5.5w vertical lines recent cutting problem (not wood grain)

[toromand]

Hi, first some info:
5.5w laser module with low power button on top
L7 control board
40x50 frame machine
T2laser software (great - highly recommend)
1.1e grbl (default)
Now the problem - everything seamed fine for a long time until couple days ago when I noticed significant difference in cutting 3mm plywood horizontally and vertically. Turning the plywood 90deg didn't help - nothing to do with the wood grain.
My horizontal lines cut just fine but vertical seems like the power is "trembling" and the line is kind of perforated, barely through the back side, not fully cut.
I am aware that my laser beam is a bit square (not round) and that vertical lines are wider because of that. Is it possible to make the vertical resolution bigger for the y-axis motors in order to compensate for this as I think this might help?

Also I have noticed that when I use the button on the laser module to additionally lower the beam while positioning the laser - now the difference is less noticeable.

Can my problem be related to the laser power module?

Anyone has a clue?

[Zax]

I haven't seen this problem exactly but it could be due to lower laser output, and since the beam focus isn't regular (wider in one axis) the power density is lower still.

[toromand]

Yes... I thought so myself.
BTW I just noticed the laser housing gets more hot then usual. Do you think changing the power module could help or it is more likely that it's the diode?

[Zax]

I would say the diode most likely, is the fan running normally?

[ggallant571]

What is the power rating of your 12V supply?

Another possible cause is the Y stepper motors are drawing too much power.

[toromand]

I would say the diode most likely, is the fan running normally?

Yes, the fan is spinning, although it's below the electronics. I should disassemble and clean, I guess.

[toromand]

What is the power rating of your 12V supply?

Another possible cause is the Y stepper motors are drawing too much power.

It also crossed my mind, but I could not find a proof. Also checked with a spare controller board. Also checked spare lens... The fact that it's running a bit hot concerns me.
It should be enough, having 4-5 Amps... Checked for voltage drops while moving, I cannot see any. (Also it was working fine before)
I have also checked settings on  the drivers. It also seems fine.


I ordered a TTL power board to see if it can improve things, and will report back when it arrives.
If it's the diode, I guess I can reduce the power a bit and use this head for engraving some more time,and buy another one for cutting...

[ggallant571]

I started with a 5.5V for cutting, then engraving, then the junk box. Bought a 1.6W unit that cuts and etches better. Then purchased a 2.5W for etching on slate.

I recall that the 5.5W uses about 3.5A at 12V. Do you have a bench supply with power meter?

[toromand]

I started with a 5.5V for cutting, then engraving, then the junk box. Bought a 1.6W unit that cuts and etches better. Then purchased a 2.5W for etching on slate.

I recall that the 5.5W uses about 3.5A at 12V. Do you have a bench supply with power meter?

I believe it will be my case also (before that I will convert it from 2—wire to TTL (already ordered a power controller)
Meanwhile I have ordered also a new laser head (actually two - one TTL 5.5w and one hopefully more powerful)

Just checked the power supply rating - it's 10A actually. I do have a bench power supply - but I'm waiting for the new stuff to arrive. Then I will be able to compare.

BTW for how long did you use your 5.5w head before it started to fail?

[ggallant571]

I think the 5.5W lasted for about 18 months of light usage. It was good for etching slate which started my addiction.

BTW - I don't think there is a considerable difference between 2 and 3 wire modules, especially for cutting. Both take a TTL control signal and convert to a constant current source. Some of the 2-wire modules have a large capacitor (user removable) that limit the diode ON/OFF response. Might negatively effect very short burns but would only delay the start on stop times for longer burns.  The 3-wire just moves the high power switching circuit closer to the diode. Definitely a better electronics design and probably cheaper to manufacture.

The ability to burn is dependent on the energy per unit area. Cutting the radius of the focal point in half reduces the burn area by a factor 4.  The diodes and optics are sorted by quality and the "good" go to industrial applications, the average to to "quality" vendors, and the rest go to Chinese EBay.

My 5.5W laser has a rectangular beam pattern. The ratio is about 5 times long to narrow. When cutting rectangular patterns, I adjust the focus so that the beam is at 45 degrees to give a more consistent X/Y kerf. When etching I adjust it to be vertical and sometimes compensate in the artwork.

[toromand]

Just a quick update - I replaced the old laser with the new one and it cuts again, as expected. (both 5.5w)
Meanwhile I just used several more passes for cutting. The old head will be stored as a spare.

BTW. I notice some faint laser light "leak" to the side of the 'dot" on high power even the beam is focused. Are there some better lenses to fix that and should I even bother... (I guess the amount of the energy lost is very small)

[Zax]

There are replacement lenses but a few years ago I tested several and found the difference was negligible, it's been a while but I think it was the G2 that performed slightly better. I tested with a 2.5W for engraving so the 5.5W may perform differently.

[toromand]

There are replacement lenses but a few years ago I tested several and found the difference was negligible, it's been a while but I think it was the G2 that performed slightly better. I tested with a 2.5W for engraving so the 5.5W may perform differently.

Yes, I have something like 3-4 lenses myself performing quite similarly. I was just wondering about the "lost" energy leakage - but I guess because of the square beam.

[Zax]

That's why I prefer the 2500mW for engraving, the spot is round and 1/4 the size so power density is actually higher than you would expect although the 5500mW still has the advantage for cutting.

[ggallant571]

I had better cutting results with the 5.5W when I raised it up 10cm.