K40 Whisperer now having power control is a big deal. While it was ok making a design and stopping between operations to adjust the power setting it took changing out not only the controller board but also the software tool for the smoother workflow. Now that K40 Whisperer has power control vi the M3 boards many now ship with the horn should be tooted.
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I still need a couple more people to try it before I get comfortable. I am also working on instructions for rewiring a machine to utilize the power control capability.
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If I run across an M3 controller I’ll give it a test and if I see anyone post with a new K40 having the M3 and ask to test.
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Hi everyone, this is actually my first post here and also my first experience with a K40 laser, so I’m still very new to all of this.
I’m using a K40 with an M3 Nano board, and just wanted to share a quick note in case it helps: with the laser’s power knob set to max and K40 Whisperer set to power level “1” (which I believe is the max in the software), my machine reaches around 9mA.
Before the recent update, even with the knob at max, I was only getting about 2mA, so this is definitely a noticeable improvement.
I don’t have an analog ammeter installed — I’m reading the mA values from the digital ZYE laser panel.
Happy to share more info if needed. Still learning as I go, but a big thank you for the K40 Whisperer release — I had to rely on LaserDRW before just to test the machine I got off eBay, and that came with all kinds of virus/blocked warnings. So this update is really appreciated!
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@Normal Thanks for the info, I am not familiar with that machine. In the K40 Whisperer “General Settings” there is a setting for “Max Power” if you increase that setting your max output should increase. The idea is to set the max power setting to the maximum you want the engraver to ever use (safe limit to not damage the tube) Then fine tune for each job with the power fraction.
My best guess is that the knob on your machine is intended to perform the function of the K40 Whisperer max power setting. So if you set the max power to a high value, you could use the knob to adjust the highest power level.
I put out a blog post with the information covered in this thread and some additional info on power control on the M3 Nano with K40 Whisperer.
Blog Post: Laser Power Control in K40 Whisperer with a M3 Nano Controller Board
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Thanks for the explanation — that really helped!
I changed the Max Power setting in K40 Whisperer to 100%, and set the power knob on my machine to around 15mA (which I consider my safe limit). Now it works like a charm — with the software set to “1”, it reaches exactly 15mA, just as expected.
I’m planning to test different power levels next, like 0.1, 0.2, 0.3, etc., to see what mA values they correspond to. I did a quick test cut, but it barely marked the surface. I spent quite some time re-checking the alignment, thinking that might be the issue — but now I’m wondering if the problem could actually be my 12mm lens.
I also experimented with different focus lengths — around 50.8mm, give or take — but still couldn’t cut through MDF or plywood(3mm), even with 4–5 passes and no air assist. So I’m trying to figure out whether it’s an alignment issue, the lens, or just the lack of air assist.
Oh well, I’ll get there eventually — thanks again!
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Note that the digital power meters normally are really just measuring the duty cycle, not actual power; this is why to protect tubes we do recommend adding an analog ammeter that will tell you true current through the tube. Not expensive, and not difficult. 
Also, please consider starting a new thread in Lasers if you want help working through the other issues, like lens choice and focus. Plenty of folks here happy to help out with other concerns too!
@mcdanlj The digital display on this ZYE machine is showing mA. This is not the same as a the machines with digital power control. I think this is displaying the current just like an analog ammeter would. @Normal said with 30% duty cycle (the default value in K40 Whisperer) the digital ammeter was displaying 9mA. The mA for 30% duty cycle listed on the table on @donkjr 's blog is 9.2mA.
Reference link to Don’s blog:
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I was unaware that the ZYE MYJG remote displays showed accurate power. Awesome! Thank you for the correction!
@mcdanlj I really appreciate the info!
I’ve been reading through the forum more and more lately, and slowly improving my machine as I follow all the helpful posts here. If I ever get stuck, I won’t hesitate to start a new thread.
I had read about the analog ammeter before, and like @Scorch mentioned, I feel lucky because my ZYE panel seems to give a fairly accurate mA reading. Still, I might add an analog one just for extra peace of mind.
Thanks again for maintaining such a helpful and welcoming community!
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