Missing engraving dots on successive jobs

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Joncon00
Posts: 2
Joined: Mon Jul 15, 2024
Location: Beacon NY
Country: USA
Laser Machine Make or Type: Custom Laser Lathe
Laser Power: 100W
Laser Bed Size: 96"x3"
Home Position: BL
Control Software: LIGHTBURN
RDWorks Version: NA
LightBurn Version: NA
Ruida Controller: Other
Windows Version: 11

I made a custom "Laser Lathe" to produce lighting parts. It has this issue where after a few successive runs of the same engraving job it will start to produce spiral patches of unetched areas where the laser did not seem to fire. Usually after about 10-20 minutes of running.

My machine is featured here.
https://www.grbl.org/100-watt-rotary-custom-laser

The setup is built on a 100W Reci Tube and basic cloudray power supplysupply. The motors are nema23 steppers with integral drivers which drive X and A axis. The controller runs GRBLHAL to interpret our custom gcode. There are three mirrors that that direct the beam to a fixed head. The parts being etched are on a rotary mounted on a sled (axis). The included image shows parts made with the same exact program but producing different appearances. Baically the density of dots should be a smooth gradient without any spiral or empty patches like #3 & #7 in the image. With some discussion with the designer of the controller I have tried:

Changing out the pwm line from the controller to laser ps to a shielded cable. No change
Checked the thermals of the controller. Everything was cool. The water temperature stays between 18-20C
switching computers to send the program. Seems to help initially

Looking for ideas on what further to look into. Thanks in advance!
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Gareth Lewis
Posts: 105
Joined: Mon Jan 03, 2022
Location: Aberdare, RCT, Wales
Country: United Kingdom
Nickname: Gareth
Laser Machine Make or Type: Tangerine Tiger
Laser Power: 50W
Laser Bed Size: 300 x 500
Home Position: BL
Control Software: RDWORKS
RDWorks Version: v8.01.47
LightBurn Version: v1.5.03
Ruida Controller: RDC6442
Windows Version: 10
Accessories: Rotary Unit, Camera, digital millammeter, digital thermometer readout
Contact:

Hi JonCon00

My original thought would be the cooling system, even though it's cooling to 18~20C.

Russ Sadler did a video on the cooling effects of the CW5200 chiller on the laser beam https://www.youtube.com/watch?v=PJw-3uK6ZfM&t=1s

It could be that your cooling circuit is being aggressive when it kicks in after 10~20 minutes causing changes in the laser performance. It may be a case of you just needing to adjust the settings on your chiller.
Gareth Lewis
Forum Owner & Administrator
LaserUser Forum (formerly RDWorksLab)
💬 Join our community of laser engraving enthusiasts!
📧 Need help? Contact me: admin@laseruser.com
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Gene Uselman
Posts: 2180
Joined: Thu Jul 07, 2016
Location: Suburban Minneapolis, Minnesota, US
Country: USA
Nickname: Gene
Laser Machine Make or Type: QC
Laser Power: 130W
Laser Bed Size: 900x1300
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: RDw .19 & Lightburn
LightBurn Version: Latest
Ruida Controller: RDC6442
Windows Version: Win 10 Pro
Accessories: I have a combining lenses, pin tables [homebuilt], honeycomb tables , wireless remote, Modifed Ultimate Air Assist, home built non-powered rotary device, PrusaMK4 and Mini Prusa printers.

I am loving the aluminum extrusions [80-20 in the US- altho I use 2020 too]. If this is not proprietary I would love to see more of this. Gene
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User avatar
Gareth Lewis
Posts: 105
Joined: Mon Jan 03, 2022
Location: Aberdare, RCT, Wales
Country: United Kingdom
Nickname: Gareth
Laser Machine Make or Type: Tangerine Tiger
Laser Power: 50W
Laser Bed Size: 300 x 500
Home Position: BL
Control Software: RDWORKS
RDWorks Version: v8.01.47
LightBurn Version: v1.5.03
Ruida Controller: RDC6442
Windows Version: 10
Accessories: Rotary Unit, Camera, digital millammeter, digital thermometer readout
Contact:

Gareth Lewis wrote: Tue Jul 16, 2024 Hi JonCon00

My original thought would be the cooling system, even though it's cooling to 18~20C.

Russ Sadler did a video on the cooling effects of the CW5200 chiller on the laser beam https://www.youtube.com/watch?v=PJw-3uK6ZfM&t=1s

It could be that your cooling circuit is being aggressive when it kicks in after 10~20 minutes causing changes in the laser performance. It may be a case of you just needing to adjust the settings on your chiller.
Hi JonCon00

Did this suggestion help at all?
Gareth Lewis
Forum Owner & Administrator
LaserUser Forum (formerly RDWorksLab)
💬 Join our community of laser engraving enthusiasts!
📧 Need help? Contact me: admin@laseruser.com
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