Incomplete circles at lower power

[ferpando (Fernando)]

Hello,
I’m pretty new with lasers and still testing materials to find out speeds and power.

I want to cut/engrave paper and on my tests there’s something weird going on.
If I use low power (so the laser does not cut through) circles are not complete.
I tried to set the laser to constant power but no change.
The problem seems to get worse with speed and it desappears after increasing power to 30%.

What I don’t understand is if the laser can mark the paper at 15%, why does it stop at mid circle?

It seems to affect only oval shapes, becasue the rest of the characters (besides 0) engrave correctly.

Any help would be appreciated.

[ferpando (Fernando)]

Made another test…
Increased the speed of the numbers to 1000 / 20% and they started to dessapear more.

Also lines and rectangles.
I guess the laser is reflected and only catches at some points.

Also the engraving part is almost right through.

I’ll repeat the test with a darker paper.

and the original:

[ferpando (Fernando)]

I guess the color of the paper has much to do with the result.
Same settings:

[ferpando (Fernando)]

final test for this matter…
Slightly thicker cardstock.

[misken (Melvin)]

Can you confirm that the laser was still in operation at those circles? Or was it turned off at that locations? If you already used constant power (that was my first idea), then I could think of a connection issue at the laser module which happens at fast movement changes.
Here is a guide on how to check mechanics and another one on settings:

Guide to mechanical adjustments and maintenance

Settings guide - Diode Laser Wiki

[ferpando (Fernando)]

Yes the laser was on.
I could see the dot on the paper.

I guess white paper reflects too much energy because the darker the paper the sooner it cuts or marks.

[misken (Melvin)]

Yes, true. White / bright colors are not very suitable for diode lasers because they reflect light too much.