Reduced power for a 60W laser machine

Hi all,

I have recently been having problems with my 60W Chinese laser cutter i had it for about 3 months and the tube went which i replaced however since then i have had to reduce the speed and power levels to be able to cut.
I have re aligned the mirrors about 3-4 times trying to rectify the problem but it just seems to be getting worse.
I can engrave with no problems but when i try to cut through the material (3mm MDF) the laser struggles even at slow speeds.

The other thing i have noticed if i raise the power level to above 40% the laser fires but the laser only appears out of the nosle for a short time then disappears.

If anyone can think of why the laser would be doing this please let me know its driving me crazy.

The thaught i currently have is that there is something wrong with the lens / mirrors as this is the only thing between the laser tube and the materials

Thanks in advance for any help
Dave :)

What is the power supply outputting vs what the laser can handle? Even though (and partly because) you are running at on 40% power you might have a too powerful power supply and be overpowering the tube, which I hear shortens life dramatically. Do you have a meter hooked up?

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Hi,

I dont have a meter hooked up and have no idea what the laser is out putting all i know is i used to cut 3mm mdf @ 10mm/s @ 45% power and now it wont even cut @ 3mm/s @ 30% power
and is i try more than 40% power the laser tube fires but nothing comes out of the nosle

Thanks
Dave

Well the fact that you are that only at 40% as opposed to say 80% suggests you have a more powerful power supply than you should.

So without a meter it's hard to say what caused the issue but if you consumed the first tube in 3 months, and the second seems to be failing fast too I think your cooking it with too much juice.

The remedy will likely be another tube but I'd order a meter too.



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Hi,

I dont understand how you can say its getting to much power what are the normal setting i.e cut speed and power for a 60W laser to cut 3mm MDF??
also the origonal tube was faulty thats why it went so fast running the power @80% for a 60W laser just to cut 3mm thick MDF sounds rediculas.

Is there any way to check the other components ie mirrors lens etc as the laser isnt showing any signs of being damaged no cracks water flows great no air bubbles the last tube was arcing really bad before failing

Thanks
Dave

Ahh OK. Until you said it was arcing I had no idea what caused the first tube to go. I don't know what normal settings are but generally I run mine at one power setting and vary the speed for the material and thickness (unless engraving).

Still, you should have a meter as I think I shortened the life of my first tube because I didn't.

You can certainly align but it sounds like you have. You can try replacing the mirrors as that can do it too if scratched, that helped me one time.

Otherwise it's down to results. You can buy laser power meters but the price might not be worth the answer.



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Hi,

Anyone else got any ideas what could be wrong??

Thanks
Dave :)

Power supply. Control voltage to power supply. Power supply is most easily checked by swapping it with a spare, the control voltage is checked by identifying the wire that sends a full 5v signal (or close) and the wire that sends a signal 40% of the full signal telling the power supply to fire at 40%,.




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Hi,

Unfortunately im completely new to laser cutting and dont have any additional equipment or spares is there anything else i could test first as the power supply seems to be running the same as it has for the past 8 months.

Thanks
Dave :)

OK.

Here's where I would start:

1) get a multimeter and hook it up to the return wire on the laser tube (the side from the tip/output side to the power supply - usually black). Measure the Milliamps. Compare that to what your laser tube is rated for. You may need to have the laser actually firing at the lower power to read it.

2) Use the same multimeter to find and connect to the control voltage and then to read the trigger voltage (you can disconnect both and just read the voltages without the laser actually firing).

on the first one, you hopefully have readings that make sense for your tube but if not it might be time to buy a spare power supply. The spare serves 2 purposes 1) its not a spare if it solves the issue and 2) it is a spare which will help you diagnose and repair future outages. Its also cheaper that an new tube and has an indefinite shelf life so it makes a better spare to have than a tube if you are not in a production environment (in which case a full set of spares can be a good investment).

For the second one, its just a math calculation to make sure the ratio of current is right. If it is, the controller can be eliminated as a source (it rarely is).

At the same time and from the same vendor, maybe pick up some mirrors but I really think that if the tube has stopped firing at a higher percentage then its toast but you might want to use the last gasps to determine why it is toast so quick. Mine exhibited similar issues near the end of the first tube. When the gas is nice and cool it would fire a bit but then the laser basically warmed up the gas and it went downhill. I solved it with another tube (after doing all the checks I mention but I had the power supply available).