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It's worth checking what its effective length is.Borrow an accurate angle plate of angle 'A'. Put it on the bar and use gage blocks to pack the bar up until the angle plate is horizontal as measured with your DTI. Call this stack height 'h'. Now the effective length of the bar is:EL = h / sin(A)The effective length should be very close to your design value of 5".
\frac{\partial}{\partial x}\text{asin}\big(\frac{h}{x}\big) = -\frac{h}{x^2 \sqrt{1-h^2/x^2}}
Say $h=2.5$ inches, the stack of gages you are using for a target angle of $A=30$ degrees ($\pi/6$), and $x = 5.0$ inches, the target length of the sine bar (we assume the rolls are dead on 1/2", though you can revise the calculations below).The partial derivative of $A$ w.r.t. $x$ gives an indication of how off your actual angle would be for small mistakes in the knowledge of $x$. (good enuf calculation for what we do) Code: [Select]\frac{\partial}{\partial x}\text{asin}\big(\frac{h}{x}\big) = -\frac{h}{x^2 \sqrt{1-h^2/x^2}}So, if you are off in the length of the bar by small amounts that you should be able to measure, then the percentage (%) you are off in the angle is very small. If you are wrong 0.001" in x, the angle is off by 0.022% If you are wrong 0.005" in x, the angle is off by 0.11% If you are wrong 0.010" in x, the angle is off by 0.22%Unless you have a very expensive electronic angle gizmo, I doubt that it has an accuracy that can get close to getting 0.22% around a 30 degree angle... You should be happy with the sine bar, and enjoy it without fear!tom
[...] I did not understand one single thing in your post when I see lots of numbers together my brain runs into a corner and whimpers