Geometry sucks!

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Eddie_T

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Nice workmanship!

When using woodworking tricks it's always good to understand why the trick works. The ones shown for bisecting the angle are actually intersecting parallel lines (equidistant from the legs of the angle) represented by the straight and parallel edges of the boards.

0831211105.jpg
 

68bucks

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Here's how I would calculate that angle. Measure from the corner of the house to the corner of the railing. Measure the other legs of the triangles and then apply trig functions to calculate the angles. I think I've seen some online calculators too.
Of course in real life I'd probably make a pattern or something similar.
 

Eddie_T

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Here's how I would calculate that angle. Measure from the corner of the house to the corner of the railing. Measure the other legs of the triangles and then apply trig functions to calculate the angles. I think I've seen some online calculators too.
Of course in real life I'd probably make a pattern or something similar.
A triangle with a 92° angle doesn't readily lend itself to the trig functions.
 

zannej

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Thanks for the videos, Eddie. Those were helpful.
Now if I can find a super easy way to figure out the angle of a slope for pipe drop/rise.
 

Eddie_T

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@Hamberg If your willing to tackle faux stone painting or veneering the foundation of that porch could be transformed. I have a friend that painted faux brick on a Florida concrete block stucco house. He was experienced in graphic arts though.
 

68bucks

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This might help.
 

Eddie_T

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I thought of a method using a 45° triangle and a straight edge that could work with some precise measurement and the use of trigonometric functions. However the direct no measurement bisection would probably be more accurate.
 

Hamberg

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This might help.
YUP, clear as mud!!
 

zannej

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Thanks! Dylan really is cool. One of these days I will subscribe to something. I actually saw another pretty cool trick someone used. He wanted his pipe to slope 1" over 4ft so he added a 1 inch block to the end of his level to raise it up so it would show as level when the pipe dropped 1". I've also seen they have torpedo levels with an adjustable part you can spin so that it will show as level when you have it at a specific slope. So if you find that 1/4" per foot slope and rotate the part you can use that one to tell when something is sloped properly.
 

Eddie_T

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I didn't think to try to work a sine bar into this discussion, and don't think I will.
 

bud16415

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I didn't think to try to work a sine bar into this discussion, and don't think I will.
Being trained as a tool and die maker and spending 43 years around the industry I thought I had seen every kind of sine bar ever made. But I your wooden one is something new to me. Very cleaver.
 

Eddie_T

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Being trained as a tool and die maker and spending 43 years around the industry I thought I had seen every kind of sine bar ever made. But I your wooden one is something new to me. Very cleaver.
That one is not mine. I chose the pic because it demonstrated its use. Mine is effective but not as pretty.

 

bud16415

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That one is not mine. I chose the pic because it demonstrated its use. Mine is effective but not as pretty.

I should make a wood one.

I made a hardened steel 5” sine bar when I was an apprentice way back. It calibrated within 20 millionths inch. Was good enough for the work I did.
 

Eddie_T

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I made mine 10" for convenience. I could have achieved greater accuracy by just making it and then calibrating it with a precise measurement but I opted for convenience of a x10 multiplier. I could still measure it precisely but it's OK for the pencil lines I work with.
 

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