UKC

I'm trying to think of the easiest way to cut a 45 degree bevel on a tetrahedral volume so that it is flush to the wall. Obviously I could hand saw each of the three pieces but getting these to line up well must be difficult. Woodwork gurus, is there a better way?

Paint (sand mix) to use, in keeping with a bright, textured wall. What is best?

Finally, will 18mm ply be too much?

Also any tips? This will be my first volume.

In reply to Jackwd:

Circular saw or table saw. Sorry, I can't remember the geometry required to calculate the angles you'll have to set the saw to but if you mock it up to scale in something easy to work you can measure them directly. If you only have a hand saw cut a straight edge then plane the bevel.

18mm seems a bit heavy to me, I'd be inclined to go for 12 or 15mm and add internal ribs to the bigger surfaces for stiffness if required.

jk

In reply to Jackwd:

Sketch up is your friend here, it's free and easy to use.
As for the ply, I would go 18mm.

In reply to Jackwd:

The angle at the bottom of the sides doesn't need to be exactly 45 degrees - it's only the outer edge that needs to be flush so the bevel can be more than 45 degrees. You won't notice when it's screwed into place (although the cut needs to be pretty close to 45degrees to make sure that there's enough wood for the screws to go through)

In reply to Jackwd:

18mm ply is ideal. Wikipedia is quite useful for angles for polyhedra. I use Coo-Var grip paint, works well, but be sure to give it plenty of drying time! To get the bevels to the wall I use a planer on the individual pieces and finess that with a sander on the finished volume. Important is to sand the edges where pieces meet, if you leave it too sharp it's easy for a foot to peel a bit of ply off, plus it's too good a hold generally. I also use brass inserts in the screw holes, avoids screws pulling through if the volumes are moved often.

In reply to Jackwd:

Are you going to have screw-on or bolt on holds mounted on the volume too, or is it going to be a stand alone 'hold' itself? Either way, I'd be inclined to go for 18mm ply nomatter what.

In reply to Jackwd:

Thanks for all the help. We've made some volumes, two tetrahedrons and a hand crack, comprising of two elongated triangular boxs opposing each other. We've struggled with the paint mix to stick so we bit the bullet and bought some Coo-Var, expensive stuff though!

In reply to Jackwd:

Would be good to see how they look.

In reply to rockjedi12345:

I will get some photos once they're finished.