Bozo
June 2, 2008, 11:13 PM
I also noticed that his site hadn't been updated for 2 years. Given what all can happen when you're moving heavy things, he could be laying out there under one of those 20,000 lb chunks of concrete. Or maybe he's waiting to update until he has all the stones in place.
I did a study of levers for a special project, and learned that gears are also levers. I needed to move a sliding gate 15" but only had room to move my lever half that distance. I studied 4-bar mechanisms (http://en.wikipedia.org/wiki/Linkage_(mechanical)) I found in a 1929 mechanical engineering handbook.
One of the mechanisms was called a stroke doubler. It had two racks (http://en.wikipedia.org/wiki/Rack_and_pinion) with one pinion between them. If the bottom rack is fixed, and you apply your stroke to the pinion, the top rack moves twice the distance as the pinion. The top rack is the output link.
So I puzzled over that, and went round and round with it, until I sorta understood how it worked. But I couldn't figure out how to size the pinion. What diameter pinion do I need to get the 15" of stroke. So I went next door and asked the CAD guy at the machine shop. He told me, from looking at my diagram, that it wouldn't work so I didn't need to figure a diameter.
I made a model of it with popsicle sticks for racks and a coin for the pinion. The engineer couldn't believe what he was seeing when I demonstrated it. Turns out it doesn't matter what size of pinion you use, it will always double whatever stroke you apply to the pinion.
I'd give a hundred bucks for a copy of that book I had borrowed. Published 1929 by the University of ....wish I could remember, titled "Levers".
I did a study of levers for a special project, and learned that gears are also levers. I needed to move a sliding gate 15" but only had room to move my lever half that distance. I studied 4-bar mechanisms (http://en.wikipedia.org/wiki/Linkage_(mechanical)) I found in a 1929 mechanical engineering handbook.
One of the mechanisms was called a stroke doubler. It had two racks (http://en.wikipedia.org/wiki/Rack_and_pinion) with one pinion between them. If the bottom rack is fixed, and you apply your stroke to the pinion, the top rack moves twice the distance as the pinion. The top rack is the output link.
So I puzzled over that, and went round and round with it, until I sorta understood how it worked. But I couldn't figure out how to size the pinion. What diameter pinion do I need to get the 15" of stroke. So I went next door and asked the CAD guy at the machine shop. He told me, from looking at my diagram, that it wouldn't work so I didn't need to figure a diameter.
I made a model of it with popsicle sticks for racks and a coin for the pinion. The engineer couldn't believe what he was seeing when I demonstrated it. Turns out it doesn't matter what size of pinion you use, it will always double whatever stroke you apply to the pinion.
I'd give a hundred bucks for a copy of that book I had borrowed. Published 1929 by the University of ....wish I could remember, titled "Levers".
