geometry genius required
I've obviously lost more brain cells than i thought, so I need help.
I'm using the router table, with a Trend box joint cutting bit. This is the one that cuts 4 slots in one go.
If you cut four slots in one piece, and four slots in another piece, when you invert one of them, its a perfect joint. If you place the two pieces at 90 degrees, you have a perfect 90 degree box joint. O.K. so far?
Now, Having seen that mryni mini jig thing the other day on here, where you cut 45 degree angles on the table saw to get an octagon box, i thought that would work on the router table.
The cutter is horizontal rather than vertical but then the wood is also out of phase, so it will work. Yes?
Heres where I cant work out what went wrong.
I set the wood against the fence at 45 degrees to the normal fence, and adjusted the cut so the back of the cut slot is in front of the guide bearing.
I now have 2 x slots cut at 45 degrees to the fence. Why, when I put the two pieces together, do i get an angle of TEN degrees less than 90?
I could understand 22.5 if I had them out of sync, but why 10 degrees?