Posted by Jim Wilkins on February 14, 2010, 7:06 pm
Any toothed belt or chain will require the pulley to be an integral
multiple of the pitch in circumference, and it will have to stay that
size as the humidity changes. A bicycle chain will make trimming to
size easier because you can see the start and end pins or holes and
file the rim until they line up. That's harder with a toothed belt,
plus the grooves in the rim will be very difficult to cut accurately
in a 4' wooden disk though you may not need them on the large pulley.
You could pound in a few aluminum pop rivets, stem in and rivet out,
to act as teeth for the chain.
Here's another possibility:
I have the Jason one from Harbor Freight.
The link tabs extend down into the pulley so you may have to deepen
the vee groove, assuming you have a lathe.
Posted by Jim Wilkins on February 14, 2010, 3:59 pm
Riding mowers use long vee belts.
Before electricity, rope was used for industrial power transmission.
The small rock-tumbling (bird scaring) garden windmills I built as a
kid had many turns of cotton twine between the pulleys, joined with a
square knot. Polyester also doesn't stretch much when damp.
Bicycle chains can easily be joined into long lengths. The larger
pulley shouldn't need teeth if you use a spring tensioner, or you
could drive in a few nails and cut the heads off.
Posted by vaughn on February 14, 2010, 4:22 pm
I assume that we are not talking about much HP here, so either a flat
"serpentine" belt or perhaps even bicycle chain come quickly to mind.
Posted by harry on February 15, 2010, 7:53 pm
Once you pass the five or six to one ratio, belts and chains don't
work at all well. At least trying to do it in one step. You'd be
better looking at some sort of gearbox. Salvaged from something with
an ICE but used the other way round.
Or gearbox and belts, depends what you can find,
Posted by vaughn on February 15, 2010, 8:46 pm
I am sitting here thinking of my 21-speed bike, which is pretty damn efficient
as machines go, and I am trying to make sense of this. How could a multi-step
chain drive be more efficient?
I might also add that my bike is not terribly high priced, yet the chain drive
looks and works like new after 2700 miles.