How to globally move a delta printer's print bed center position?



  • I feel like I'm missing something obvious and that there's an easy way to do this that I haven't found yet…

    I've got a delta with an effector fan shroud that interferes with a bed clip, so my allowable print area radius is smaller than it could be because of that one spot.
    I'd like to shift the whole print area in the -y direction in software. This lets me increase the effective print area radius.
    How can I do that and have it be in effect for all operations (such as bed calibration)?

    I've tried M206 Y10 and I've tried a Y move followed by a G92 Y0. Both appear to be intended only for cartesian use; the delta geometry calculations seem to get messed up after that.

    I've tried G10 P0 Y10 but that only changes the tool. Calibration is still centered on the geometric 0,0 (and would hit the clip if I increased the printable radius.

    And yes, I could fix this by changing hardware (not easily) but I'm hoping there's an easier way.

    Thanks for any pointers!


  • administrators

    That's a really interesting question. I know that's not the answer you would want…

    Alot of the delta calculations are based upon the symmetry of the delta design, with the tip of the hotend in the center. This is particularly true for calibration so for that you need to stick with the current radius from true 0,0.

    What is wrong with using the G10 X0 Y10? (calibration aside?) It is ok to calibrate on a smaller radius that you end up printing on.



  • @T3P3Tony:

    What is wrong with using the G10 X0 Y10? (calibration aside?) It is ok to calibrate on a smaller radius that you end up printing on.

    I was hoping that there'd be a simple gcode setting that would be global in effect. But yes, I now see that I could increase the printable radius, use the G10 adjustment, and tweak the probe points in bed.g and the mesh grid radius in config.g

    Thanks!



  • @swoozle:

    … I now see that I could increase the printable radius, use the G10 adjustment, and tweak the probe points in bed.g and the mesh grid radius in config.g

    This is what I do. I set up bed.g to the "whole" bed, then one by one, move the effector to each position in the bed.g file (starting at least +10Z to not hit clips, etc. If I'm going to hit a belt or clip, I just change the X and Y points in a few mm til I'm clear. Also - keep your dive height at 20 or so for the first time you do a G32 to make sure that you movements between points don't hit the clips.

    ( I want to move to the smaller "Swiss" clips, but I'd like to find them in the US to save on shipping. )

    John


  • administrators

    Both M206 Y10 and G10 P0 Y10 ought to work. G92 Y0 will not.



  • I have clips that could impact the fans on the X axis of my effector, so I just calibrate on a 10mm smaller radius (130mm) than the actual max radius of my setup (140mm). I have similarly limited my bed mesh.
    So long as I pay attention to never try and print at max values in X during the first 5mm or so I'm safe. A calibration done at a slightly smaller radius is unlikely to be appreciably less accurate than one right on the limit.



  • @dc42:

    Both M206 Y10 and G10 P0 Y10 ought to work. G92 Y0 will not.

    I appreciate the info from all, but David I think there are some issues with M206. I went back and played with M206 Y10 again and it does some wierd sh*t. It probably doesn't matter; I admit my need is an outlier. But, in case it is of interest:

    What I commanded (except for the initial M206, everything was done using "Head Movement" controls)

    • What the head did (also, the "Machine Status" display always matched the physical head location, not an axis shifted location)
      –--------
      M206 Y10
      Home all axes
    • head homes to Y= -10
      Jog down to z=0
    • head moves to y= -20 while moving down (!?)
      Jog Z+1
    • head moves up 1 and jumps to Y= -30 while doing so (!!??)
      Jog to max Y
    • Head moves to same physical y max as before the M206 (i.e. it doesn't really help me)
      Jog Y+1 a couple of times (beyond the bed radius)
    • the head jumps back y-10
      Jog down to y min and a little off of the X axis
    • normal movement
      Jog Y+1 repeatedly to get away from the bed radius limit
    • head moves in the X direction a little each time (!!??)

    And other (repeatable) bizarre behavior.
    But the bottom line is it doesn't move the axis globally. The head still obeys the M665 bed radius limit from the physical 0,0 center, not the axis-shifted center.
    Using absolute coordinate gcode moves does remove the strange jumping around but the head still will go where I don't want it to go and it adds the confusion of the status display coordinates no longer matching the gcode coordinates.

    Thanks!


 

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