Hi everyone, I would like to know if someone can help me. (CNC Laser Co2 50w 40x40)
After blaming the surfaces being engraved and many other things, I’ve come up with a new hypothesis. Is it possible that my laser’s power consistency is variable?
I’ve started noticing a pattern in my engravings; some problems always appear in the same areas of the image I’m engraving. Even if I start a new engraving on a new surface, the problem is exactly the same in the new engraving. You can see it in the attached photo.
So I stopped blaming the Yetis and surfaces being engraved and started thinking that the power of my laser is inconsistent. Is this possible?
If this were possible, what could be causing these inconsistencies? Does anyone have any experience with this that could help me?
I would first start at belt tension and belt gear tightness. Then I’d look at beam alignment which would include beam exit of any air nozzle on the laser head.
Checked the belt tension and the mirror alignment. But doesn’t it seem strange to you that the graved images always fail on the same place? Both for flat objects and for the rotating one.
flat or round doesn’t matter but what matters is if the issue(lines of weak power) show up in the same position on the same axis no matter where you move your design. Is that the case? ie on the flat product, does the failure happen in the same place on your bed when you move the product/design 4 cm in direction perpendicular to the faded line?
If the faded line shows up in the exact same spot on your design then that is very different than if the faded line says in the same position on the laser bed platform as THAT indicates it’s a physical problem.
I don’t know your skills but making sure the mirrors are aligned takes testing it with the laser head at the 4 corners of the working area. The beam MUST travel perfectly vertical to the bed plane and perfectly centered within the hole of the air assist nozzle. Again, in all positions throughout the full working area of the laser bed.
In the image, we have two machetes in the same photo where the lines appear to fade in the same spot on both. On the other hand, the thermos I’m engraving always fail at the very end of the engraving process, always at the very end.
Today I did another test with one and the same thing happened, always at the very end of the engraving. (attached video). https://youtu.be/vXY8BzV1Vn4
Everything seems to indicate both things; the faded lines are in the same orientation, but they also seem to tend to appear in the same spot design every time.
That’s why I started thinking there’s something strange about it always happening in the same spots over and over again, and I’d like to know what it is.
Regarding the mirror alignment recommendation, already been through that. Mirrors are properly aligned and tested at every corner.
I appreciate any comments that can help me understand what might be happening. Regards
Until your video we could not see what you are doing. For example, when you look at the two machetes, the design is not centered exactly in the same spot on each one. We do not know if you moved the machete position or you moved the design. I don’t think you were understanding because you didn’t reference which was true. By moving the design many centimeters away from where it was originally and seeing if the same fading happens you will have eliminated something happening with the machine’s motion characteristics.
Regarding the video, we now see you’re using a rotary adaptor connected to the Y axis(? yes/no ).
For this, I would try engraving in the opposite direction and see if the fading happens at the end of the design again. We understand that with the rotary adapter your X axis scans in a fixed Y axis position so this problem here is not a position thing within your machine. Although it might be the same or different from the machete problems.
If you change your design software so that the scan rotates the tumbler in the opposite direction and the fading in the design results still shows up at the end of the program then I would start looking for things which might effect power like water temperature rising, water flow insufficient, airflow around the LPS low or insufficient. There might even be high load on the 24V output of the LPS if you do not have separate power becasue the 5V and 24V power on the LPS is very limited. One of the first things I did with my CO2 laser was to get a separate 24V power supply so the LPS would run cooler and my motors could run at full torque.
Well, I think that’s what it all comes down to in the end.. I had already checked the water flow and other many details that I thought I should check, since I had already wasted a lot of poorly engraved thermos, but thanks to your last response, you gave me a clue. When you mentioned the voltage and the LPS, you immediately thought of my small AVR voltage regulator, so I decided to do an engraving without it, and voila, the first engraving came out well.
Now I have to wait for my other engravings to come out well so I can say that I’ve finally found the problem. For now, it seems that’s what I did. Thank you very much in advance.
I’ll keep you updated on this so others can find solutions to their problems with their CNC lasers.
I’m not sure the problem has been completely resolved. Do you know of a somewhat “homemade” way to determine if the laser tube is no longer working correctly?
I’ve seen many internet tricks, but none of them give me certainty.
I mentioned a bunch of things to try and then you said you only removed a load item you’d added.
Did you do the things I mentioned and if so what were the results?
But if you just want to replace parts, the tube and LPS are wear items.
Here’s a couple of links for measuring output power. I have a Mahoney watt meter and a Dohicky, like Sadler is talking about.
About the only thing you can check it the tubes resonance mode (TEM) and it’s power. Of course, if the device supplying power isn’t giving the tube what it needs, you still won’t know.
Some tube may change TEM mode after it lases. What I mean, is it might lase at 10%, but is in mode TEM01 (doughnut shape) but as the power increases it may have a better mode.
There isn’t any good way to check the lps unless you have a high voltage meter. Even then it’s not going to tell you a whole lot. I have a volt meter on my console.
it’s likely, if you replaced the lps, that only leaves the tube. If it’s glowing pink, it’s likely not the lpls but the tube.
An lps works by raising the anode (high voltage) voltage on the tube until it reaches a trigger point, where the tube starts to conduct. This lowers the voltage, but an lps is really a current limiting device, one it starts to conduct the lps is regulating the current.
If the tube opens up, I.E. no conduction, usually results in the anode voltage getting high enough to punch through a weak spot in the connecting wire insulation.
Sorry, I still don’t know how to do an inverted scan so that the engraving starts in the opposite direction.
Regarding the two machetes: yes, both were placed in different positions on the machine bed, and the designs were also positioned differently on the machetes, without following any specific order. Nevertheless, the engraving showed the same problem on both.
Yes, im using a rotary adaptor connected to the Y axis.
I must say that the inconsistency issue doesn’t always occur at the end of the engraving process with thermos; sometimes it happens in the middle, and at other times, the engraving power simply drops off progressively as the graved proceeds. This leads me to believe it is a power inconsistency rather than an issue with the design/file or the machine’s movement at specific spots.
I didn’t quite understand this part because I’m not fully fluent in the language, and the technical concepts make me unsure about what is being discussed. I’m not sure what LPS refers to.
(There might even be high load on the 24V output of the LPS if you do not have separate power becasue the 5V and 24V power on the LPS is very limited. One of the first things I did with my CO2 laser was to get a separate 24V power supply so the LPS would run cooler and my motors could run at full torque.)
Thank you for your support; I am still trying to find the problem.
If you move the design so it’s lazing in different locations within the laser bed working area and the faded lines and/or disappearing lines move too then that eliminates something getting into the beam’s path.
There should be settings in your software driving your laser which lets you do things like rotate the laser paths including starting points. You are rastering so it makes sense for there to be ways to rotate the raster direction. Often there is a 45 deg clockwise option and a 45 deg counter-clockwise option. But you’ve moved the design and the fades have become random so it’s something else.
LPS stands for Laser Power Supply and those usually have a 24VDC output which are used to drive the stepper motors, and they have a 5V output which are often used to power a controller board and a few low power things like LEDs, a power adjusting POT(variable resistor), etc.
I forget what kind of CO2 laser you have but it’s helpful to know what it is, what your LPS looks like, what your controller board looks like and what your other power supplies(if you have any) look like.
And make sure you really know what your water temperature is by using an alternate means of measuring it to verify any built-in system is accurate. And the water flow should be robust. Many use a clear rotating vane mounted in view to always know the water pump is on and working.
It’s really odd that on all 3 of the images(mug and 2 knives) there are 3 faded lines yet the OP said they moved the design around on the work area and the faded lines still show up. They even said the lines seem to move around randomly even though in all 3 pics they seem to be in a similar pattern. It sounds/looks physical/mechanical but they’d said they’d checked everything. Could a cracked lens do something like this? I mean if the beam is aligned it’s not moving across the lens so I’d think it wouldn’t show up as 3 dimmed areas. hmmmm
