I've sometimes found motors vibrate when one of the coils is back to front.
eg: Say your wires are the following:
Red, Green, Blue, Yellow.
You may find that switching the Red/Green may improve things, or switching the Blue/Yellow.
Note: This will switch the direction the motors spin, so you need to compensate for that in firmware.
If it's not that, then it looks like you might have some bad motors. I've also had similar things happen if the motor shaft bearings get damaged (eg: the motor gets accidentally dropped on the drive shaft, if you've put a flat on the shaft yourself and not protected the bearings from metal dust, etc), where it then runs quite rough and vibrates.
Unless you feel really confident opening a stepper motor and changing the bearing over, which is not really a simple task, then replacement is the only option.
PS: If motors aren't packed right, so that they can't move and can't be dropped on their shafts, this sort of damage can happen in transit. No one in the postal/shipping services cares what's in your box, and they can't be expected to know either. Packing motors properly is one of the things I see a lot of suppliers fail at, as they don't expect the postal/shipping services to be as brutal as they can be, nor to they think that things like stepper motors can be so fragile as they can be.
eg: Say your wires are the following:
Red, Green, Blue, Yellow.
You may find that switching the Red/Green may improve things, or switching the Blue/Yellow.
Note: This will switch the direction the motors spin, so you need to compensate for that in firmware.
If it's not that, then it looks like you might have some bad motors. I've also had similar things happen if the motor shaft bearings get damaged (eg: the motor gets accidentally dropped on the drive shaft, if you've put a flat on the shaft yourself and not protected the bearings from metal dust, etc), where it then runs quite rough and vibrates.
Unless you feel really confident opening a stepper motor and changing the bearing over, which is not really a simple task, then replacement is the only option.
PS: If motors aren't packed right, so that they can't move and can't be dropped on their shafts, this sort of damage can happen in transit. No one in the postal/shipping services cares what's in your box, and they can't be expected to know either. Packing motors properly is one of the things I see a lot of suppliers fail at, as they don't expect the postal/shipping services to be as brutal as they can be, nor to they think that things like stepper motors can be so fragile as they can be.