dc motor card for gauges

I am working on using a dc motor card to drive my air coil, steam gauge type, gauges. I put a resistor in series to drop the voltage and manually ran the commanded voltage up and down. It drove the gauge just fine, smooth and very controllable. Has anyone else done this? I guess a better question is how has anyone else done this. I could use a servo but hate to take apart a working gauge. Any thoughts or experience on this would be appreciated! :)

Perhaps a better question is what methods are others using to drive gauges using the OC cards?

Easiest way is to use a servo hooked up to an OC USBServo card. See this link for making the gauge

http://www.737ng.co.uk/Gauges.pdf

thanks for the link, that's what I was thinking too. A servo geared in order to get a larger range.