CoreXY moved endstops 24.5mm on X and Y Min endstop bounce and Jitter

Just installed a new J end mount for My e3d hot end this cause a bit of an issue as the new part cooling blowers are almost an inch in front of the end stops (i.e. never gets close) Moved X and Y end stops farther out by 24.5mm back and over (left side and rear) normally homing is XYZ on this CoreXY 

Now when I manually Home X or Y it comes up to the end stop and bounces, then jitters 

if I move manually before power on set the carriage into the x and y stop are on and lighted home and it goes up to Z end stop 

if I move, say 190 X and Y and 100 down on Z and if I choose to go home it goes to the end stop Y and then X jitters from left end (hard to tell if it actually get to Y but X moves right instead of left (end stop to about 100 and jitters never goes left to the X end stop, forcing me to do a hard power off 

 I checked the end stop with m119 all low and go high when Held, so the end stops work and the motors X and Y move when commanded with g1 x 190 Etc. 

Wondering if there is something simple I missed when moving to the new  end stop. Are they not static position? Do I need home X and Y manually and save the new home positions?  (acts like it wants to go farther than the end stop? since the new zero is 24.5mm away for x and y)

 Nothing has been touched in the Config file, only moved physically the X & Y end stops 24.5mm,  very strange. Any help or suggestions are welcome. Certain I am over thinking something?

Repetier 0,92 CoreXY 600x600x900 3 z motors I X 1 Y and 6 extruders ramps 1.4 (Soon changing MKS L version 2) 

this had been working now for 5 years until this endstop changes.


  • Not sure what you mean with "and then jitters". For core xy it is important that you move back from end stop when hit, so it does not trigger the end stop any more. Since x and y motor are used same time for x and y moves it is problematic. So maybe due to change one end stop does not fully untrigger and gets hit from time to time when moving y with x close end stop.
  • edited September 2022
    jitters basically it just bounces in one spot stops moving but is trying to move. 

    went back and pulled the X & Y reprap switches , at first i thought i had a corrosion problem was just very dirty and found the copper exsposéd the other one looked OK replaced the switches

    Installed a new optical sensor For the Y axis, Attached a target to the carriage rather then having it hit a switch, The new optical switch is a open is high  / Low signal 
    The X axis is same reprap end stop with Led as before., added a target to the carrier since they don't align.

    Looking at Y axis with a new optical style sensor (open is High and Closed is Low) 
    need to reverse, at Configuration h 
    endstop pullup_y min true
    endstop Y_min_inverting true (change this to false?) In my case for the COrexy 
    minhardware _endstop_y true 

    this was the only change for the one Optical sensor, been a while since i had to update anything in the Configuration files. Ran complier then upload ran the home button, smooth and silky no more bounce or jitters, guess the dirty switch was the issue 

    I only use the endstop min for XYZ 
    and  only other endstop max is  Z stop Max way down at 690mm just in case something goes very wrong 
    thanks you 


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