I am using a Grbl shield on a ShapeOko2. There is a high pitched humming noise and the motors stall out if I try to move too far at a time. Could it be that the pots need adjustment or do I need to set some max acceleration setting in the firmware of the arduino?
Sounds to me like a stall. When I first assembled my shapeoko I didn’t get the frame square enough or the tension right on the v wheels and it would stall out even at fairly low speeds and with max current to the steppers.
I ended up resquareing the frame and fixing it down to the table. Try running the gantry around by hand without the belts on and check the movement feels smooth, the same level of force required to move it around all over the bed. I gradually tightened the vwheels too. When you have it moving by hand smooth and the vwheels tight enough for minimal flex of the carriage on the rail then hopefully you can start making longer movements and increasing max speeds. I only managed to get to max speed of 10,000mm/min but that’s fast enough with a max jerk of 5000M. I am using a TinyG though so its acceleration max might be different from grbl shield.
I reckon your motors stall above a certain speed. Not sure you are already at the current limit, if not, rise it to the max possible. But your max speed is always going to be limited.
The motors seem to move stuff just fine at slower speeds and distances.
I will try tweaking the pots after in around 17 hours.
Like Miguel says, it sounds like your speed setting is too high. You’re describing typical behavior of a stepper motor if you’re trying to get it to travel too quickly. I haven’t used GRBL so I can’t really give you proper settings, but I get the same issue on an entirely different electronics setup if my speed settings are too high for the motors.
@Jamie_Wilburn its not as simple as a speed setting too high for the motors, its a combination of the friction in the bearing setup (v-wheel tightness, squareness of frame etc), the current setting on the stepper drivers and the speed and acceleration settings.
This is why when I had this issue I went back to moving by hand without belts first, taking the current, speed and acceleration settings out of the equation. Ensuring I had smooth movement across the entire area first (solving v-wheel and squareness issues), then I moved to setting current to about midway for my drivers (just a guess), then gradually bringing speed and accelerations up until slipping and stalls started to occur on full length moves. A little back and forth on current and max speeds then gave me the sweet spot.
When you move the gantry by hand, unplug the motor wire from the shield. The electronic might fry with the generated current.
@Dat_Chu Interesting. Luckily, I did not fry it yet.
I suppose my Z could be a bit easier to turn by hand. There is some resistance. I do not feel like taking that pain in the butt apart again though. 