Work Gouged by Bit

Set up my machine to carve lettering font 3mm deep. I am a beginner. All goes well untill half way through; then the bit starts cutting into the work as it moves around the cut pah leaving straight linking lines in the carve. Eventually the job ends and the mill goes back to zero, leaving a 1mm deep trace through the work.

I assume that the safety height has changed half way through the program.

I am using Easel and a ‘Pro’ day. Day and stock wasted. Ho Hum.

Help. This is all greek (or GRBL) to me

What’s probably happening is that your z axis lost a few steps, so the machine “thinks” it’s at a higher point than it really is. Things to start checking are the pulley on top of the Z axis, and all the bits that go up and down there.
Also check out that your calibration is correct, i.e. when you jog up 20 mm (or whatever) the z axis goes up the correct amount. Although that probably wouldn’t cause the problem you had, it’s good to check.
If your cutting moves are too aggressive that can cause things to slip, as well.
To start with I’d spend some minutes jogging the z up and down as far as you can and check that each cycle you return to the same spot.

Not withstanding on what MikeByrne said, but I had an issue where the bit slipped down some out of the router and caused a similar issue. I would measure the bit length from the router before and after, that’s how I found out what was happening to me.

There have also been cases where V-carving caused unexpected drop-downs, and these are visible in the preview/simulation.

Please share your project here and we can see.

Sorry for the delay. The issue was that the z axis had indeed altered iself from its proper stepping. Don’t know how or why but once reset all isues are gone