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QUESTION:What do you call a straight-edge that has one of its sides so perfectly
notched that the teeth of a bicycle sprocket (the 'cogwheel' thing) will
mesh perfectly into it? Naturally, the spacing of the notches on the
straight-edge is going to depend on the spacing of the teeth, and this
is going to vary quite a bit. I don't think that what I am looking for,
is found at a bicycle shop, I'm probably going to have to go to a machine
shop to get one, though I'd prefer getting one on the cheap rather than
buying something brand new, or worse - shudder - cut one out of a metal
yardstick using a Dremel.
I'm trying to build a bicycle-powered 'forklift' if that helps anybody
understand my objective here. The platform is supposed to rise up from
the jacking action of a cogwheel cranking the straight-edge up from
under.
I only want the 'forklift' to go up 3 or 4 feet or so, and no higher.
Can anybody speculate what kind of a price should I expect to pay for a
straight-edge that has one of its sides notched in the fashion described
above?
ANSWER: Unless you can handle heavy side loads and considerable torque on the
pinion, a rack and pinion is not a really great lifting mechanism for
more than just trivial weight.
Why not build a mast a bit taller than the top of the range that you
want to reach, hang a free-wheeling sprocket there, loop the chain
over it, and use the chain to pull the load up? That's the way it's
done on lots of forklifts. This has the distinct advantage of needing
no custom-machined rack.
One pair of notes:
If you want the rack to travel and the pinion to stay fixed, bear in
mind that the rack must have someplace to go, *and* somplace to start
from. If it's intended to rise 3 feet, there has to be at least three
feet of space below it for the rack to occupy before it starrts to
rise.
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