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Guide to tweaking power, speed and passes towards reliability

One of my struggles has been to understand what happens to the effective laser  power applied to materials when speed and power are adjusted.

Its too unreliable (for me) to just slow things down or speed up;  Too slow can equal  extra soot marks or even fire, speed up usually means an incomplete job…  

Yes, I often add in an extra pass or two at the end of a job to finish off.  Time consuming.

I needed a guide (based on a test-cut / etch that worked) that would extrapolate to slower - less passes or faster - more passes to tweak things reliably.

I came up with the following on a spreadsheet.  It seems to “work”.

If someone can correct my physics and the “Power Applied” formula, I would appreciate it.

The spreadsheet itself wouldn’t import here, so I did it in text bits.

“A” is the Power column, B is Speed, D is number of passses…

I have only tried this on 100% power so far.



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Thanks for creating a thread on this! Look forward to see what everyone is trying and what works.

Nice spreadsheet Michael. I was doing the same thing for a while but just on paper. Your formula looks good.

One thing I only realised after switching to Lightburn was that if talked about speed in mm/s rather than mm/min I could refer to it as a percentage since the max speed of the E2 is 6000mm/min or 100mm/s. It is not as precise however unless your using decimal points.


using the same method you have @Michael Jessop, I have found cutting 3mm black cast acrylic cuts best with an applied power of 2 and above.

So on your chart, it should cut drop straight out after cutting using a speed of 400 with 8 passes, 275 at 6 passes, 180 at 4 passes.

And at speeds below your scale, 150 speed at 3 passes, 125 mm/min at 3 passes, 100mm/min 3 passes and lastly 100mm/min at 2 passes…

they all take the same time to cut though but 150spped at three passes gives great results.


That’s great work! I wold like to do some cutting with acrylic and styrene. You have given me valuable pointers.

So after a few more cuts inother materials

3mm MDF cuts cleanly and drops out at an applied power over 1.5

and 3mm ply cuts out cleanly at an applied power of 1.7 and above

hope to try this out on leather and felt in the next few days

An update on the spreadsheet:


I should try the mm / sec, sometime - to get  applied power as a %…