Build a triangular garden bed

[Qvint]

Hello!

I've attempted to build a triangular raised bed and want to cut the boards so I can assemble them with the end grain against each other. It's become apparent that geometry is not my strong suit; how should I approach this?

The plan is to have the dimensions 2550x1900x1900mm and I've calculated the degrees that the angles should be, but I'm struggling with that when I try to cut. The angles end up too wide, preventing the triangle from "forming."

My thought was that you'd calculate the angle in a corner, divide it by two, and then cut both ends at that angle against each other. Am I thinking totally wrong?

 

[Pjosk75]

Hello!

Do the angles in the image match the ones you use?

 

[Qvint]

Yes, so I cut at angle A and B with 24 degrees "inward" so that the end grain would meet.

 

[Qvint]

These are untrimmed parts, but here I trimmed the red-marked parts at 24 degrees on the miter saw and it didn't turn out well as I described in the post.

 

[Pjosk75]

From the little I remember from mathematics, it would have worked to halve the angles if it were an equilateral triangle. 180/3=60/2=30
Now one side is longer and the angle needs to be divided perpendicularly to the opposite side. I'll see if I can find an image that shows this better.

 

[Matti_75]

Your angles A+B are 180-~49= 131*/2=65.5* so you should cut to get it right

 

[Qvint]

Ah okay, is that how you're supposed to calculate. Thanks!

Follow-up question then, if your miter saw can only be angled to 60 degrees. What do you do then?

 

[Pjosk75]

You can use a template that is 45 degrees, for example. And then set the saw to 20.5 degrees.

 

[Qvint]

Both of your tips worked super well, thank you so much for the help!