Laser firing early when engraving

[daveman]

I am running a X7S controller on a custom built laser cutter. When I cut, it works great and all measurements are spot on. When I engrave, the engraved items (text or image) is shifted to the left where it appears the laser is firing early when engraving unidirectionally. When doing it bidirectionally, the engraved items doubles, firing early in both directions. Belts are tight, no real backlash that I can can measure, if there is any it shouldn't result in the 2mm offset at 200mm/s. Acceleration settings have no impact on the issue but speed does. The higher the speed the more the image shifts to the left, indicating that the laser is firing early (faster speeds make the preignition more prevalent). Is there a compensation factor that can be adjusted for power supply trigger times, my power supply has a pretty fast trigger time? Any ideas? Thank you in advance for any assistance.

Thank you,
Dave

[daveman]

I am running a X7S controller on a custom built laser cutter. When I cut, it works great and all measurements are spot on. When I engrave, the engraved items (text or image) is shifted to the left where it appears the laser is firing early when engraving unidirectionally. When doing it bidirectionally, the engraved items doubles, firing early in both directions. Belts are tight, no real backlash that I can can measure, if there is any it shouldn't result in the 2mm offset at 200mm/s. Acceleration settings have no impact on the issue but speed does. The higher the speed the more the image shifts to the left, indicating that the laser is firing early (faster speeds make the preignition more prevalent). Is there a compensation factor that can be adjusted for power supply trigger times, my power supply has a pretty fast trigger time? Any ideas? Thank you in advance for any assistance.

Thank you,
Dave

Correction!!
I now believe the laser is firing late. I upped the belt tension by adding a second spring tensioner, which if it is a backlash issue should have at least some effect, it had none at all. I have fixed the issue (only for bidirectional engraving) by using LightBurn to add a positive 1.375 offset per 100mm/s of speed (i.e. 1.375@100mm/s, 2.75@200mm/s, etc.). This does not work for unidirectional engraving but works perfectly for bidirectional. I do think I am dealing with a power supply timing issue which I do think is firing late not early.

The Build:
NEMA 23 on X and Y, 2/1 reducer on Y
DM556D on both axis running at 12800 microstepping <- This may be part of the problem, will reduce and retest. This is way too high for these controllers
OpenBuilds V-Slot construction for slides
Table dimensions 630 X 460
Probably have some pretty decent mass to the X and Y axis which is why I went with NEMA 23 motors
MaxAcc is 4500 for X, 800 for Y (higher distorts engraving as it is still lit during acceleration/deceleration band)
SPT C45 Laser Tube
Cloudray Laser MYJG-50 power supply
LightObject X7S controller running firmware 1.19.5.8

[daveman]

I am running a X7S controller on a custom built laser cutter. When I cut, it works great and all measurements are spot on. When I engrave, the engraved items (text or image) is shifted to the left where it appears the laser is firing early when engraving unidirectionally. When doing it bidirectionally, the engraved items doubles, firing early in both directions. Belts are tight, no real backlash that I can can measure, if there is any it shouldn't result in the 2mm offset at 200mm/s. Acceleration settings have no impact on the issue but speed does. The higher the speed the more the image shifts to the left, indicating that the laser is firing early (faster speeds make the preignition more prevalent). Is there a compensation factor that can be adjusted for power supply trigger times, my power supply has a pretty fast trigger time? Any ideas? Thank you in advance for any assistance.

Thank you,
Dave

Correction!!
I now believe the laser is firing late. I upped the belt tension by adding a second spring tensioner, which if it is a backlash issue should have at least some effect, it had none at all. I have fixed the issue (only for bidirectional engraving) by using LightBurn to add a positive 1.375 offset per 100mm/s of speed (i.e. 1.375@100mm/s, 2.75@200mm/s, etc.). This does not work for unidirectional engraving but works perfectly for bidirectional. I do think I am dealing with a power supply timing issue which I do think is firing late not early.

The Build:
NEMA 23 on X and Y, 2/1 reducer on Y
DM556D on both axis running at 12800 microstepping <- This may be part of the problem, will reduce and retest. This is way too high for these controllers
OpenBuilds V-Slot construction for slides
Table dimensions 630 X 460
Probably have some pretty decent mass to the X and Y axis which is why I went with NEMA 23 motors
MaxAcc is 4500 for X, 800 for Y (higher distorts engraving as it is still lit during acceleration/deceleration band)
SPT C45 Laser Tube
Cloudray Laser MYJG-50 power supply
LightObject X7S controller running firmware 1.19.5.8

Further Update:
Setting DM556D to 6400 microsteps had no effect
Also loaded the config in a AWC608 controller laying around, same problems so it is definitely in the machine somewhere.

[Tech_Marco]

Try to use "Falling edge" on system configuration

Micro-stepping: 4000
X acceleration: 8000
Y acceleration: 4000
Space_jerk: 30,000
Cut)jerk: 20,000
Speed_Factor: 1.5
Space speed:200
Start speed: 10

Do not put too much tension on the belt. Doing so will damage your bearing.
Give it a try

Marco

[daveman]

Try to use "Falling edge" on system configuration

Micro-stepping: 4000
X acceleration: 8000
Y acceleration: 4000
Space_jerk: 30,000
Cut)jerk: 20,000
Speed_Factor: 1.5
Space speed:200
Start speed: 10

Do not put too much tension on the belt. Doing so will damage your bearing.
Give it a try

Marco

Thank you Marco, will do. As always, fast with a response. Thank you! I will post a follow up when I can try it out.