Good day
I would like to share with you the way that I cut frame members to 45° for frame.
Instead of messing with angles, I used big drafting triangle.
To overcome any small deviations from 45° or 90° of the blade, I'm using the Left and Right cutting method.
I cut all the members to "Final dimensions" (see Note) and the stop is positioned at the front to eliminates the need for long fences or pencil lines.
Note: because the stop is located at the front, every cut will decrease the frame member length by ½ kerf width, and because we are cutting every member from both sides, it will be shorten by one kerf width.
If you are using a 1/8" kerf blade, add 1/8" to the "Final dimension" of each member to get your planned dimension after cutting.
At the end, I added 2 pics of the new version with the plywood triangle and hold down clamps.
On the last pic, you can see how I made the hold down clamp:
Take a clamp, remove the fixed jaw, weld it to an iron angle, drill 2 holes and screw it on whatever you want.
Happy New Year
niki