All about endstops



  • So I'm setting up a corexy. I have 3 independent z motors. The problem is, when trying to home the z axis when it is all the way at the bottom it crashes the z axis into the frame. Is there a way to disable this in software? Alternately, I could add a Z Max endstop and have it use that to prevent it, correct?

    Next question is about y carriage endstops. I want my y carriage to be perfectly square to my x carriage. I know I can achieve this by tightening belts and such, but is there a way to add two endstops to the y carriage, one on either side? How would I set this up and what is the best way to go about it?

    Thanks for the help.



  • @surgikill Simply put, with just two motors you can't get 3 degrees of movements! For X/Y movements you have two motors that need to work in tandem to position the carriage. In order to square the gantry, you need two independent Y axis and a separate X axis, so 3 motors. CoreXY needs perfect mechanical alignment or, if possible, software compensation for the tilt, if it is a fixed value.

    RRF supports axis tilt compensation, but that is good in your case only if your structure is mechanically stable. If not, you need to get back to the drawing board and find solutions for making is stable enough!


  • administrators

    @surgikill said in All about endstops:

    So I'm setting up a corexy. I have 3 independent z motors. The problem is, when trying to home the z axis when it is all the way at the bottom it crashes the z axis into the frame. Is there a way to disable this in software?

    Yes, the standard homing files raise Z (in your case, lower the bed) by 5mm to prevent the nozzle scraping over the bed when homing X and Y; and lower Z again afterwards. You can edit the homing files to remove those commands. Or you can use M913 to reduce the Z motor currents while doing that, so that the crash will be gentle.

    Alternately, I could add a Z Max endstop and have it use that to prevent it, correct?

    Yes, and use G1 S1 Z5 command to lower the bed 5mm in the homing files instead of G1 S2 Z5. You may even be able to use stall detection as the max endstop.



  • @catalin_ro I understand that. I was more looking for a way to have one side hit the endstop and continue to crash into it while the other side continues to move until it hits the endstop. Short of that, what's a good way to ensure that the y carriage is perpendicular to the X? constrain it in one spot and tighten the belts accordingly? That's basically where my issue is. Loose belts and it's perpendicular, tight belts and it's off.



  • @dc42 Could I just have the bed home to the max endstop and then continue as usual using the ir probe as the min endstop and for bed tramming? So it would basically be Home Z_Max, Home Y_Min, Home X_Min, Home Z_Min.


  • administrators

    @surgikill said in All about endstops:

    @dc42 Could I just have the bed home to the max endstop and then continue as usual using the ir probe as the min endstop and for bed tramming? So it would basically be Home Z_Max, Home Y_Min, Home X_Min, Home Z_Min.

    Yes, you could do that.



  • @surgikill If it is off when you tighten the belts you might have a structure that is not rigid enough. Differently said, you over-tighten the belts for the rigidity of your structure. Or there is a slight design flaw with your mechanical solution. Can you share with us a photo of the belts placement, including steppers and all pulleys?


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