Laser power output varying with engraving head speed

I have an OMTech MF-1624 laser with a Ruida 6442 controller running on a MacBook Pro using the most current release of Lightburn. Today, I noticed that when I increase the travel speed for the laser head, the power output of the laser power supply drops. For instance, I can use the settings of 35mm/sec at a power setting in Lightburn of 40% and the laser power supply outputs 8mA. I can up the speed of the cut to 60 mm/sec and keep the power at 40% and the laser power supply shows 10mA now. I can lower the speed setting to 15 mm/sec at the same power of 40% and the laser power supply shows 3mA. It hasn’t been doing this until this afternoon. The machine is only about 2 weeks old and I’m new to lasers. Any advise or help would be appreciated.
Thanks in advance.

If you are looking at the digital meter on the supply its pretty much only good when the laser is on continuously. It ‘samples’ so no telling when it looks and the laser is actually firing.

Don’t think this applies, but you should know about it.

What do you have set for Min and Max power on the layer?

There is also a setting in the controller configuration that is ‘Start Speed’. If you run below that speed it will only produce the Min value power.

If in doubt you can set them the same for testing purposes. It’s used to vary the power levels as the laser slows to make corners. Generally only during vectors does this come into play.


Thanks for the response!
Yeah, I knew that the power supply only showed amperage when the laser was firing. I have the min and max set, in this example, at 10% min and the max was 55% if I remember correctly.
I will check the “Start Speed” after work. I’ve not heard of that yet and I may have accidently changed it or something. I understand what you’re saying about running the laser speed too slow and that may be the issue. I’ll check that and report back.

Thanks again for the info!

Don’t know if the ‘Start Speed’ is your issue, but you should know about it.

The controller creates a ‘power’ curve between Minimum power and Maximum power based on speed. Start speed is where Minimum power starts. If your job runs at or below the start speed, it will never apply anything more than Minimum power.

Make sense…?

This pretty much applies to vector cuts as scanning has room to slow down, turn around and speed back up.


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Yes! that makes perfect sense! You are quickly becoming my favorite member. LOL
I’ll take a look at that when I get home from work and see if that may be the issue.
Thank you again for your wisdom!

I’ll report my findings asap.

Most of the time here, it’s to get peoples brain engaged and knowledge is the key to that…

Take care, good luck :slight_smile:


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You are the man! You were 100% correct in your assessment. I upped the speed and kept the power output at the same and it sliced like a hot knife through butter. Thank you for your help and I’m glad you are here.

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No perspiration. Good luck and have fun…

Make this solved if that’s the case…

Take care


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already did!

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