Black spots in my text

Font Calibai
Speed 300
Power 10%

The head moves so fast when it changes directions it shakes the machine.
The bed is adjustable on screw posts and will move slightly when the machine shakes.
that is what is causing the distorition in the text.
What I want to get rid of are the dark spots in the engraved text so the text looks evenly engraved. My Diode laser has no such problems.
attached are two photos showing the engraved text and the machine settings.

Reduce the acceleration, to make the head move off slower.

Set your MIN power lower, so it can reduce the power when it slows down around corners/curves

SAVE you settings before you change anything!!

1 Like

It’s not kosher on this site to double post. It costs all of us time trying to help and confusion over the same issue.

This is the same issue, with the same response from someone else.


Min power is already set as low as it will go.

Jack, I could not find my post in the other forum and thought it was deleted because it was a hardware problem and not a software problem. So I posted it here with better photos.
Sorry to offend you but I am not getting much help here. Told to reduce min power when it is already as low as it goes.

They don’t ‘delete’ stuff because it’s in the wrong bucket. If they feel it should be moved they will move it.
It’s not just me. You got @LaserCuttingPro to answer the same question with the same answer.

Just don’t do multiple posts for the same issue.

Don’t let it keep you up at night… :crazy_face:

How well will your diode laser cut clear acrylic or engrave glass directly? I doubt it does…

You’re comparing apples to oranges. Not only are the operational frequencies different, but there is an immense difference in power levels between the two.

There are physical limits to these machines. 50 watts may be too powerful for you do this type of engraving, the way you are doing it. At 10% it’s still 5 watts and the characters are so small. Your ‘speed’ is probably never attained since there is no acceleration area doing a vector. It does the best it can for the area it has.

The reasoning behind a maximum/minimum power is to eliminate/reduce exactly the problem you are having. When you set max/min to the same values the controller has no choice but to use those values, even going around corners where it has to slow down.

If the laser is too powerful for that application, we can’t ‘lower’ it. Both of us advised lowering power, which you can’t do.

It is a vector and/or single stroke font? You have not answered this question.

If you don’t answer what’s asked of you, our answers may not be correct or applicable.

If this is a vector, another approach I use is to convert it to a bitmap and scan engrave… That will get rid of the ‘spot’ issues… but with everything, there are tradeoffs.


Using a 50W C02 laser I am getting black dots in my letters when engraving words using “lines”.
Power is set to 10% with speed at 200 (the faster I go the more the head acts like a vibrator)
I have my low power set to 10% also.
Is there a setting that will eliminate this?

It’s burning when it goes around corners, so if possible lower your minimum power. Are these single stroke fonts? How are you doing this?

Not sure what you mean by vibrating… I also have no clue to the size of your text… business card or 2 foot square.

10% power is pretty low. My machine won’t consistently lase below about 9.5%.

I did notice this in the center of the ‘S’

Screenshot from 2022-06-17 12-05-44

Is it in the font?


That distortion is due to the vibrations from the laser head osculating as it burns the letters.
The head moves and reverses directions so fast it is like an unbalanced washing machine on spin cycle. The table will shake. the table is mounter on 4 screw posts that raise and lower it and there is a small about of wobble or play in it. Even with the speed set to 200 it goes to fast and causes the shaking of the machine. it is not a problem on larger text … just the small stuff. If I lower the speed then the text is burned darker and deeper. Running power at 10% so I cant lower it any more. Text is small 6mm or less in size. Yes … it looks like it is slowing down on some corners or possibly overlapping a bit causing a darker deeper line. I am using my 10W laser diode engraver to do the lettering till I can figure out why the C02 laser is doing this.

The acceleration is too high for the machine, I would guess. What kind of acceleration speed is your controller set?

I can run my 50 watt “China Blue” with a modified head at 1650mm/s, so there is some kind of issue if you are getting variations from a speed change. Before I changed out the head, it had no problems at 500mm/s…

I would double check the acceleration values of that axes. Are those single stroke fonts?


200 could be pretty fast… or it could be pretty slow…
What units are you using?

The results look like you’re still running a little bit fast for the machine.

You may have some mechanical backlash.

Have you attempted this as a scanning or raster engraving? It will show backlash and overscan issues very clearly and when addressed should help square up the strange shapes in the letters.

Moved and merged…
Just got back from a few days off and still catching up.

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