Thanks, Ray and others, for a bunch of good comments and ideas to work
on. My stack of questions is not, however, finished, but rather keeps
stacking up....
On 14.3.2011 20:00, ray_harlan wrote:
> For ball bearings, a "suitably large hole" would have a tolerance on the
> order of .0002", not something you get with a drill. The holes are
> drilled undersize and then bored to size. You can increase this
> tolerance a bit, if you Loctite the bearings in, instead of pressing
> them. But anything over .001" could lead to sloppy gear mesh. As Art
> points out, the most important thing is the center distance between two
> gears. Too close and they bind; too far, and they get ratty. A 32 pitch
> is pretty good for any indoor winding. Class of gears also is important,
> but you don't need super gears. Most nylon or Delrin gears are molded
> and fit in one of the lower classes. They still should be fine and are
> what A2Z uses. Phenolic gears are machined and are quiet like nylon.
I was considering aluminium gears from ServoCity for the strength, but
maybe plastics would be strong enough? Is deldrin/acetal molded or
machined? From the price I gather molded?
Does gear size affect the gear friction? Is 32 pitch coarser (to rotate)
than 48 pitch? What to go for?
> If you make a winder, it would be best to mock it up using a milling
> machine with a digital readout and fiddling with center distances until
> the mesh feels good (just outside of binding). Two plates on standoffs
> works fine.
Another idea: attach the gears to smaller plates that attach to the main
body with a couple of screws in oval holes. This way you can loosen the
screws, slide the axis until gear distance is good, then tighten the
screws and secure with loctite. If there is a sub-plate in between the
main plates (as in Arts' winders) the input and output axes can be in
line with each other, and if the gears for the first and second phase
are similar (same number of teeth, then it will suffice to move the
intermediate axis....
-Tapio-
Received on Mon Mar 14 2011 - 11:14:30 CET
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