OFFSET X from endstop



  • My endstop is pass the end of the table so I have a travel of 405 on my X axis.
    No I have a Titan Aero which eats up some space where the X and Y motors are at.
    I set my bed to X396 whiche is the space between the two motors so when I home and go to 0 it stops in the correct place on the left Y0 X0.
    now if I move back to X max it does not stopbefore the endstop but at the endstop so it hit the motor mount.
    I was reading about travel limits but can figure it out.
    The offset is to move the head +/- from the X0 Y0 (or at least in my tests).
    So after homing can you tell it that the like -4 from the endstop position of do I have to move my endstop.

    Still reading but if someone can help would be glad.
    Thanks



  • Just put your minimum travel limit as a negative number.

    Eg my corexy with titan x needs to start 10mm after the endstop so I use
    M208 X-10 S1
    M208 X270

    This sets min and max. It can home to the endstop but then it will say x=-10 on panel due or DWC. Since your slicer is never going to command a move to a negative x coordinate (unless its a delta printer) it will never move to hit the endstop.



  • Thanks Simion I think I did try that but not with the S1 and not the M208 X270.
    Will try when its finishing printing and let you know:

    Steve



  • The S1 denotes minimums.
    Without S1 it denotes maximums.
    X270 is my x max size on my corexy printer substitute yours.
    Your minimum will be different too.
    Sorry if this is obvious but I just want to be clear.



  • Yes I went and read the gcode and say that I did have the S1 in my somand line.

    I have a 42 x 42 (frame is 51 x 52) bed but the motor mounts etc limit the x moviment so I have to keep the area to X 399 x Y360
    so to have as much X as possible. Now I would like to limit X so I can gain some Y moviment say a 385 x 385.

    I been trying all evening but yet it still does not work.
    I set M208 X385 S1 (max) now when I do Home X and it hits thew end stop I get 385 in DWC as position X
    If I move it to the left -385 it stops where I what it to stop so as not to hit the motor mount.
    M208 X0 is minimum.
    Now if I move it back to X385 it will stop at the endstop and the right motor mount.

    Tried with M208 X XX if +/- it only effects the position on the left but not to the right and
    it will move always to the endtop and not stop using the value in M208 -10 (which would be 375 and it what I would like)

    So either Its not obvious to me or there is something missing 🙂 (which is possible as i have sleep in 2 days.)


  • administrators

    Are you saying that after homing X, you don't want to allow the head to move as far as the endstop any more? If so then you can use M208 commands in your homex.g and homeall.g files, to use one value during the G1 S1 homing move(s) and a lower value afterwards.

    IMO there is a lot to be said for setting the M208 commands so that X0 Y0 is the centre of the bed, and configuring the slicer to centre the bed on X0 Y0 too.



  • Yes thats correct David. On the M208 command in G Code RepRap there is very little info.
    So I would need to add the command in the homex.g after it does the homing command like below
    or in the config.g?

    I see that when you use the Home X in DWC its a G28 X

    in config.g I have
    M208 Y0 Z0 S1 ; set axis minima (adjust to make X=0 and Y=0 the edges of the bed)
    M208 Y360 Z400 S0 ; set axis maxima (adjust to suit your machine)
    M208 X-2 S1
    M208 X385

    in homex.g I have

    G91 ; relative positioning
    G1 Z5 F6000 ; lift Z relative to current position
    G1 S1 X410 F1800 ; move quickly to X axis endstop and stop there (first pass)
    G1 X-5 F6000 ; go back a few mm
    G1 S1 X410 F360 ; move slowly to X axis endstop once more (second pass)
    G1 Z-5 F6000 ; lower Z again
    G90 ; absolute positioning

    Thanks for any links to a more detailed use of M208



  • @DjDemonD:

    Just put your minimum travel limit as a negative number.

    Eg my corexy with titan x needs to start 10mm after the endstop so I use
    M208 X-10 S1
    M208 X270
    This sets min and max. It can home to the endstop but then it will say x=-10 on panel due or DWC. Since your slicer is never going to command a move to a negative x coordinate (unless its a delta printer) it will never move to hit the endstop.

    I must have something setup backwardsas this does not work for me.

    Where is your endstop on the right or left and where is your Y0 X0 right or left.
    When I home, if I have set M208 X385, in the DEC its say x position 385, now I move left to zero using M208 X-2 S1 as my limit so it stops befor hitting the motor mount.
    But if I move to the right, positive X, it will keep going until it hits the endstop say X 385 in the DWC.

    If i use any other number it will move left that amount so if I use M208 X 200 it will stop in the middle.


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