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Hi,

I would like to make a long rod move forward 4 1/2 feet along it's axis
and then return to the starting point with constant velocity and a
period of about 3 seconds. This is like the piston in a car engine but
slower and larger distances. Using piston terminology if I turn the
crankshaft then the piston will move up and down. But the piston
doesn't move at constant velocity since the crank shaft is moving in a
circle. If i built a big version of a piston I'd have to have a crank
shaft 4 1/2 feet in diameter which is pretty big. If I go with the
piston type set up it will all be plywood and bolts just so you have an
idea of what I'm working with.

Any clever solutions?

Thanks,
Peter



Peter

Is there any way you could make use of the concept where a line, like a
string, could be attached to a 9 foot long shaft?? If the string is
attached to one end and at the middle, then looped around a perpendicular
shaft so when that perpendicular shaft is twisted it pulls the 9 foot shaft
along its axis. 4 1/2 feet is used for the "thrust mechanism and the other
4 1/2 feet it your extending shaft. I suppose this isnt clear unless you
already know what I'm referring to. I have seen this "string around a
shaft" used to tune old radios where a dial is moved left to right as the
tuning knob is turned..

Jerry