barkster wrote:I assumed you could take a reading with the motor off on the accelerometer and then if you put a mark on the spinner and take readings at that exact time/spot you could calculate the vector of the imbalance??
The imbalance should result in a oscillating motion when sensed in any 1 axis orthogonal to the spin axis. An X/Y accelerometer, in theory, mounted to the housing should give you this in both sensing axes. Not sure how that helps (vs 1 axis) but there it is. The problems still remain :
1) You need to correlate the sensed accel to the position of the rotor. The balancer in one of you links used a strobe and a mark to do this. What would you do ?
2) The accelerations need to be large enough to be sensed accurately and the fan housing must be held to some fixture. That's some mechanical design and too stiff a connection btw the two will diminish the accelerations ... perhaps too much to be sensed by what's affordable for accelerometers. You'll need to decide how small a residual imbalance is good enough and what acceleration that will produce given your mechanical design and whether accelerometers can sense that level accurately enough.
3) The accelerometer must sample quickly enough to be able to resolve a sufficiently small rotational angle. Depending on what RPM you balance at, that could be a problem.
No doubt there are other challenges to be met but these will do for a start.