Black powder along gantry rack and no jog

Hello all, new guy back again! First, thank you to everyone who has helped already, I would have given up by now without this forum.
The latest head scratcher has bee the cnc suddenly stopped responding to jog commands of any kind. The machine homed, then stopped altogether. Now, it will not respond to the keyboard, or anything in Mach 4 except the spindle start.
As I was looking into the problem, I happened to notice there was a powdery black residue along the top of the gantry, just in front of the X-Y axis rack.
Soo… just how badly did I mess up this time???

I should mention I thought perhaps the z+ sensor was locked, so I unplugged it. And forgot to turn off the machine, so it did a sudden little dance forward before I was able to stop it and re-attach the sensor. I’m getting afraid to touch anything as it seems to set the machine after me!

I don’t know why it won’t jog, but the black powder is probably just your pinion gear wearing. From what I read it is normal. My machine makes it.


That is a relief! I thought I had ground something important to dust!
Now, I just need to get the cnc moving again

If your spindle has hit the homing sensors (overshot) you have to cut the power to the motors and manually move the spindle off the sensors. Just a thought

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Pinion gear wear is normal, but I had what I thought to be an excessive volume of black metal filings along the top of the gantry soon after I purchased my machine several years ago. I sent photos to Avid and they ended up sending me new gears because they said the ones on my machine were from a defective batch.

So, they obvious track quality of all their parts which is impressive of them to do this and replace them in my case - good reason to do business with them.

Don’t know how your metal filing residue volume compares to what mine was but I suspect they are monitoring these posts and are already looking into this again.

The replacement gears have not produced any filings but I am a hobbiest who does not run the machine continuously.

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I have had the black residue as well and my machine dates to May 2019. Recently I replaced all the gears, so I’ll see what happens in the future.

In the lower left of the standard Mach4 window there is a one line high text box that will display messages and errors. That might tell you what is going on. For me, the most common reason the machine stops and won’t respond to anything is that one of the soft limits (which are set when the machine is homed and are there to provide extra insurance from accidentally running the machine into one of the stops). If that’s what happened, Mach4 will tell you in that text box. If that happened on the jogging tab there is a button to disable the soft limits. You should then be able to move the machine back away from the stops and turn the soft limits back on.

Or it could be another issue, of course.

Good luck!

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Here is the default AVID Mach4 window. It’s the history box in the lower left outlined in red.


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First thank you all for your help! The problem turned out to be that when the gantry homed at the start, it somehow jammed itself too far and the sensors were not letting it move, at least that’s my best theory. I unplugged everything then pushed the gantry as far back as I could, cleaned out the track, greased it, then restarted. Because it was not near the sensors, it was able to move again with the jog commands and keyboard. I ran it back and forth, up and down for a bit to make sure it was cleared, homed it, and everything went back to normal. It’s possible the gantry was slightly out of alignment, but brute force got it back.
It sounds simple, but without the feedback I got here, I didn’t even know where to start. Thanks again!!

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I agree, Avid has a loyal customer because of their support!

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That was it, I was overthinking everything and distracted by the black powder.

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