A $25.00 magnetic base dial indicator from Ebay or Harbor Freight Tools is a much better and more accurate way to check gear backlash. I usually try to get to .010"-.015" if possible. The tooth contact pattern, checked with white lead paste or Prussian Blue is at least as important as backlash, maybe more so.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!