mklotz
Well-Known Member
Here's something you can make in your shop to confound all those people who think anti-gravity and perpetual motion are possible if we just can get the engineering right.
[ame]http://www.youtube.com/watch?v=BG8NgF8zMvA[/ame]
It's called a double cone ascender and is a popular lab demonstration in physics courses since it cries out for a nice Lagrangian analysis.
As you can see from the video, making one is dead simple. Turn the double cone on the lathe, making an effort to get the axes of the two cones coincident. My 3jaw is pretty good so I used it to turn the cones. If yours is suspect, a collet chuck may be something to consider.
The rails are just rectangular sticks of metal. They're not critical. Use anything to hand, e.g., angle iron. The only real requirement is that they are high enough so the cone center is above the table when the cone is at the end where the rails are connected.
There's a design equation that connects the various angles involved.
tan(I) < tan(C/2)*tan(D/2)
where:
I = inclination angle of ramp
C = total included angle of cone tip
D = angle between the two rails
I used C = 45 deg. With 9 in long rails, a 1/2 in riser provides just about the maximum angle for I. (I didn't bother to measure D but, by eyeball, it's about 15 deg.)
[ame]http://www.youtube.com/watch?v=BG8NgF8zMvA[/ame]
It's called a double cone ascender and is a popular lab demonstration in physics courses since it cries out for a nice Lagrangian analysis.
As you can see from the video, making one is dead simple. Turn the double cone on the lathe, making an effort to get the axes of the two cones coincident. My 3jaw is pretty good so I used it to turn the cones. If yours is suspect, a collet chuck may be something to consider.
The rails are just rectangular sticks of metal. They're not critical. Use anything to hand, e.g., angle iron. The only real requirement is that they are high enough so the cone center is above the table when the cone is at the end where the rails are connected.
There's a design equation that connects the various angles involved.
tan(I) < tan(C/2)*tan(D/2)
where:
I = inclination angle of ramp
C = total included angle of cone tip
D = angle between the two rails
I used C = 45 deg. With 9 in long rails, a 1/2 in riser provides just about the maximum angle for I. (I didn't bother to measure D but, by eyeball, it's about 15 deg.)
