Wood cutting tools. Circular saw
When you are using a circular saw to cut a hollow-core wood or solid-core wood door to length you will end up with slivers on the cut side of the door caused by the rotation of the saw blade. There are a few tricks to cut down on the amount of slivers or to eliminate them 100%. Some apply a strong tape on the door where it has to be cut or scorch the surface of the door with a utility knife where it will be cut. Of these two methods the last one is the best but unless a straight edge is used to guide the saw along the cut line there still will be some slivers. Many years ago a skilled finish carpenter from Portugal taught me the perfect way of cutting a door to length. The cut will be perfectly straight with no slivers and so smooth not even sandpaper was needed! Over the years I have told others about how to make the perfect clean cut but strangely enough I never met a person who knew about it. So, here are the nine steps to follow to get a clean cut:
1. Remove the door and place it, laying flat with the hinges down, on a set of saw horses.
2. Take a 10" (25 cm) or wider piece of paneling, underlay plywood or other thin plywood and cut it to length, (door width + 2" [50 mm]).

3. Clamp the piece of paneling to the door, flush with the bottom of the door and leaving it overhanging by 1" (25 mm) on each side.
4. Go to the door opening and measure the door height on the hinge side and on the doorknob side.
5. Mark the length of the door on each side and draw the cut line on the piece of paneling.
6. Measure the width of your circular saw support base, from the outer edge to the saw blade. If this is, lets say 6" (15 cm), go back to the door and draw a second line on the door 6" (15 cm) away and parallel to the earlier drawn cut line.
7. Clamp or nail a straight edge even with the second line. The straight edge should extend at least 6" (15 cm) past each side of the door. The extra inches on each side will make it easier to start and exit the cut.
8. Cut the door along the cut line using the straight edge as a guide. While cutting apply downward pressure on the saw to make sure that there is no gap between the door and piece of paneling.
9. Remove the piece of paneling and you are done! The slivers are on the plywood and not on the door and no sanding is required.