Hi

Just to tag this into the "encyclopedia" ..... it's a great thread for anybody playing with an i3v.

The issue with the "old hot motors" was aggravated by the recommended settings being to high current. I pointed that out 3 years ago, it's still true today.

These printers slave two Z motors to one controller. That limits you to 1/2 the current rating of the controller on the Z axis. Most of the standard controller plugins max out at 2A. If you buy 2A motors you will only be able to run them at "half power" on the Z axis. With 1.5A motors you will get to 2/3 power. All that assumes you carefully adjust the trim pots on the controllers when you swap out the motors. My *guess* is that roughly 99% of the i3's out there (with slaved Z motors) are running half current on the Z relative to the X and Y.

All that said, yes, the old motors do get hot. Having plywood all around them or a heated bed over them ... they get warm.

Some Z axis math (not in my older post):

Most of time the Z does not move. It's just a load resistor. P = I^2 * R. Cut the current equally between two steppers and you cut the heat going into them by a factor of 4. Yes, they still get a bit warm. If you take a look at torque curves ... that drops off by quite a bit as current drops.

So why the "old recommendation for current" ?

If you set the current limits all the same and to ~ 0.2V, the X and Y work. The Z fails horribly. If you set it high with those motors, the 12V limits the current as a bit over max ... it all works, but gets hot. They *are* 0.5A steppers, the right setting on the controller is the 0.5A setting.

Yes, this is 3d printer archeology. It is mainly interesting to those with i3's that they might be upgrading to say an i3v. Unfortunately some *idiot* pointed out that the $50 rebate was still in place on the i3 -> i3v kit. It seems to now be history .... SORRY !!!!! That may make this information a bit less useful.

Bob