NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: "Lost Motion" Question
From: hellos
Date: 2006 Jul 17, 14:09 -0500
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From: hellos
Date: 2006 Jul 17, 14:09 -0500
Greg-
"But wouldn't any backlash
...be immediately apparent"
No. Backlash is considered to be any slippage in
the gearing mechanism. Consider this little ASCII art, if it comes over
properly:
----U----U----U----U
=A===A====A===A====
Those are uppercase "U" and "A" meant only to
illustrate a poorly fitting set and unevely made of gear teeth, i.e. the
worn smoothed teeth against the newer sharper teeth, with "wear space"
exagerated between them all. What happens if you shit the rack "A" from left to
right? Well, it engages properly in either direction. But shift it to the left,
and it hits the "U" teeth and engages/aligns in a different position from when
you shift it to the right. And as the unevenly positioned teeth wear, that will
shift a bit more too.
With or without spring loading, or grease taking
up slop, etc., that kind of "gear slop" is generally considered to be a part of
the "backlash" problem, even if it isn't truly backlash (a force pushing back).
So always working in the same direction (i.e. always go past and always come
back) simply ensures the two racks (gears, screw threads, whatever) are meeting
on the same side, which gives a more uniform and precise
result.
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To , send email to NavList-@fer3.com
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