If you are using a old Windows machine that is “bricked” to run your C02 laser can I suggest that you update the motion control board on your laser to a board that is fully compatible with Mac and Linux as well as Windows. VMS Laser Accessories make the incredible LX4 board which is all singing and all dancing board but now have produced a smaller exact swap out board for the K40, its around 80 dollars and worth every penny, not only do you get your laser running in macOS you also increase the quality of your work and speed by using this board.
I use the LX4 as my laser has around a 1 square metre bed and I didn’t particularly want to go the Ruida route, the speed on my board is phenomenal with a 80 watt tube in it. It will run over 1000 mms second but the laser wont keep up with it and I need several hundred kilos to hold the Gantry down to prevent it leaving my workshop at those speeds.
I can recommend changing yours without any reservations, all you need to do is swap the cables out and put the new board it, no wiring, no headaches ever.
I would also like to add the best way in this forum to get help is always publish your Lightburn file and where you can post screenshots of what you are talking about. you will get a better result much more quickly.
There are some masters of Lightburn on here who will gladly help others.
regards
Neil.
