We installed and focused the mirrors and lenses today. I adjusted the current out of the high voltage power supply to match our new EFR F4 tube. Before leaving we did a hive13 test card after focusing the lens and adjusting Z axis height.
We’re not quite ready to declare the laser ‘open’. Still some more things to do.
Also, it is MUCH more powerful than it has ever been (it can cut a 2x4 on 50%). Our new tube is greatly more efficient, mirrors are better, lens, etc. So, there will be new guidelines on usage, settings, etc.
Ooooo I’m seeing woodblocks!
So you are talking 50% power to cut through an inch and a half of wood? Now I’m curious if it can cut 1/2” Baltic Birch. I know it has to cut through the glue but seems possible.
the glue may smoke a lot, and we just got clean mirrors ! maybe we can bump up the compressor air a little to help keep the optics clear?
There’s a 2X6 we lasered a few times testing. We also lasered an inch-thick piece of plywood at a slow speed, then I cut it in half with the bandsaw to see the cut. If someone reminds me tomorrow when I’m there, I’ll cut the 2X6 in half so we can examine the cut.
There’s a piece of that grey plastic we lasered at what ended up being like 40% power and it sort of annihilated it. In short, the new tube’s damned powerful.
What mA Max should we look for, or does the power supply adjustment prevent overpowering the laser?
With the new power supply settings 25 ma should be peak output. None the less, keep an eye on power levels as your cuts progress.
Be wary of full power cuts. This tube is powerful. The optics are clean and well aligned. 100% power is much more than before. Run material tests and adjust accordingly.
That said. The laser isn't quite open yet. Operator checklists need update. See you all this evening for a demo.
This tube should not exceed 28ma. I adjusted the high voltage power supply to limit it at 25mA, which is the ideal maximum for this EFR tube. I set it with the oscilloscope and my Agilent mA current probe to ensure the actual power of the pulse correlates. So, at 100% power, the current should not exceed ~25mA RMS. However:
- Everyone must check the meter periodically during use (at least once with small jobs). Even though the power supply is set and matched properly, it is there for a reason. There are factors which could cause the current through the tube to rise or to drop irregularly. It is everyone’s responsibility to verify that the current is acceptable every time – if it is not, that means something is wrong. If the meter indicates that current is too low or too high or tweaky, stop using the laser so the issue can be fixed / adjusted.
This tube & the much nicer mirrors and lens are more efficient than the previous tube. It produces much more optical power at lower current than the previous tube, and also starts at low current / power. So, the ammeter may read as low as 1-2 mA during light engraving. Previously this was not possible.
Finally, don’t jump to conclusions about cutting 1/2"+ ply yet. Just because it can doesn’t mean it does it well. This is a photo of what Greg’s 100% at speed 1 cut in 3/4" plywood looked like afterward!
Mmm… That ember kept going for minutes afterward. S’mores anyone?
Of course that cut was done before adjusting the focal distance of Z height.
I will put together operator instructions & checklists. Be patient, we’re still testing right now.
Certified users will need to learn new procedures and protocols, which I will put together. Put simply, if someone used the same settings they used on the previous setup to cut acrylic now, there is a very real possibility of a serious fire producing very noxious, harmful fumes (even with the exhaust and blower in perfect operation).
Also, the reflected light from the laser is MUCH brighter than before. Even in normal operation, your eyes will be damaged if you look directly at the focal point. Two pair of ANSI certified Honeywell CO2 laser protection glasses are now here. Use them. I do not trust the G Weike glass to block both intense IR and the broad spectrum light produced by combustion of various materials. I actually felt a minor “flash” from looking at one of these test cuts through the laser’s glass. The new goggles have broad spectrum protection, but still, don’t stare directly at the beam. I’m serious.
PS If anyone has an optical power meter, let me know. It might be fun to see what wavelengths and intensities are present from the reflected light. And, of course, if someone has access to a laser power meter that would be cool too.