trigonometry question - neck angle top relief

[peter havriluk]

I looked all through my TI-83 manual, to no avail. I'm looking for guidance on right-angle trig calculations so's I can figure out the depth of cut on a guitar rim at the neck joint so I can predict how far to cut the slope on the rim so that the angle of the top to the neck block complements the 1.5 degrees I cut into the neck blank. I can measure the length of the leg with my ruler, but doing the math to calculate how far apart the legs of the calculation are is a mystery to me.

Anybody able to help with user-level trigonometry? Or point me to something in English that can help?

Thanks!

[John Parchem]

you need to know two things, you already have one the angle 1.5 degrees. The other is how far into the body the angle is cut. From the heel to somewhere around the sound hole (the length you can measure before you slope the top)

So then you need the tangent (1.5 degrees) * that length.

For example if the length to the sound hole was 3" your calculation would be Tangent (1.5°) * 3 which is about .079 or 2 mm. You can use a scientific calculator but make sure it is set for degrees not radians.

[peter havriluk]

Thanks, John. Off to try this out.

[peter havriluk]

Glory be! Tangent of 1.5 degrees at 4.5 is .118, in this case, inches. Once I puzzled out that I had to go and pick an angle in degrees off a list of possibilities, it seems to have worked out. Twice!

Much obliged.