[kenthompson]

Hi all,

I'm hoping someone here might have insight—thank you in advance for taking a moment to read this.

I’m running into an issue with my legacy Model Master CNC (Model Master controller, Art2Part software) where the Z-axis only moves up, no matter the jog direction, and is now stuck at the upper limit. The limit light is stuck on.

This started about a month ago after a Z-axis stall in a similar manner. I removed the enclosure and rebooted—Z movement returned, but the limit light remained on. I used the machine that way for a couple of weeks without issue and then it sat unused for a few more weeks. When I powered it back on to try resolving the limit fault, I accidentally left it on for three days with the light still active. Now, five days later, when I attempted to jog the z axis down, it moved up. Jogging up also moved up. I didn't have much room to work with and now it is stuck back at the upper limit

I’ve done a full power cycle and tried booting with the Z DIN cable unplugged—no change. X and Y axes still jog normally.

Next steps I’m considering include opening the enclosure to inspect the limit switches (though they may be electromechanical and aren’t easily visible). A friend also suggested grounding the Z-limit pin on the 4-pin DIN to simulate a closed switch, but I’m hesitant to try without a schematic or input from others.

Would it make more sense to open the controller and inspect the board? Or possibly replace the controller altogether? I’ve looked into Centroid Acorn, Masso G3, and GRBL-based options but don’t know if they’re compatible with this system.

Any thoughts would be greatly appreciated—thanks again in advance!

[kenthompson]

I am using a Model Master 1000 with an NSK Astro 250. I am going to attempt to lower the Z axis manually before trying anything else.

If anyone has any advice otherwise I would appreciate it. Thanks!

P.S. I don't know why some of my images are being rotated.