CiB Trigonometry for cutting angles

2010-09-04 21:30:00 GMT-0008 until Burning Man 2010.

And you thought that high school trigonometry class would never be useful!??

 

An R function for calculating the amount to mark from the edge.

f <- function(degrees=45, y=1) {
   rad <- (90-degrees) / 360 * 2 * pi
   x <- y/tan(rad)
   x <- round(x,2)
   return(x)
}

Running this in R gives the amount to cut off for 4 angles and for 2 thicknesses.

> f(c(30,45,60),1)
[1] 0.58 1.00 1.73
> f(c(30,45,60),2)
[1] 1.15 2.00 3.46

 

Here are the measures necessary for the marking gauge based on the three angles used. I used 1" sheathing, but I also provide measures for 2" thickness.

 
angle of cut
15°
30°
45°
60°
sheathing
thickness

1"

 0.27"
0.58"
1"
1.73"

2"

 0.54"
1.15"
3"
3.46"

 

For example, to cut a 30° angle in 1" sheathing, scribe 0.58" from the edge.

 

To cut a 45° angle in 1" sheathing, scribe 1" from the edge.

 

To cut a 60° angle in 2" sheathing, scribe 3.46" from the edge.