Submitted by Matt on Wed, 05/26/2010 - 21:27
Posted in
HI,
I'm not sure if this belongs here, but since it hast to do with a p/t head, I thought this might be the right place to ask this.
I have a perfectly working P/T & Dolly system based on OM 0.82, with SMC 11 drives by Nanotec. With my own nodal head, the Nanotec steppers I use work perfectly fine.
I started to retrofit an Arrihead 2 with some old Nanotec steppers I got from ebay and discovered a strange thing. The pan axis works fine but even if I disable the tilt axis, it still moves a tiny littly bit every once in a while, even though I have set the steps to 0, the ramp to 1 and the maxsteps to 0. This does not happen with the newer steppers on my own custom head.
I switched the motors on the Arrihead, then this phenomenon is the other way round (tilt works fine, pan doesn't)
When I move either axis (with the move command), I can't really see anything unusual. It's only during a program that the tilt axis moves when it's not supposed to...
I was suspecting some sort of noise that causes the steppers to move, but why is it only with the Arrihead motors, not with the other ones ?
If I can't find out what the problem is here, I will probably just buy two more of the steppers that do work, but I'm curious what's going on here....
Anyone have any ideas ?
Matt
Matt, it does sound like you
Matt, it does sound like you have a bad stepper, or a bad driver for that stepper. I can get my new motors to make "unexpected moves" by pushing their current much higher than they're designed to safely use. It could also mean you have a bad connection somewhere along the line, and an input occasionally floats. (Once a bad wiring job caused my motors to move miraculously on their own, and especially when my hand got too near the bad connection =)
It can be real hit-or-miss with used steppers, you never know what abuse they were put through by their previous owners, or why they are selling them!
!c
Chris, the strange thing is
Chris,
the strange thing is that both motors work well on one drive (which is new and exactly the same as the others), but not on another. The settings of all drives are the same. Finally, the new motors I have work like a charm on my nodal head (with any drive).
It will work for now. Once I get the new motors for the Arrihead, I expect this issue to go away... but now you know why I'm after realtime moco. I tried to move a Red One with my motors attached to the Arrihead the other day and they only start to loose steps if I put the head in a high gear with a heavy lens on the Red. Seems like a perfect portable moco solution for me... at least for some things...
Matt