Hi, This might be the wrong section, or even the wrong forum. Hopefully I'm in the right place. I'm building my very first laser engraver. I'm at the point where everything's designed and being assembled, and many of the things I thought would be difficult ended up being very straightforward. But what the heck is the deal with limit switches? The switches seem to work fine in isolation, but whenever I perform a homing sequence with things wired up in the way I feels make sense, this is what happens: - X axis moves to limit switch while Y axis is completely stationary. - As the X limit is triggered, both X and Y axis moves away (pulloff distance), and a homing error is thrown. However, depending on which limit switches are plugged in, this behaviour changes: - If only the X limit switch is connected, the Y axis will attempt to home in the reverse direction, opposite of home. - If only the Y limit switch is connected, the X axis will attempt to home. If I change which wires of the limit switches are hooked to the board (switches are 3-pin, board only has space for 2 pins), the behaviour changes again. Instead of RED/BLACK wires, let's try BLACK/WHITE wires. X+Y limit switches connected: - Only Y homes in reverse. X is stationary. Flipping $23 (homing direction invert) has no impact. Y still homes in reverse. X limit switch connected: - Only Y homes in reverse. X is stationary. Flipping $23 (homing direction invert) has no impact. Y still homes in reverse. Y limit switch connected: - X homes in the correct direction, while Y homes in the reverse direction. Flipping $23 (homing direction invert) causes X to also home in the reverse direction. What can I do to troubleshoot and fix my setup? I've been Googling quite a bit, but I'm just not sure where to even begin. I might be doing something OBVIOUSLY wrong, and maybe you know exactly what it is. Relevant HW info: I have a Dinqi Electronics board scavenged from a friend's terrible CNC machine. It is flashed to GRBL 1.1 via LaserGRBL (XYY setup) These are the limit switches: 5Pcs Horizontal Type Mechanical Endstop Switch with 1m Cable for 3D Printer Reprap Ramps1.4 Attached is some photos of the setup.
before homing (turn it off in the grbl settings) you must make sure the X and Y motions are in the correct directions. You do this by using the jog buttons, X+ must move the head (the tool) to the right Y+ must move the head away form the front of the machine. Those switches need 3 connections, ground, power and signal, since they have active circuitry on the little board, looks like an LED comes on when the switch is hit. The limit switches should be at the + ends of the axes, otherwise this is much harder to set up. Clear the limit switch invert if it is not zero $5 - limits invert Grbl v1.1 Configuration · gnea/grbl Wiki Clear the limit direction invert too. Activate homing Now, with your hand hovering over the emergency stop/power switch, start a homing cycle. X and Y should move (+ direction) at the same time till they hit the switches, then withdraw and then individually re-hit the switch, then withdraw by the $27 value which must be far enough to fully release the switches. IF one or both of them move in the wrong direction, hit the power off, swap the homing direction($23) (not the normal direction) then reset the controller and try again. If you choose to put the switches at the other ends, then you will have to read that whole Wiki to figure out the settings you need. All CNC machines home at the positive ends of travel, an industry standard, no surprise movements.
Also, if you don't have a Z axis, you must first recompile Grbl to disable the Z axis Homing (which happens first) - i only see two switches. This is discussed on the Grbl Wiki > FAQ Page
