Grooves while engraving

[dvh (dietervh)]

Hello,

I’m new to lasercutting/engraving and Lightburn. I recently bought a Creality Falcon2 20W and I try to create some stamps. This works fairly well, but I get some additional grooves in the final result. It doesn’t seem to matter where I put the rubber in the working area (top right, bottom left, …). It occurs in all my test cuts so far. It doesn’t seem to correspondent with any traversal moves. I use Fill mode, 1 pass, 1750mm/min, 0.1mm interval.

The chicken is about 35 x 35 mm, the star about 20x20mm.

Any suggestions would be greatly appreciated!

[jkwilborn (Jack Wilborn)]

@dvh

doesn’t seem to matter where I put the rubber in the working area

This would seem to indicate that the problem is in the art work…

Have you watched it in preview to see if the machine is doing something different in these areas?

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What is the orientation… some of these go left to right and some up and down…

The deep grove doesn’t follow across the material, which is what I’d expect, so it sounds more like the artwork…

Some of the anomalies are deep while others appear more shallow than the rest of the engraving…

[JohnJohn (John Johnson)]

@dvh

This works fairly well, but I get some additional grooves in the final result. It doesn’t seem to matter where I put the rubber in the working area (top right, bottom left, …). It occurs in all my test cuts so far

The Deep grooves could be caused by the stack-up of ‘rounding error’ related to the holding power of the stepper motor and the Line interval. Some of the split-steps or ‘microsteps’ in between the full steps don’t hold very well.

If I knew how many belt tooth ‘pockets’ are on the pulley on the drive motor I could assume the motor has a 1.8 degree step and 2mm belt pitch and make a good guess as to which way to adjust the Line interval.

May I ask what you have selected for DPI or Line Interval?

The background ‘grain’ looks like the curtains artifact that belt driven devices make.

Wobbly lines on when both the x and y axis are moving at the same time(curved and diagonal line)

It’s possible you’re running at a speed that makes the machinery resonate. Changing the speed 20% up or down might eliminate it (if it’s resonance). I’m not certain this is relevant, but there is a Chordal motion associated with the belt tooth lifting off the belt pulleys. Russ Sadler found a cure for it by changing to a belt that is better at damping vibration and by reversing the belt so the chordal motion can’t interfere with the position of the engrave head. It shows up very clearly as st…

[dvh (dietervh)]

I doubt it is part of the artwork:

It also doesn’t correspond with any of the traversal lines:

[dvh (dietervh)]

I’m afraid I don’t have any details on the belt tooth pockets on the pulley. The laser is a (stock) Creality Falcon2.

The DPI seems to be 254, with a line interval of 0.1 mm. I think these are standard settings from the Falcon2 profile, I didn’t change anything in this screen (being new to lasercutting):

Thanks already!

[JohnJohn (John Johnson)]

@dvh

It also doesn’t correspond with any of the traversal lines:

For the Chicken (Rooster?) , check the Y-Axis belt(s) for crumbs or debris entering and leaving the drive pulley.

Is the image with the stars rotated 90 degrees to how the stars were produced?

[dvh (dietervh)]

I did some more tests, and it happens in other designs as well. There is no debris or crumbs in the pulley or belts. The belt tension seems to be OK. An engraved circle is truly a circle.

I’m engraving this at 1750 mm/min @ 100% power. Do you think a lower speed would help?

[jkwilborn (Jack Wilborn)]

If you mirror these and run them, to does the location of the grove change?

It appears to be connected to prominent areas of the graphic. That’s the idea behind using a horizontal mirror… if the anomaly also mirrors the groove.

Make sense?

[dvh (dietervh)]

I finally had the time to look a bit further to this.

It’s 100% sure that the grooves are not image related: I engraved the same image three times:

1. Bi directional fill
2. Bi directional fill, but with the image rotated 90°.
3. Offset fill

1 + 2 were engraved at the same time, 3 afterwards. (don’t mind the upper part of 1+2, the rubber was thinner there and I forgot to take this into account)

As you can see, there is some kind of overlap in the offset fill + there remains a high spot all around the ice cream as well.

Some settings:
The stamps are 30 x 30 mm
Laser used: Creality Falcon 2 22Watt
Fill settings:

• Speed: 1750 mm / sec
• Max Power: 100%
• Constant power mode OFF
• Bi directional fill
• Overscanning OFF
• Line Interval 0.1000
• Lines per inch: 254
• Scan Angle: 0
• 1 pass
• Ramp length 0.50
• Ramp outer Edge ON
• Flood Fill ON

Any suggestions to solve this issue would be more than welcome!

[NicholasL (Nicholas Leqeta)]

The grooves look like they would correlate with the edges of isolated areas of Flood Fill.

So turning Flood Fill off should fix it.

As to why the grooves are occurring?

-could possibly be over-accelerated rapid Y-travel loosing steps and not placing the start of the next fill area in exactly the right place.

-could be backlash in Y.

Either way, the over-sensitive rubber means you will have to work harder to tune your machine to get the results you need.