I’ve been fighting an annoying missed y-step problem ever since switching from the Melzi to the Elefu Ra driver board. It’s not the board - but the tuning of the potentiometer on the stepper driver (I think.) I put active cooling on my drivers (30mm fan), which helped a bit. It only occurs when doing rapid small reversals in direction in the y-axis, like filling in the wall of a circular/rectangular portion. I’ve turned infill speed down to 40mm/s with little change. I also have Acceleration control in slic3r turned on, with infill set to 46000mm/s^2 (and similar speeds for everything else.)
What am I missing? What contacts could I throw a pricey multimeter on to more precisely tune the set-point of the current limiter? The melzi @nop_head provides has the stepper drivers integrated onto the board, and I recall reading something about the way it was wired setting the current limit.
@Anthony_White do you really mean 46000mm/s^2? Not 4600? If you do have it set to 46 thousand that’s likely your problem. A ‘high’ value is usually 9000.
@Tim_Rastall how did i not catch that? oO
Accelerations over 9000 are typically only possible for lightweight bowden systems, although strong bots can get pretty close to that, at the expense of overswings at corners.
For once, the wiki is helpful here: http://reprap.org/wiki/Pololu_stepper_driver_board#Tuning_motor_current
The pot’s metal top (where you stick your screwdriver in) typically carries the ref voltage, making it an easy test point.
Maximum current will depend on how well the drivers are cooled as well as on other factors. I generally set it as high as possible while trying to keep the thermal shutdown from tripping.