This is how I make angular cuts on the Preac, other than 90 degrees. The Preac came with a simple crosscut fitting (first photo) which slides in the channel machined into the top of the table. The angle is set by loosening the cap screw, setting your angle then tightening the cap screw to lock it in place. While this works, it's difficult to set angles precisely. You can use a small precision square, such as those made by Starrett to set 90 or 45 degree angles. Anything else is trickier unless you have a protractor head for a precision combination square, again such as the one made by Starrett. To solve this issue, I use precision angle blocks in combination with the sled to make precise angular cuts. Precision angle blocks usually come in sets. The set I have has 12 blocks in the following degree increments: 1/4, 1/2, 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30. Given the combination of blocks it's possible to create almost any angle. I purchased it many years ago from MSC Industrial Supply
https://www.mscdirect.com/browse/Measuring-Inspecting/Calibration-Layout-Machine-Setup-Tools/Layout-Setup-Tools/Angle-Blocks-Sets?navid=12107957.
The second photo shows the basic setup I use, in this case making a hexagonal frame. The selected angle block is set on the sled, tight up against the rail of the sled (which importantly is exactly 90 degrees to the saw blade.). I hold the block in place with a short piece of double-sided tape. Note that the end of the block does not extend into the path of the blade. I cut the stock pieces a little longer than desired and then cut one end of each piece at the desired angle while leaving the pieces a little longer than the desired finished dimension. It's helpful to use a scrap piece of wood between your stock and the angle block so that the saw does not rip out the point of the cut on its way through. This scrap piece must have smooth parallel surfaces though, otherwise your cutting angle will be incorrect. Once all pieces have had one end cut, I then set the desired final length of the cut by adding a stop to the angle block, in this case the 1/4 degree angle block held in place with another piece of double-sided tape. Then it was a simple matter to cut the the pieces to their final length by placing each against the piece of scrap stock and up against the stop.
The third photo shows all six pieces held crudely in place with little pieces of scotch tape on the underside (not an accepted assembly method

). When properly assembled, all pieces meet precisely without any gaps between the ends. Next exercise is to recreate the hexagon with proper joinery so it can be glued up.