You will have to check all your connections, disconnect any endstops, put the tool in the middle of your machine and try turning the machine and Lightburn on. These have to be properly adjusted for power.

I have DRV8825 Stepper drivers plugged into ti. I have Lightburn running right now on an Arduino Mega 2560 with a RAMPS 1.4 card plugged into it. I am wondering is this is just to help scale the image to the object and the 360 is defaulted? Is this a true use of the 4th axis? Are A commands to GCode properly created?

It looks like Lightburn will handle this properly as a 360 degree movement device although in setup when I select A axis the 360 is greyed out and the settings is still looking for object diameter and/or circumference. It looks like the prior GCode I created with Lightburn is moving things properly.

At any rate the piece moves accurately with G1 A_ F_ where A is in degrees. Using the Mega 2560 board, I have set up the A axis in GRBL under $133 and $134 and calculated the proper number of steps for my regular stepper direct driving my 4th axis - 200 steps, 32 microsteps divided by 360 degrees results in a ‘number’ for A of 17.778 steps (per degree I think). I would tell Lightburn to use Y as the rotary for example. In the past I had some success mapping a curved surface and burning to that with a ‘fake’ 4th axis using one of my Uno linear axes as a rotary axis. It can easily be loaded with Arduino IDE or with the Hex file and XLoader. It is version 1.1L and is intended for true 4th (and 5th and 6th) axis movements. I have just started to use Lightburn with a newer version of GRBL intended for the Mega 2560 board plus or minus the RAMPS shield.

Lightburn arduino