Thread: Help me understand compound mitres

Have a look at the comp angles app on the iOS AppStore .


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A common way to cut feet or tops is to place a block of wood on the floor (a level surface) that is at the height of the cut required and sit a pencil on it and mark around each leg then cut with a hand saw, no need to work out the angles. I don’t have any way of helping with the table saw though, sorry.

Originally Posted by qwertyu

Im confused at the angle I had to cut the legs so they sit flat on the ground and against the table top.

When I marked out the timber before cutting, they are all 45degrees. However, when I tried to cut it on a mitre saw (offcut) set with the bevel to 45 and mitre to 45 it didnt match the angles I drew on the legs. I had to actually cut it at with a 45 mitre and 35 bevel - only way I figured it out was because the saw has a laser. I ended up cutting it it on a table saw with mitre gauge set to 45 and blade set to 35.

So how come when doing a compound mitre, 35 degrees becomes 45 degrees? In the future, how would one calculate what to set the tool to or other angles? (I drew it up first in fusion 360 which showed they are all 45degrees which is how I knew which way to mark out where to cut and if it wasn't for my mitre saw's laser I think it wouldve been impossible for me to figure out bevel angle)

it all relates back to reference surfaces.
when you do the cutting, one surface of the leg acts as a reference (0 degrees) from which the other angles (45 degrees Y-axis, 35 degrees Z-axis) are measured.
when you make the drawing, you almost invariably use different reference surfaces (front face, top face) when determining angles.

sometimes it's easier to hold the piece at one of the required angles and then cut the required surface using a 90 degree blade and a mitre gauge

This might help https://fwmedia-mkt-prod2-m.adobe-ca...0924-handyshop

it was in my mail feed today.
I have no knowledge or opinion of the book (or reference source) the article is attempting to flog.