Accuracy issues after Z axis upgrade

I seem to be losing steps… tried a test cut of s simple rectangle…6" X 3" and specs are off by 1/8" on both axis. I did recently upgrade my z axis with a 6 inch kit from CNC4newbies. I did change some GRBL after checking with the forum. Up till than my machine has been extremely accurate. I do love my X carve! Because I am not GRBL literate I am inquiring here. I thought about the possibility of adjusting pots on the X controller but the machine had been very accurate till recent upgrade. Thanks ahead of time for all help. The community has always been very helpful. Cheers. Happy New Year!

What GRBL settings did you change?

These were the instructions I followed:

In Easel, go to Machine -> Advanced -> Machine Inspector. In the console, send “$$” to get all your current parameters. $102 is your Z-axis steps/mm. To change, just send “$102=###” with the appropriate number value.

What was the “appropriate number value” you used for $102?


Where are you losing steps?
How do you know you’re losing steps?

The more info you’re able to provide, the easier it is to diagnose an issue.

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You stated 1/8 off. Was it larger or smaller?
I suspect larger and that would indicate that you previous settings accommodated the play in the original Z assembly.

To test accuracy I am cutting squares using Easel. I have a 1000mm set up. I upgraded the z axis with a slider from cnc4newbies. It is the belt driven model giving me 6 more inches in clearance. The only change I made in my GRBL was the $102=59.059

No matter what size square I cut( cutting on path) both sides are short by roughly an 1/8" every time. Up until modifying the machine it was highly accurate. I have adjusted/tensioned and tightened all belts. checked all screws, etc…

Are you taking into account that you’re cutting on path? What size endmill? 1/8"?
A 1/8" endmill, when used to “cut on path” will make a square 1/8" shorter X&Y than it was drawn.


here are my GRBL settings

Jon - if you draw a 10" square, use a 1/8" bit and set it to cut inside of path, that is the pocket width in the X and Y direction?

I’m surprised your X & Y GRBL values are defaults as well. Did you calibrate all 3 of your axis?

Traxter is correct is am surprised the those were accurate at default settings. I had to tweek mine a little.

maybe you should share your easel project so we can validate the toolpaths?