Another approach to cutting foamboard at an angle

[L Edge]

When making hinges for elevators ailerons, etc, it is hard to get the 45 degrees straight down the length of the control surface.

Solution: buy a roll of blue painter's tape.

Next, take the length of control surface and peel and lay down the side of blue tape right along the edge of one surface.

Now, turn it over and take a new lengthy of painter's tape and move back the thickness of the board to give it 45 degrees angle.

Use your eyeball to sight evenness.

Now either using a real sharp blade or fine sandpaper, cut out the segment or lightly sand until it reaches the painter's tape. The tape is designed to prevent gouging past and leaving a gap at the hinge line. With a little practice you will be an expert.

If your line is straight, you will see the unevenness of the Adam's board.

 

[Piotrsko]

Hmm beats my method of using the table saw with the blade set to 45. Also works better for embedded surfaces where you don't want the whole edge done. Much easier on short cuts, also. Doesn't have that "More Power grunt grunt" effect though that the 5 horse table saw has

 

[Bricks]

I use a small block of wood cut at 45 degrees then hot melt razor blade to the edge set to the depth of either completely cutting off the piece or leaving paper for hinge.