Not homing as expected

Mostly Printed CNC - MPCNC Troubleshooting
1

Primo using a SKR Pro 1.2 with dual end stops…

I tried homing to hear the motors try to continue past the end stops. I do have a backwards setup machine due to the tool holder apparently not being designed for the Primo however the cut area I loose is negligible so I just decided to try and make it work.

My question is 2 fold.

  1. Why are the end stops not working even if the machine is not homing in the direction it expects to.
  2. What changes do I need to make to the firmware so the homing is reversed?

Thank you!

IMG_2996
IMG_29961920×2560 354 KB

2

You have to have a “right handed coordinate” system. You need somewhere you can stand where:

+X goes to the right
+Y goes away
+Z goes up

If that isn’t true, then homing will be funky and programs from your CAM will be flipped.

The endstops need to be on the lower limits of X and Y.

Other non obvious things:

Endstops won’t do anything unless homing. They won’t stop the machine when jogging.

Sending M119 will show you the state of the endstops without having to home.

If you have X1 and X2 swapped, then the homing will crash, because it will be stopping the wrong motor. Same with Y.

You will get there. It is close.

3

Thanks for trying to help. Not sure why end stops would not stop the machine when jogging but I am still looking for info on how to setup the firmware for a “right handed coordinate” system.

4

It’s strange this has not come up in the forum before since mounts that check all the boxes are a bit difficult to find. I know there are settings in marlin that will fix my problem however I have been unable to figure it out.

5

Because it’s running on 3d printer firmware, they only look at the stops on homing moves. After that they assume the gcode won’t go into the negative X and Y.

1 Like
6

I would argue also that you don’t want a false alarm endstop to ruin a job.

The machine can’t really hurt itself (but it is unpleasant to hear it slipping steps).

We also want someone to be able to use the preconfigured firmware without endstops and then add them later, if they like. They are triggered when they are missing, so that wouldn’t work.