I am making progress to turned wooden bowl embellishment. I built a simple, inexpensive rotary axis from a geared Nema17 stepper 5.18 : 1 ratio, an 8 mm shaft, a couple of bearings and a plain 1” bolt I drilled on my wood Lathe for the 8mm shaft. It was easier, as Ryan has said, to drop that part of the table than to have spindly legs for the MPCNC. Figuring the steps per mm that Lightburn requires was essential. Otherwise my 3 watt LED laser burns like a champ. The depth of focus is about 6mm so for now flatter parts of the curve work better. Eventually I will find or invent a way to have the LED laser follow the curve to maintain the focus. This is a test piece of birch on a standard 1” 8tpi chuck commonly used on wood lathes so I can turn it, burn it and finish it without rechucking. I’m running GRBL on an Arduino Uno for Lightburn rather than on my Rambo board since I’ve found it much easier and quicker to reprogram the GRBL parameters when I need to. The current GRBL version also has a useful laser mode. I simply plug the rotary axis into the Y stepper driver. To hold the Y axis steady I could plug the Y steppers into the A axis but with the laser it isn’t necessary. I can lay the rotary axis on it’s back to engrave a platter rim or base. I haven’t implemented the camera feature of Lightburn yet but that would make a lot of things very easy. I figure it is a simple, cheap, useful, and effective solution to do what I want for now.
Next step is engraving or piercing a bowl with the router but that will be on a stiffer CNC machine I’ve built, with a similar rotary axis and a little stronger NEMA23 stepper to resist the rotational forces. I’ll try that in a few days.