I have purchased a laser (Chinese one) 140cm x 90cm workspace, 130watt.
So far so good. In general it works great.
Engraving and cutting, no problems there. Except when cutting round-ish corners. Then a wobble is visible and I can’t figure out where to look. This is especially visible if I cut small circles fast. I has the same wobble on every spot on the bed.
It has the same wobble, on the same spot but if I start from the end instead of the beginning.
Does anyone have any idea if this is X-axis or Y-axis related?
I have tried the software adjustments that are recommended
Tightening of the lens and mirror.
Belt tension
All suggestions on how to solve this issue are welcome.
Attached I have a picture where the wobble is clearly visible and it occurs at the same time in the job. Even if I reverse the starting point, same wobble.
Hi @sensor if you’ve checked all your belts, nothing is loose and there are no mechanical tweaks you can make, then you’re simply going too fast. On that part of your drawing/shape, most likely your lens head is having a bit of a wobble due to inertia and changing direction. If you are sure nothing is loose like the lens or the nozzle? Does your machine have a lot of extra stuff on it for auto focus or air assist regulation or anything like that? If its a heavy head and you’re going fast, things will wobble a bit.
Here are more things to check and try.
Check your Y rails are secure and evenly clean and that the Y belts are evenly tensioned.
Check the tension (again) on your X axis belt. Don’t over tighten, also check the mountings for your X axis running gear, pulley and the block its attached to.
You might consider reducing the min and max acceleration on your controller.
I can’t tell you what might be right for you (I’d tell you just to go slower) some experimentation is needed. Be sensible, don’t change anything before writing down what you have. You can really mess up your setup in there.
You’re looking at mechanical flexing in the laser head + gantry as it decelerates to zero after rapid Y axis motion. Because it’s a large machine, it will have more gantry flex than on smaller machines. There may also be a bit of belt flex, but that’s not the major problem.
The main problem: the laser head is a large off-center mass screwed to the X axis bearing follower through a bent sheet metal bracket. That it wobbles only a few tenths of a millimeter is the surprising part of the story.
The Mirror 2 mount on the gantry is another collection of bent sheet metal that flexes with fingertip pressure. Whether that happens under normal gantry motIon remains unknown (by me, anyhow), but it certainly can’t help.
Reducing the maximum Y axis speed by a lot will help, with the corresponding penalty of slowing the machine’s overall motion. The controller has several completely undocumented speed & acceleration settings & factors, not all of which behave as you’d (well, I’d) expect from their names:
What a super interesting read. That is exactly what I am seeing!
I am going to fiddle a bit with some other settings..
See what speed the Y will have the least wobble and if I am willing to live with that
Or change to another head or something.
Many thanks for this informative read of your experiments.
You haven’t mentioned Line Shift Speed (if this is like the other Ruida)
that sets the speed it jumps between line (but Jump Speed is a different parameter)
The wobbulation may actually go away with higher speeds. I don’t see it on our CO2 lasers, because the controller looks at machine settings accel and the commanded speed and adds enough extend space for it brake, turn around (the line jump should happen here), and accel back so it will be at constant velocity where it actually has to raster.
With very low speeds, there’s no extend space, so it’s jumping without any room to stabilize. Hmm.
Setting the Line Shift Speed much lower probably won’t have any effect on runtime. I see examples on Google set to 50 or 100mm/s. But these jumps are usually like 0.2mm, so if it was 10mm/s it would still only take 0.02sec per jump.
Actually, why is this field even a thing?? For small jumps like 0.2mm, at 2000mm/s2 accel, it has to switch to decel at the midpoint- the peak velocity it could get would be only 0.632 mm/s!!
Well, to be fair, the Ruida lets you put anything in the Line Interval field. I did some amazing work with 1mm LI and lowered the Z until the beam spot increased to 1mm and made HUGE raster posters in just a few minutes.
But your LI would have to be >5mm for it to reach 100mm/s at the midpoint.\
So…. I’m not sure how reducing Line Shift Speed would have an effect, because it shouldn’t ever be reached in any real-world scenario
Still annoying that this is something I have to live with. Long live the wobble..
Quite some settings I still have to try. On the other hand now that I think of it.. I changed the Ruida board with a newer one..
I am not sure if that wobble was there with the original one.
Lets see if I find time to switch with the original one might be some setting somewhere that I missed to copy.
