Last week I hung a new internal door. Had longer and shorter panels. Of course longer panels should be on the upperside and shorter panels towards the lower half when the door is hung.
I had to cut about 15-20mm (from memory) off from length. I sawed the end on the longer panel side of the door.
Problem occured: Basically I cut out the wood on the end. I had to glue it back in. Why was the amount I could cut away from the end of the door so small before I cut out the wood end? Should I have been cutting the bottom of the door?