I thought I should share this..
I needed to balance the spindle of my CNC retro fit lathe..
It had particularly bad vibration at 580 rpm
I stuck an accelerometer (same as in a mobile phone) to the side of the head casting
The signal from the accelerometer was fed into one trace on a dual beam scope..
The signal from the spindle synch pulse was fed into the other trace and used as the trigger..
By judging how far along the pulse the peaks and troughs were, I was able to add and remove weight to the spindle to balance the shaft..
By the time I finished, the accelerometer was showing less than 1/100 of the movement when I started.. and it was getting hard to see what was gpoing on as the apindle vibration was getting swamped by vibration from the 3ph motor and interference from the VFD
but all in all very succesful...
video below
sorry about the quality of my commentary, I was getting tired by this time and I wanted to get the machine back together
[ame=http://www.youtube.com/watch?v=hLsVMxmxQys]Balancing Lathe Spindle with Accelerometer and 'Scope - YouTube[/ame]