I've had a curious issue with the E3D Super Whopper motor so I thought I might share it to see if anyone else had a similar experience.
First I got one brand new (never used) from my friend @arhi and tried to replace my Y bed stepper just to see how it would perform. I set the steps properly (it's a 1.8-degree stepper, unlike other E3D steppers) and the current to around 1.8amps (it's rated 2amps). The belt was tensioned about the same as my previous generic stepper and the size was the same.
When I fired it up - the stepper was producing strange grinding-like noise as if something was mechanically wrong... the position, the belts and everything else was exactly the same as my previous stepper which worked flawlessly. I checked everything twice and it was still grinding like hell... At that point I gave up and returned the stepper to my friend - and he (generously) gave me another one - also brand new, exactly the same as this one, as I thought that maybe the first one was bad.
Flash forward a couple of months - I had to replace my X stepper a few days ago, since it failed (miraculously - the shaft got broken), so I thought to give the new Super Whopper one more try. And the noises I experienced with the first one were still there! Much less than on the Y axis, but still disturbing (like heavy vibrations). It works but it's disturbing and it is heating up very much even set to 1.6amps.
Just to clear things up - a generic Chinese stepper I was using at exactly the same position and setting with exactly the same (normal) belt tension was working flawlessly for a long time. everything is aligned properly, no obvious mechanical problem.
Does anyone maybe have any ideas what might be the culprit of it?