bed compensation via G32
    ;
    ; generated by RepRapFirmware Configuration Tool on Fri Sep 09 2016 09:45:21 GMT+0100 (GMT Standard Time)

    ; Clear any bed transform
    M561

    ; Probe the bed at 3 points
    G30 P0 X10 Y320 H0 Z-99999
    G30 P1 X315 Y320 H0 Z-99999
    G30 P2 X162 Y10 H0 Z-99999

    G4 P1500 ; give the interface time to report

    G1 X165 Y165 F6000 ; move to more or less the centre of the bed

    .........end of file

    It probes the bed in the correct order but doesn't report any equation.

    I'd rather use front left, centre rear, front right because they are the positions of my 3 screws so, (if it worked) the reported bed equation points would indicate which one I need to adjust.


  • administrators

    OK I'll re-test it when I get a chance.



  • Thanks DC. It's no big deal so it can go towards the bottom of your list.



  • You are missing the S on the last probe line.

    It needs to be:

    ; Clear any bed transform
    M561

    ; Probe the bed at 3 points
    G30 P0 X10 Y320 H0 Z-99999
    G30 P1 X315 Y320 H0 Z-99999
    G30 P2 X162 Y10 H0 Z-99999 S

    G4 P1500 ; give the interface time to report

    G1 X165 Y165 F6000 ; move to more or less the centre of the bed



  • Damn me, so I am. Well spotted sir! Fat fingers strike again. Don't know how I managed to delete that last S but I've put it right and can confirm that everything works as it should.



  • Just wanted to add that this a brilliant tool to use for initially getting the bed level if you have a 3 point levelling system. Just set the probe points as close as you can to where the levelling screws are and run the check. Leave one screw alone and adjust the others until the readings are as close as you can get it. I found it much easier than messing around with bits of paper or drill bits. Once set, you can always go back to 4 or 5 or more points is you want to.


 

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