Horizontal bands not engraving with full power?

Community Laser Talk
#1

Hello Folks,
I’m hoping someone with the right experience could weigh in with comments about some visual bands while Bi-directional vector engraving. 2.5% Overscan, 0.1mm Interval. Cross-grain on 3mm birch ply.
It looks like the laser isn’t at full desired power on occasional scans, and primarily on right-to-left scans and then resumes to full strength. These marks appear randomly and not consistent when engraving the same file again.
Reci T1 (75W) and Cloudray MYJG-100W power (rated 80-100W)

I’m a new user so I’m not able to upload photos to the forum yet, but you can have a look here:

I’m using LightBurn and the LaserBoard, onboard drivers, with the following config if it matters:
alpha_step_pin 2.0 # Pin for alpha stepper step signal
alpha_dir_pin 0.5 # Pin for alpha stepper direction
alpha_en_pin 0.4 # Pin for alpha enable pin
alpha_current 0.4 # X stepper motor current
alpha_max_rate 24000.0 # mm/min
alpha_acceleration 2000 # mm/sec²

beta_step_pin 2.1 # Pin for beta stepper step signal
beta_dir_pin 0.11 # Pin for beta stepper direction
beta_en_pin 0.10 # Pin for beta enable
beta_current 0.6 # Y stepper motor current
beta_max_rate 24000.0 # mm/min
beta_acceleration 2000 # mm/sec²
Please let me know if I’m missing anything useful.

Thanks in advance for anyone who recognizes this, and could offer some advice.

#2

Hi Oliver,

Welcome to the forum! Thanks for providing the photo links and details. I have upgraded your trust level so that you can now upload photos to your posts.

Do you have Smoothie Clustering enabled in LightBurn? Can you double click to open the layer settings and provide screenshots (no cell phone pics, please) of the entire LightBurn window for the file you are working with?

For the top portion of your image, if you have any other appliances on the same circuit they could cause banding as they power cycle (like your chiller kicking on/off to maintain temp). Isolate the machine on a separate outlet and see if it helps.

image

Part of what I’m seeing in the lower section appears to possibly be inconsistent wood composition. I’ve seen this before when burning wood that has thick, dense areas or glue spots, which is in line with the random engraving results.

image

Some other possibilities to research:

#3

Hi Starla,

I appreciate your comments, Thank you!

Smoothie Clustering is not enabled, so that’s definitely a start. Most of my use is line art and cut so this hasn’t been on my radar.
Also the chiller is on the same circuit, so another possibility.

I’m only about 0.16mm down on the deepest/intended portion of the engraving, so not quite near the glue layer. The “curtain” area is only 0.12 at the lightest portion, and then tapers off the the intended engrave depth. I’ll continue with Russ’ videos and see what I can apply to my situation.

Here’s a screenshot of the layers. The Advanced tab only has Ramp at 0, and Flood fill is off.
I combined the Device Settings onto the screenshot so everything is there. Here you can see Smoothie Clustering was off:

lb2
lb24002×2185 1.84 MB

I’ll experiment a little and report back in a day.

Thanks again and stay safe!

#4

Hello again,
I wanted to check back to report I’ve found the source of my strange banding.
I changed the scan angle to 45deg and it appeared to improve, and at 90degrees the banding effect is completely gone. So mechanical artifact! I’ve never been in love with the do-everything gantry extrusion, and this gives me a reason to upgrade to a more precise gantry.
Here’s a photo of the improvement when I turned the scan 90 degrees:

scan2
scan22016×980 280 KB

Thanks again for you assistance,
Oliver

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