Darkly Labs Community

Z Offset, Z steps and MDF

 Can I have, please, a “for dummies” explanation of these options in the cuts menu?


I get it that “Z Steps per pass” lowers the laser head on each pass.


I don’t get the Z Offset bit.    What does it actually achieve?  -  I read the prompt and get the point of defocussing to achieve a wider burnt scan,   but it  doesn’t seem to help with deep cuts.          Is it up or down by default?        Can it be Plus (up?)  and Minus (down)?                     Is it once only, then back to calibration - plus or minus as commanded in Z Steps?       I have some trouble with some angles giving incomplete cut-through on 3mm mdf; I hoped the Z Offset might address this but it seems to make no difference.               I have calibrated a few times;  Under Laserweb it was -2.27,   Under LightBurn I find it hard to pick between -3 and -4.  Using a magnifier and the eyes of another  I chose -4mm.    Do fractional settings work - e.g. -3.5?

Oh, and I wonder of I have got a batch of MDF made of tougher wood and smoky glue?  The earlier material ( darker mdf) gave cuts  that were much closer to the Library settings.  Now I am going 180mm/m @100% x 4 to get cut-through.

Thanks in advance


Z-offset would be primarily used for shifting the focus for a single pass, or having the first pass of a multi-pass cut start deeper than the surface. It’s mostly useful for CO2 lasers.  If you change the Z offset value it actually tells you whether you are going into or out of the material (positive values are up, away from the material).

The calibration value for the Emblaser is currently stored as an integer, so decimals will be truncated.  I asked Domenic about this and he suggested that occasionally storing a half-value can be useful, so I’ll make a note to alter this to store a digit after the decimal for our next release.


because I have a problem with complete cuting of wood here my question … is this correct that positiv Z offset values are away from the material top.

I see in LightBurn cut menu that there is the designation “in” with a positive value and if I use a negativ value the i can read the designation “out”

Now i’m a little confused. Thanks in advance for helping and sorry that my english is not so good.


I had the same confusion.

It helped when I discovered the new driver software allowed me to run the laser head Z axis up and down “live” (laser off!)with those controls.

Hi Michael,

I am very happy that not only me have a problem with this.

Thank you very much for your perfect help.

Since I believe that you already have a lot of experience, I still have a question … I have tried different cuts in MDF with different Z offset’s.

Unfortunately, I could not find any visible differences.

Can it be that I have fundamentally wronged?

In which cases does it make sense to use the Z offset?

I am looking forward to an interesting answer so that I can learn something more.

Thank you and friendly regards


I have just run some tests with 3mm MDF as I am noticing my E2 performance isn’t that great at the moment (could be the quality of the MDF)

I used to start my cuts at 1.5mm down into the MDF (half way)
And that was what was recommended.

I did a focus calibration before the tests

Today my tests show that actually I will get better cuts at only 0.5mm or 1mm down into the material

Emblaser2, 3 passes, 100% power, 150mm speed just cuts through the 3mm MDF

Also, my tests show that for this material there is no advantage in dropping down lower for each pass (was trying 0.33mm per pass)
I am better off leaving the z axis at 0.5mm or 1mm where it started.

Hope this helps someone.
Cheers, Tom