I am trying to set up RepRap firmware for a CoreXY shown below. There are 4 limit switches in the top plane and one for the Z-axis.

I believe that LS1 & 2 are considered for the X-axis and LS3 & 4 are for the Y-axis. My question is do I need all of these switches? Is it even possible to program this many in the firmware?

Image of CoreXY indicating limit switches

  • $\begingroup$ Looks like they've got one for each axis at min and max. Not necessary. My CoreXY homes to Xmax / Ymin. $\endgroup$
    – towe
    Jun 17 at 4:39
  • $\begingroup$ I strongly recommend adding a second limit switch for Z, one per axis, so that you can level it via software. Also, it may be better to place the limit switch for Z at the bottom (Zmax), so that you never risk crashing the bed against the head $\endgroup$
    – FarO
    Jun 18 at 9:06
  • $\begingroup$ This is something I am trying to understand @FarO For CoreXY the head never moves downward like on a typical Cartesian. It is the print bed that moves. Right now I have a limit switch on the bottom of the Z axis and a BL touch at the top. I think it is not possible to put a limit switch at the top with this setup. $\endgroup$
    – Feynman137
    Jun 18 at 11:09
  • $\begingroup$ What you have is what I was recommending: in corexy Zmax is at the bottom $\endgroup$
    – FarO
    Jun 18 at 12:28

LS1 & 2 are considered for the X-axis

Yes, these correspond to X-max and X-min, respectfully.

LS3 & 4 are for the Y-axis

Yes, these correspond to Y-min and Y-max, respectfully.

do I need all of these switches?

Technically, no, you need one switch for each axis (if homing is used), but it can be saving your printer when somehow a layer shift has occurred which forces the head to move outside the bed dimensions.

Note that you even can use zero switches, but then you would need to position the print head yourself before each print and condition the G-code with a starting position, this is seen in some CNC machines.

It is a good idea to use min and max switches, but not necessary. (My CoreXY printer doesn't have the Y-max endstop as there was a little too less space to place it, restricting Y bed size...)

Is it even possible to program this many in the firmware?

Yes, firmwares allow for min and max switches, sometimes even multiple min or max switches for a single axis. The problem is whether your controller board has enough pins exposed and connectors added on the circuit board. But, min and max switches for X, Y and Z axis are not uncommon anymore, look at the specs of the controller board.


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