Putting a voltmeter on the VFD will tell you nothing of value.  You need to be looking at current, which means putting an ammeter *in series* with one phase of the motor.  The Tormach load meter is nothing but an analog ammeter.  An analog ammeter contains a shunt, which is a very small, precisely known resistance.  When current passes through it, it creates a small voltage drop (typically 50mV at maximum allowed current), and the meter itself is a very sensitive voltmeter, connected across the shunt, that reads full-scale with 50mV across it.  Look at digikey, mouser, and other electroincs supply houses, and find one with a suitable full-scale reading.  But, a good analog ammeter will not be cheap.  However, a digital meter, in this application, would be completely useless.

Putting a amp meter in series, or using a clamp on type with a VFD 3 phase output to the motor is useless. The VFD voltage is not a true sine wave and the frequency varies the motor speed. This will cause the amp meter to read incorrectly. All amp digital displays on VFD's are a calculated value corrected to 60 or 50Hz. The only way is use the 0-10V analog output or modbus. 

I'm a drives field service engineer and work on VFD's up to 5000 hp. AC drives today including cheap Chinese knock off use IGBT's in the power output sections. Clamp on amp meters on the motor t-leads will not give accurate readings. Drives setup in V/Hz mode as are most low cost drive used in CNC application (not vector mode) will output without a motor connected... motor impedance (xd') has very little effect on drive filtering. I could debate drive theroy with you but I think it would be beyond most of the forum readers. I've had a number of customers state their clamp on amp meters don't agree with the drive digital display...

Quote from: Hood on July 19, 2013, 11:40:37 AM

I will certainly be doing this when/if Brian ever gets his finger out his arse

What!!! - You mean he's typing one handed?  FM - that's gotta slow things down alright

Ian