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  1. #1
    Join Date
    Apr 2019
    Posts
    4

    K40 - Digital Power Meter

    I should have read the forums better but I purchased a K40 that came with a digital percentage-based power control. That is, you set the power for the laser from 0 to 100%. The laser doesn't lase below 9% and I've been scared to turn it up much past this. So far I'm only cutting cardboard. I have two questions.

    1. Does anyone have a similar setup and mapped percentages to actual power. (I wouldn't assume it's the same as mine but it's a start.)

    2. I'm guessing an analog 30ma ammeter from amazon(https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1) would not be suitable. I suspect the high voltages demand something a bit more specialized. I have the "Green" power supply version (with the Phoenix terminal block). Does anyone have a recommendation for a suitable ammeter? Are these hooked up inline with the tube or some special output from the power supply?

    Thanks,

  2. #2
    Join Date
    Apr 2019
    Posts
    4
    I think I have found the answer to my question. It appears that the cheaper ammeters will work if they are installed in series with the ground side of the tube. I guess the resistance of the tube lowers the voltage drop across the meter and lowers the danger of an arc. I'm still interested to any answers to question 1.

  3. #3
    Join Date
    Apr 2019
    Posts
    1

    Re: K40 - Digital Power Meter

    Quote Originally Posted by sjernigan View Post
    I think I have found the answer to my question. It appears that the cheaper ammeters will work if they are installed in series with the ground side of the tube. I guess the resistance of the tube lowers the voltage drop across the meter and lowers the danger of an arc. I'm still interested to any answers to question 1.
    as far as i know, k40 laser machine from china ussualy set 99.99% power to about 15mA. this is to protect tube. i ussually cut acrylic 3mm with 30% of power and cutting speed about 16mm/min. and dont forget to adjust distance between laser lens to media that will be cut.

  4. #4
    Join Date
    Apr 2019
    Posts
    4

    Re: K40 - Digital Power Meter

    I was able to get the ammeter installed but am kicking myself for not checking it with a known source ahead of installation. The shocking news is that my settings are WILDLY different than yours. They are:
    10% - 4ma
    20% - 9ma
    25% - 11ma
    30% - 13ma
    35% - 15ma
    40% - 17ma
    45% - 19ma
    I tested this by pressing the test laser button just long enough to take the reading. Thank you for the acrylic cutting reference. I plan to test the accuracy of the meter and will obtain some 3mm acrylic to test the cutting speed. One more question for you. What is the minimum % and ma your laser can be set to and still excite a beam?

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