Laser overheating?

LightBurn Software Questions OS Specific
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1

USING A MONPORT LASER 60WATT GALVO JPT
Windows 11
LightBurn 2.0.5 pro

I hope I am in the right place. I have a monport laser 60Watt Fiber, I do challenge coins in Brass. I have recently started doing 70mm coins and every time I start the project the laser stops at about 10-30%. I run a small USB 6" fan on the side of the machine and always blow cool air through it. My settings are these for a deep engrave.

2000 mm/sec
70 Hz.
.025 DPI 1254
80% power

I also run a cleaning pass every 25 passes

2000 mm.sec
80HZ
60% power
No cross hatch as I need a very clean base layer

Any ideas what I am experiencing here? The laser only has about 70 hours total on it and has been fine doing the 40mm coins?

2

Is it doing fine when you go back to the 40mm coins?

You have an external cooling fan blowing on it? What is the ambient temperature where it is operating?

3

Hi Mikey, and thank you for responding. I live in San Clemente, CA. by the beach. The unit is in my garage, and the temperature currently is about 78 deg F. outside. I prop up an ice pack next to vents and blow fan over the ice into teh vents. Yes, this happens with the 40mm coins as well, but this usually is when I am running several coins back to back. I assume it has something to do with heat. I have turned the machine off for about two hours and will try again, but I am confused.

I am wondering if it is something to do with the pulse rate? I have it set to 200ns; I was told .5ms which works out to a substantially longer dwell pulse time, but I am fairly new to this hobby but learning!

4

You must have a JPT MOPA, I have an M60 JPT M7 MOPA. All of your settings look legitimate and your ambient temperature is also reasonable.

Did you put these ‘added’ cooling items in after you found it was overheating? Usually these are find without external cooling, so I wonder why you need this?

I’m not sure what you mean by pulse rate, this is generally referred to as frequency, that determines pulse rate.

This is the output of mine, using q-pulse setting.

60W-fiber-pulse-graph
60W-fiber-pulse-graph893×429 93.3 KB

Frequency is more like sand paper, the lower the frequency the more rough is the results. There are only about 16 q-pulse settings.

:grinning_cat:

5

The laser source is most likely a JPT M7 60W E2.
At a pulse width of 200 ns, you should not exceed 48 kHz.
Reduce the pulse width to 100 ns if you want to maintain a frequency of 80 kHz.

6

Thank you. I will try this. I have a pulse rate and a frequency setting on my LightBurn software when I engrave.

7

I have two settings in my LightBurn settings when I am setting the speed, frequency, and pulse rate. I don’t really think I need pulse rate, as I thought this was for engraving on stainless or titanium for color changes. I usually use a mid-frequency of 55-60 when I am engraving and a freq of 80 when I am cleaning. I have just finished up another 40mm coin with no issues, so I am totally confused as to why, when I go to a larger engraving area, it shuts down?

8

Forgot to add, I did add teh fan and the ice packs when the machine began stopping short of finishing which I could only, as a newbie summize it was from heat build up. This began when I had an order for 50 coins back and front engraved.

9

Thanks to @jkwilborn and @PawelSekula for jumping in. They have machines I do not.

@jkwilborn is correct, 78° should not be a problem, but I believe it is in your case. Does your Fiber have a cooling fan in the cabinet? If not, with caution, you might remove a panel or two for better air flow.

I would also reach out to the manfacturer for advice.

10

What planet are you from? :wink:

These are pulse machines, so frequency or pulses/s are very critical for using them. When I did colors I used frequency and pulse width pretty much the most.

Fibers can also cause different types of damage, depending on if you scan over the area multiple times. If you spot size is 30 microns (0.030mm) and your interval is less than 0.030mm, you’re scanning the same area multiple times. We use this for color quite a bit.

I think @PawelSekula means is there is a threshold value where the machine will lower it’s output… this is from mine. It varies with the source you have, which you haven’t advised us of what it is.

Screenshot from 2026-08-26 14-57-40
Screenshot from 2026-08-26 14-57-40448×761 47.3 KB

What is shows is if I use a q-pulse width of 100ns, want available power, the frequency must be 90kHz or more.

The problem is, if it’s actually overheating, I think running it this way will produce more heat, which I think would exacerbate the issue of overheating.

I use whatever I need to make it work, but have used frequencies in the 1000lHz and up range for cleanup. My MOPA takes frequencies up to 4000kHz, although it starts at 1kHz, it’s in cw mode, not pulse as the chart clearly shows.

I suggest you contact your vendor and ask for help. They are your best chance. I’d get rid of the extras for cooling and ensure it’s getting good airflow internally. The reason behind this is that the source has it’s own fans, so you have to be specific where your coolant path is.

I suggest you contact your vendor and ask for help. They are your best chance. I’d get rid of the extras for cooling and ensure it’s getting good airflow internally. The reason behind this is that the source has it’s own fans, so you have to be specific where your coolant path is.

image
image230×262 38.4 KB

By not learning how these settings work, you’re shooting yourself in the foot. These are where a MOPA shines over a q-switch type and also what makes them a bit more complicated than a normal cw type laser.

Hang in there. It’s more like climbing up an an overhang than up a cliff, you’ll get it, just be patient and ask, if you’re not sure… or it isn’t working the way you think it should work.

:grinning_cat:

11

Are you sure, Jack?
I’m asking seriously, because in my opinion it should not be higher than 90 kHz in this case.

12

Why do you restrict the frequency you use? Above 90kHz shouldn’t be a problem?

If you have the same source with a q-pulse width set to 100, the minimum frequency you can use without the source limiting it’s output, is 90kHz.

If it’s a lower frequency than then your source could be restricting the available power levels. Higher frequencies won’t be an issue, it’s only frequencies below the threshold.

Most of these produce the highest power output at a lower frequency. My machine claims the 45kHz is where mine delivers the most power.

I’ve used mine for over three years, 99% of using one of these is learning how it works and what is kind of control is within it’s realm of possibilities.

Being a pulse laser, many things a different than a cw laser.

:grinning_cat:

13

Thank you for your reply, Jack.
It looks like I’ve been reading the table upside down for the past two years :wink:

14

Does the laser continue working and can you see the progress in LightBurn, but it just has no power, or does the job stop completely?
If it’s the first case, then it is almost certainly overheating.

I had similar problems when I first started using my laser. What helped was using a large fan (about 25 inches). The fan is positioned about 10 inches away from the laser housing.
This solution works for me.
As soon as I turn off the fan, the laser overheats after about an hour.

15

the laser stops the time bar keeps running but nothing.

16

the laser stops the time bar keeps running but nothing. I also have a small USB desk fan I place right on the right side intake, it blows through the electronics. I am going to dissasemble the top and see whats going on inside, see if any brass dust has made its way into teh components

17

Small USB fan does not provide enough cooling.
Try using a large fan – I’m almost sure it will help :slight_smile:

18

I could be your laser source has a bad fan. If this is relatively new, I’d check with the vendor. At you’re ambient temperature I wouldn’t expect any issues with overheating.

When it quits lasing, does the galvo mirrors keep moving?

If so, it sounds like a source issue. There are no easy ways to test these. Supposedly there is an rs232 connection that you can plug into the source. JPT apparently makes software to look at the source.

Good luck.

:grinning_cat:

19

Or an extractor in reverse position as a blower.

20

Will do ill let you know how it goes.