Quote:
Originally Posted by 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.  |
Use a through hole and a flanged bearing.
You have a couple other options--all of them involving second operations on a mill. You can use an endmill and interpolate a pocket for the bearing to sit in. If you wanted to use a manual mill, you could use a boring head and bore the diameter down to the flat.
It'd be a heck of a lot easier to use a flanged bearing and a through hole.
as for reams, check
McMaster,
Enco,
KBC Tools, etc. Pretty much any industrial supply/tooling company will have perfectly suitable reams.
You don't want 0.005 under either. More like 0.0005. a 0.005 interference fit is WAY too tight. you want a max of about 0.002 interference. You might be ok going 5 thou under in aluminum, but you could actually deform the bearing in a harder material.