How to cut treads between housed stringers
You can use a tread wizard. But for those who do not own one. The solution is still easy to do IF you are careful. I use a couple methods.
1 lattice strips and a hot melt glue gun- works well and doesn’t taken long. This is the same technique countertop builders utilize. Hot melt the strips on the four edges and transfer the lines to the replacement tread.
2 construction paper and tape- works for retro treads and tread replacement. Tape the paper to the tread creating a template to follow with the saw. Use blue tape, attach it first to the perimeter. Cut some construction paper a little smaller than your blue tape line. Tape that piece on your first tape going around the perimeter. Carefully pull it up as one piece and transfer to your board.
3 Bevel square and tape measure and 2 ft level- this method requires a little extra care. I only use if I have a couple treads. I check that the riser is straight along the long edge, if you can shim straight, do so. If not, use a straight edge against it to run your bevel square against. Transfer that mark to your new read. Then do the same for the other side.
Bevel cut the side and back edges for a tighter fit. Do not put a bevel on the last 1 1/2 inch of the sides where the front bullnose is. I use my saw set on a bevel for this cut. See below
This the side view of the bevel cut. I use a skill saw set on a bevel. Making sure not to cut the visible part of the front bullnose. If you did everything right it will just drop into place.
Here is the side view of the tread against the stringer. We primed and painted the stringer before we dropped the tread in. The tread was also stained and coated before installation. This method leaves a crisp line.