This project started with a rough plan in my head. I didn’t take the time to draw the design in CAD first, but went straight out to the shop. I’m happy with how it turned out and I am fairly confident that I will be using this in the future. See the video below.
In February of 2012 I made a couple of cam clamps that used the Bernoulli spiral for the cam design (don’t ask why). I found myself using them frequently. They were very useful for card scraping and hand planing. I thought I would come up with a system that would allow woodworkers, that don’t have dog holes in their bench, to use these clamps. I mixed the features of a bench hook and my Bernoulli Spiral clamps and came up with what I’m calling Cam Hooks. I think it has a nice ring to it
The Cam Hook has at least two advantages over a traditional bench stop. One, is that a bench stop is prone to causing your work to pivot; the cams do not have this problem. You also are not limited to the length of the stock you can clamp with the cams.
The jig works by measuring the amount of stretch in the bandsaw blade as force is applied by the bandsaw tension spring. Every 0.001″ of blade stretch is equal to 5,800 psi of tension over 5″ of blade.
When resawing, blade manufacturers recommend a blade tension of 15,000 psi. Therefore, you would need 0.0026″ of blade stretch in order to reach the recommended amount of tension.
The wider the blade, the more force will be required by your bandsaw tension spring to reach the amount of stretch required for 15,000 psi of tension. The amount of tension (15,000 psi) should be the same regardless of the width of the blade; the amount of force required to achieve it will be different.
The 5,800 psi above is derived from the following equation using Young’s modulus for steel:
29,000,000 = Young’s modulus for steel.
S = blade stretch in inches.
D = length of blade measured in inches.
If we plug in a blade stretch of 0.001″ for S and a distance of 5″ for D we get :