On Sat, 05 Jan 2008 22:58:34 -0600, Paul wrote:

DoN. Nichols wrote:


I like the idea of putting a tach display into the project box
with the speed control pot --

This VFD has an output for a tach, scaled either for a 1ma meter or some
strange 8 volt square wave signal. Your idea of a tach pickup on the
spindle is better as it's actual feedback and not what the drive merely
thinks the speed is based on it's output.

From the pics, the VFD appears to be a Mitsubishi FR-A5xx. A nice
feature of these drives is that it's easy to remote the operator panel
with an RJ-45 network cable. The display can be scaled to display
machine speed, and if the drive is running in flux vector mode (which
you should definitely be doing since you want full torque at low
RPMs), the display is based on what the drive is sensing from the
motor, not simply output frequency. Of course you'd have to do the
mental math to account for the speed reduction when in backgear.

--
Ned Simmons