mitre cuts

We recently had a loft conversion which meant we had to nick a bit off the box room for the stairs. They’ve rebuilt the stud walls which means that it’s now a couple off feet further into the room.They left the coving insitu and just cut it off at 90 degrees and butt the new wall up to it. This...

I'm having a nightmare trying to cut internal mitres on Screwfix Sculptured Coving 117mm x 2m using a Titan TTB710MSW 210mm Single-Bevel Compound Mitre Saw. I found a Youtube video showing how to cut a piece of wood with a 45 degree mitre and at a height so that the coving is at the correct...