![]() As long as the lever he uses is positioned so that cylindrical cam goes over-center with respect to the point of contact and the lever is restrained from turning more than desired then it will be locked. I understand what you are saying about involutes but I don't think Bill needs to worry about grinding some fancy profile to a simple saw fence locking cam. I don't think it is going to take a whole lot of distance from true center, my 1/8" example above might be about as far as you want to go, just from a gut-feel perspective. IOW, given a long enough lever/handle, I think you can probably deform the tube section that is being clampedĪs simple as this is to make, I'd simply experiment with a couple designs until you like how it works. ![]() A shorter distance on the center hole gives a cylinder without much travel between "clamp" and "release" positions, but a lot more "mechanical advantage" to provide clampload. The basic tradeoff is that a large distance on the center hole (the 1/8") will give a lot of displacement of the round cylinder, and probably not a lot of leverage. Also, once the clamping stackup of tolerances "goes solid" and all free-motion is removed, you probably won't need much more to "lock" the cam. In reality there are a couple limitations.you probably can't achieve a full 180 degrees of lever/handle travel. This means you now have the potential of a 3/8" radius and a 5/8" radius, if the cam can be turned 180 degrees. For example, on a 1" round part, drill the hole 1/8" away from true center of the cross-section. The "cam" characteristics in this case are setup by 1 simple characteristic, how far the pivot hole is drilled away from dead center of the cross-section.Īnd so.you can use this to your advantage. I looked at the cam once and it is nearly as you described it, plus a tapped radial hole for the locking lever/handle. ![]() I'm familiar with the Biesemeyer design and the Powermatic knockoff on that same idea.
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