I would like to make an arbor with a pointed top to match my roof line. I know the roof angle is 120 degrees. What angles do I need to get my arbor top to be 120 as well? I have absolutely no idea what formula I would need but my guess is 60. Does that sound right?
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claydowling
Wed, 07/06/2011 - 08:31
That should work
Practical geometry is slightly more useful when woodworking than the more numerical variety taught in schools.
To do this via practical geometry, follow these steps:
* Draw the angle you want (never mind how many degrees).
* Bisect the angle using a compass. The angle between the sides and the bisection is the angle to use for cutting two boards to meet at the original angle.
* Copy the bisected angle (i.e. the cutting angle from the previous step) using a sliding bevel.
* Make your cut at the angle you saved with the sliding bevel.
This kind of cut can sometimes be a nuisance with fixed base saws like a mitre saw or a table saw. A hand saw would be easiest, if you first take some practice cuts on scrap to learn how to make good square cuts. Logan Cabinet Shoppe probably has the best videos about how to do it. The cheap Irwin panel saws from the big box stores are pretty good; you don't need anything real expensive unless you were going into hand tool work in a major way.