I have recently finished building a laser engraver with a dedicated rotary axis. The engraver only has an X axis (liner movement) and a Y axis (rotation), there is no Z axis. The steps per unit have been calibrated but I have an issue with the X axis moving faster than the Y axis.
I have been using LightBurn to create g-code for the machines Marlin based controller. The Rotary Setup in LightBurn is enabled, and I have done a number of test burns, which have been successful, apart from the X axis moving at a different speed from the Y axis.
In Marlin, the rotary axis is set up as the Y axis - I’m wondering if this should be changed to the J axis? Also, max_feedrate and max_acceleration are the same for both axes.
Are there particular settings that I need to look at for the rotary axis?
Moving at a different speed shouldn’t be an issue. Moving at an incorrect steps per mm will need to be addressed, but the challenge with a rotary is that objects with a different radius/diameter are going to move a different surface distance (fraction of an inch or mm) per step. Generally, I’ve seen this addressed at the image design phase, getting the size right for the object it is going on to. Another option, used on my EggBot (which prints on cylinders and spheres with pens), is to create a template with the number of horizontal pixels equal to the number of microsteps in one revolution. This will automatically scale to any size object, but it means designing in bitmaps rather than using vectors.
@ttraband Thanks for taking the time to reply to my post. It was the steps_per_unit that was causing the issue.
Because the Y axis on the machine is a dedicated rotary axis, I originally set the Y steps to 22.2222 and the mm per rotation (in LightBurn) to 360. This made the travel distance spot on, but threw out the travel speeds.
I ended up changing the Y steps from 22.222 to 80, which is now the same as the X steps, and calculating a new value for the mm per rotation in LightBurn. Now everything is running as expected.