[singron]

I think you could use the two shafts to align and attach the mounting bracket by drilling two holes the proper distance apart. Drilling holes is pretty easy compared to cutting straight lines and I think most people are more likely to have a drill. If you use a piece of wood, the additional thickness can help the shafts to keep the wood perpendicular. You might not need any additional fastener, and the lack of fastener could help it return to a neutral position after operation rather than migrate. Also, slowing down the stepper motor can reduce unnecessary forces and the likelihood of malfunction.