Min Max Power settings help please

TLDR: For my 60w laser - if I set max and Min power at 60% & 12% in VENDOR settings and WRITE it - do I run lightburn at 100%? (if I want a deep cut)

I’m back lasering after a few years absence and have recently got a 80w (prob 60W) Blue/Black SDKEHUI off ebay which at first glance looks very good.
Ruida controller which looks a lot more advanced than my previous one.

It doesn’t have an ammeter so I want to be careful that I don’t max the tube out as …surprisingly…it works very well. My last Red/Black (60w -50w) 6 years ago needed swapping immediately

I’ll be fitting an ammeter fairly soon but until then I want to practice and use the machine.

I’ve searched through the forum and the answers I see are just not clear enough - for me.

So…For my 60w laser - if I set Max and Min power at 60% & 12% in VENDOR settings and WRITE it - do I the run lightburn at 100%? (if I want a deep cut)

You can make a pretty good estimate of the tube power by it’s physical size. This table is very close. It should give you a maximum working current.

If you mean here …

If you set these min/max values, then this will limit the generated pwm/analog power control to be limited within this range… can’t go lower than minimum nor higher than maximum.

On my 6442g, if I set it to 20 minimum and 60 maximum, any layer in between these values will be applied to the controller…

@NicholasL advises his set limits the outputs but that the power percentage is the values between those limits.

You’d have to measure the output of the controller (or input to the lps) to determine which way yours works… If it worked how Nicholas advises, then it would sure complicate technical setups.

Install a mA meter… :+1:

Good luck :smile_cat:

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Yes, use the full range in LightBurn cut settings: 0 to 100%. But you should first use an ammeter to ensure that when you run LightBurn at 100% in the cut settings, that you do not exceed 18mA at the 60W tube.

When you first start to test this, it’s important (for the health of the tube) to start at low power % and work your way up. One way to do this is first check if you are reading roughly 9mA on the ammeter while at 50% LightBurn power, and then slowly add to the 50% power in 10% increments while observing the ammeter at each step (and reduce the vendor Max setting if necessary), until you make your way up to 100% at 18mA.

I think Jack may have an older firmware on his controller if going above 60% in LightBurn cut settings makes no difference when the vendor max setting is 60%.

Normally the 60% in LightBurn’s cut setting is equivalent to 60% of the 60% vendor cap, or more precisely - 60% of the range between the vendor settings, ‘Laser 1 minimum power %’ and ‘Laser 1 maximum power %’ .

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Having fixed lots of similar equipment, it would be a good way to get a technician into trouble and cost the customer a tube or at least too much current.

I know on mine, the mix/max at the laser settings, will limit the pwm output, just as the max settings for any other settings will limit that maximum. If it wasn’t limited by the maximum settings, what is it used for?

If you reads the pwm voltage he can check this very easily… Which is what I suggested, if yours operates one way and mine anything, that wouldn’t be good…

I have a 6442 and I think Nicholas has a 6445?

I have this haunting feeling that I’m misinterpreting your information… :thinking:

They run the 40W (supposedly) K40 at 18mA, so I’m sure a real 60W will take the 22mA suggested in the chart.


Thanks Jack and Nicholas
I fitted the Ma meter tonight and have a much better understanding now.
I’ll do full tests tomorrow as suggested but I couldn’t wait and wanted to see what
it would take to get to 21mA
Max I went to was 65% on a pulse and that fired at 21mA
More tests tomorrow to confirm

Happy chappy here - slicing through 10mm mdf like it was butter at 20mA

Oh I should say that the seller didn’t lie - it’s a 80w Yongli R3
1250mm x 80mm - and I looked up max working mA to be 21mA

Thanks for your help and suggestions all.

Now you need to adjust the lps for 50% of 21mA with when driven with a 50% pwm or percent power.

Crank the mA of the lps down until you read the 50% power point, then the lps will be synchronized with the output power… In this case, 100% would be your 21mA…

Make sense?

The lps has a 20 turn pot in it to adjust the maximum output current. With mine, you have to be a contortionist to adjust it…

Glad you have it up … aren’t you glad you put the mA meter in?


Yes - I was a bit nervous as the mA meter didn’t have pos or neg indicators (and I don’t have much knowledge about electrics)
But I seem to remember from last laser someone said in one of the forums that if you do it wrong it won’t harm it - just won’t work. But I still studied a few videos to see how others wired up - anyway all appears fine at first attempt

No idea what “lps” is - presumably something power supply? and if I can get to it - arthritis may hinder that - how do I “read the 50% power point”

I even made a chunky little box for it courtesy of boxes.py


Looks good. Did you guess correctly on the wiring?

Mine was pretty plain Jane when I got it… Added meters on my console…

LPS (laser power supply) – distinguish it from a lower voltage supply

If you want a 21mA maximum current, 50% of that is 10.5mA… twist the pot until it reads 10.5mA on your meter… You can set the Ruida to 50% power and continuous, then it will lase for as long as you hold it down… You just need to lase it long enough for the needle to stabilize… it’s relatively quick.

The 50% value makes it easy to calculate the meter value…

Make sense?


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ah yes thanks - the penny has dropped
I shall be looking at that today.

Yes…I got lucky :slight_smile: Well I did look at about 5 videos to the point where they turn it round so I could fathom out which way to go. I thought it would be that way but needed to double check

I did the same box on my old K40 and put some magnets in the bottom to hold it in place.

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