Thread: Octagonal box tapered lid

Not sure if this will help, I have never used it. Compound Miter Saw Calculator

I bookmarked it a long time ago figuring one day it might be useful.

The compound mitre calculator posted by Pearo is what you need. When making the triangles, cut the sides going to the apex first, with the blade tilted and the mitre gauge at an angle. Then, make a plywood or MDF template with a 'notch' in it of the apex angle. Set the template against the fence with the apex towards the fence, so that the blade will cut at at the reqired distance from the apex. Set the blade at the required angle. I use a piece of wood with a rubber furniture foot to hold the wood in the jig against the fence while cutting it.
Note - you may need to have the fence on the different side of the blade to usual, to get the correct angle on the third cut.

Thanks Pearo and AlexS.
Great info.
I had to push on with the boxes, so went with a flat lid.
I rescued one lid, failed bevel angles, by filling the bevel gaps with araldite and colour. Will be OK I think. Photos show underside of lid. A bit of work to be done still.
On the next octagonal, I'll use the formula in the link.

Love the timbers you have used, Lyle. What are they?

Nth Qld silky oak, Camphor laurel, beech.

Body of box, although hard to see, are jacaranda with red cedar inlaid stripes.
Lyle

The outcome is what it is but getting there is the fun part. trying something different is good exercises the grey matter.