K40 Power Settings

Machine: K40

Board: Cohesion LaserBoard

Firmware: _Smoothie

Problem/ Question: So I tried this last night for the first time. My question is what do you set the power settings to on the original control panel (I have a digital one). I tried setting it to 90 on the k40 but it seemed to produce less power then when I set it lower. (Plastic didn’t cut all the way through)

I want to set the K40 and forget it. I want to just adjust the power from Lightburn.

Without knowing the exact current your unit is sending to the tube, it is impossible to give an exact answer. You should invest in a mA meter.

15mA is a general setting to leave it. Since all the digital control panels do not perform the same, I wouldn’t go above 60% until you know for sure. The reason it was worse at 90% is most likely due to overdriving it. After it reaches its best performance, it will start to degrade when you go higher and aren’t using super chilled water, plus it kills your tube either way.

You just need to know what it’s doing, which is why those “pretty” digital models are not recommended over the ones with the dial. It’s more appealing in appearance, but that’s where things end.

Cohesion3D sells these meters and there is informative installation instructions online.

Thanks for the info. I just ordered one.

All that info makes total sense.

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If your laser is firing and you have power set to 90% it should be cutting. To me this sounds like an issue of mirror alignment and/or lens/mirrors dirty. The brackets that hold the mirrors are not that substantial and potentially can move and twist with the machine housing. I would go through and realign the mirrors and inspect them for damage and/or dirt and try again at a much lower power at first.

This is a full comprehensive video on mirror alignment of the K40. It is an hour long but well with the watch. Aligning the mirrors is not just about adjusting the screws on the mirror brackets as you will see. After I watched this video, I took a go at a realignment and my laser was performing 100% better immediately. My first cut was an easy clean cut through 5/16 pine carside.

The other thing to understand is how to do a ramp test to determine your focal point and making sure you are very close with your workpiece. I usually shoot for the focal point to be halfway through the workpiece and it has done well for me.

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