I seem to have found a strange firmware limit in my OMtech 100W (USB1006c) laser. I was doing some materials tests with a file I had created in Lightburn 1.7 using the Shape Properties to set different power percentages for each speed setting. All went just as expected with the engraving tests, but something really weird happened with the cut tests. Basically I discovered that setting a speed of 8mm/s or lower caused the laser to limit the power, rather than use the power setting I had chosen - so the slower test shapes did not cut through, even though the ones with faster speeds did. I then did a test which was just a small box with power set in the usual way instead of using the Shape Properties and again, if the speed was 8mm/s or lower, the thing did not cut through at the same power setting as a cut that worked at 15mm/s. On further investigation I found a “start speed” setting in the controller firmware that was set to 8mm/s and wondered if this was what was limiting the power on slower cuts? Presumably this is a safety feature to try and prevent fires? However, I’ve often seen people talking about cutting at speeds slower than 8mm/s and wondered if they have had to change this in their controllers to make it work? I currently don’t actually need to cut this slow as I’m only using 3mm ply, but I was testing to find the best cut settings that create the least overburn to try and minimise the amount of sanding required after cutting.
As you note, that’s lower than the Start Speed for at least one of the axes. You can lower it as you see fit.
Some earlier discussions:
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Thanks for that info which confirmed what I had assumed - and for the useful graph in the earlier threads. I wasted a good couple of hours today trying to work out what was wrong with my Lightburn file and it was only by chance I went and looked at the Machine Settings in Lightburn and noticed the two Start Speeds were set to the very speed that was causing the problem!
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