I'm struggling in the commissioning of my Mendel90-based printer with getting the x-axis consistantly parallel with the bed. Once I've manually turned each of the z-axis lead screws to get the hotend just kissing the bed, once I raise and then lower it a signifiant amount, say >50 mm, or home the z-axis, one side is off by a noticable amount. I'm guessing it's missing steps.
I'm using these steppers RAMPS 1.4 electronics, and pololu knockoffs that seem to be decently made. Initially I hooked them up in parallel as the RAMPS board has dual headers for the z-axis and it was the easiest...no rewiring of connectors needed. The pololu is set with a Vref of 1.2v (1.5 amps * 8 * 0.05 ohms * 2 steppers). Anything less than this and they just squeal and don't move. That results in my current situation of missing steps.
Seeing that it's recommended (both in nophead's build guide as well as other forum posts) to wire them in series to reduce the current requirements, I wired them up in series. Reducing the Vref down to .6v I can not get both of them to turn. Half the time they just squeal similar to when they were in parallel with a Vref < 1.2v. When they do turn, only one or the other turn but not both. If I give a slightly nudge to the couplers to help them turn, they'll turn maybe 1/4 or 1/2 turn then squeal some more. Adjusting the Vref +/- a few tenths fo a volt does not appear to help the situation.
What am I doing wrong? When in series they both turn the same way when they do decide to turn, and the fact that they both do move some would seem to indicate that they are wired correct (no wires crossed, mixed between coils, etc) right? I'd have to try again, but I think very small movements, like .1mm, worked, but that's less than the distance it would be just twitching while it squeals with the M6 lead screws.
Ultimately I don't care if they are ran parallel or series as long as they work reliablity and accurately.
I'm using these steppers RAMPS 1.4 electronics, and pololu knockoffs that seem to be decently made. Initially I hooked them up in parallel as the RAMPS board has dual headers for the z-axis and it was the easiest...no rewiring of connectors needed. The pololu is set with a Vref of 1.2v (1.5 amps * 8 * 0.05 ohms * 2 steppers). Anything less than this and they just squeal and don't move. That results in my current situation of missing steps.
Seeing that it's recommended (both in nophead's build guide as well as other forum posts) to wire them in series to reduce the current requirements, I wired them up in series. Reducing the Vref down to .6v I can not get both of them to turn. Half the time they just squeal similar to when they were in parallel with a Vref < 1.2v. When they do turn, only one or the other turn but not both. If I give a slightly nudge to the couplers to help them turn, they'll turn maybe 1/4 or 1/2 turn then squeal some more. Adjusting the Vref +/- a few tenths fo a volt does not appear to help the situation.
What am I doing wrong? When in series they both turn the same way when they do decide to turn, and the fact that they both do move some would seem to indicate that they are wired correct (no wires crossed, mixed between coils, etc) right? I'd have to try again, but I think very small movements, like .1mm, worked, but that's less than the distance it would be just twitching while it squeals with the M6 lead screws.
Ultimately I don't care if they are ran parallel or series as long as they work reliablity and accurately.