Engraving issue: slow power up ramp, offset image

Hi there,
i am using a Ruida RDC6442 and have already tried 3 different power supplies, without change.

The top is engraved with 400 mm/s, the bottom with 100 mm/s. Both bi-directional.
Is there a setting that can cause this distorsion?

Have you tried slowing down too 100mm/s?. If it looks good maybe do the offset adjustment.

I assume your sign is not quite long and wide, maybe 50x25mm or something like that. When you push the accelerator to the bottom to reach 24000 mm / min (400 mm / s) you must already step on the brakes again to have time to stop and turn and accelerate again …
I would like to make a series of different speeds to find the optimal speed, for a satisfactory workpiece quality but also to find the speed the machine can handle.

Its not a setting, it’s mechanical backlash. I would have said mechanical/electronic, but the offset is nearly the same for 400mm as it is for 100, which lets the laser subsystem off the hook.

Thanks for the input! Sorry - i forgot to mention: This appeared after installing a new laser tube.
Here is another sample where i used mono-directional filling on the top and bi-directional on the bottom. Both 400 mm/s. The untouched frame around the engrving should be equal on the left and right.

Hi Jens, maybe a silly question but is the replacement tube the same power as the old one ?

I ask because as well as scan offset I was thinking that if the power supply was not capable of generating the required pulse strength at the frequency required for your scan speed, a lag could well look like the results you are getting, theoretically of course



the replacement tube is only 100 W, the replace one had 160 W. I friend gave me a 100 W power supply for testing, but i found no difference to the original 38 mA power supply. So i gave it back and run the machine with the 160 W power supply. I added mA meter to the machine and take care not to run it with more than the 25 mA that is written on the tube by changing the Ruida controller parameters for the tupe.

25 mA equals 46 % power in lightburn at my setup: Is it possible to let Lightburn convert 100% power to Ruida’s 46%??? That would make life a bit easier.

I am using the huge machine (2 x 3 m) to cut sheets of rubber, that not willing to ly flat on the bed. To compensate that i mounted a 6" focus lens that has a wide usable focus distance.
I learnt a lot by watchin Russ’s videos in the last days. Russ notes that the laser tube needs 3ms to power up, that equals my distortion with 400 mm/s. What puzzled me totally and made me to open this thread is that the powering up area is not 4x wider at 400 mm/s than it is at 100 mm/s on my first picture up in this thread.
But i made more tryouts and found that my laser point is about 0.3mm in diameter.

Going slower helps but if you want to engrave a pattern that is more than 1m wide you are happy for everything that saves time.

Where do you end up with your speed? Regarding length and speed relations, I do not think it is a linear propertion, the distance is too short to be able to perform the real acceleration and the real deceleration at the given values

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