I’m using Lightburn to run a laser module attached to an X-Carve using the X-Controller (GRBL). I wasn’t getting the cutting results I expected at very low speeds (e.g., 5mm/min) so I decided to test the speed settings. When I set a simple move (either X or Y direction) of 10mm at 10mm/min I expected that to take 1 minute. Instead, the move was completed in ~13 seconds. I tested other, higher speeds and found that at or above 50mm/min, the speeds were correct. Below 50mm/min, speeds were off. For example, a 40mm move at 40mm/min took 53 seconds and a 20mm move at 20mm/min took 26 seconds. I’m familiar enough with GRBL to make changes to get distances correct, but I’ve never run into this kind of thing and not sure where to look. Any help will be appreciated!
Older comment related to Grbl 0.9 but might still apply 0.9i - Min feedrate appears to be around 40-45mm/min · Issue #742 · grbl/grbl
Wow...thanks for the link! A minimum feed rate of just under 50mm/min is exactly what I'm experiencing. I don't know enough to fully understand what the proposed solution is, but I'm investigate further.
also, you are ignoring acceleration time. The stepper motor cannot instantly 'go at set speed', it takes time to get up to speed, and at the other end it takes time to slow down and stop. so 1 meter at 1000mm/min will always take longer than a minute.
