Grinding during homing

When I initialize the cnc, it struggles with z and grinds away for a few seconds before finding the homing switch. It also does this (though less frequently) with the other switches. Sometimes it keeps grinding and i have to turn it off and on again. I also lose z during a carve occasionally and it goes too deep and ruins my piece. Anyone else experienced this and have any ideas? Here is a quick video of the issue. Wasn’t too bad this time. Usually it’s a little worse.

That sounds like belt slipping on the z axis stepper motor pulley, but not likely a loose belt, more like a dodgy z homing switch. Check all of your board connections for the limit switches, you can press each with the machine on and see the corresponding blue lights in the board light up. Also check to make sure they are all making contact and getting depressed at their limits. Depending on how many times it’s cycled like that you may have also eaten up the belt a little where it passes over the motor pulley. Check that and replace as needed, short term you might be able to reclock the belt to a fresh set of teeth.



Thanks Dan. Looking for 5 to 8 inches of snow this weekend so lots of time to do maintenance lol.

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Took the router out (dewalt died so had to anyway so I could take it to service center) and reworked the belt. It looked fine but who knows. Cleaned all the vwheels, checked for any damage, made sure all connections were tight. Haven’t done the limit switch test yet but tried initializing after reassembling and no grinding this time. Only tried once as I got sucked into something else but at least it was a good start.

Thanks again Dano.

Good the belts not torn up, that’s really the only thing I can see getting torn up, albeit it sounds pretty awful. It sounds/appeared to me watching the video that either the homing switch is intermittent or not hitting and fully being pressed. Intermittent could be bad switch, bad wiring, bad plug/loose connection. If it’s being pressed good mechanically the first place I’d check is the plugs and the blue light test…oh yea, safety disclaimer…don’t mess with the wiring with it powered up, it’s never good to see the “Smoke Spirit” leaving your electronics!


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I try not to mess with wiring too much anyway, I have a lot of Tim “The Toolman” Taylor in me.

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whats the temp in the room?

It’s an insulated garage, so depends on what the temp is outside. Lately it runs about 40 to 45 degrees on average, but has been low 30’s at some points.

Right after putting everything back together, the grinding stopped completely and things were looking great…and then my DeWalt died. Hoped it was the brushes, but they were fine (replaced with new to make sure), so she is at the emergency room, otherwise known as the service center. Dead in the water until I get it back. They said 3 weeks so I hope they stick to that.

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