Backlash

[vivek16]

How much backlash is recommended for gears? I am using AM gears (20 dp, 14.5 pa) and we have the option of cutting the side plates on either an old mill or a waterjet. The mill is by no means state of the art and I would guess that the tolerance is .005". The waterjet tolerance as listed on their website says .005" but our mentor assures me that they can get at least .003" if not much better.

How much backlash would you recommend between two gears? I was thinking .002" but am not really sure if that will be enough.

Also, what are some good places to get hole reamers for .005" under 7/8" and 9/8"? I am planning on having the waterjet cut a smaller hole than needed for the bearing and then pocketing that hole with a reamer so I can press fit an unflanged bearing in there.

thanks, Vivek

EDIT: err... It seems that reamers are meant to go all the way through the hole. What is the best way to make a hole like that? I am planning on using .25" aluminum and leaving a lip of .13-.15" for the bearing to sit against. Gimme a break, I'm still a n00b.