|Quick Fix for Tighter Miters
It's not uncommon for the miter joints on baseboards or casing to open up, particularly
on outside corners, see the drawing.
The joint may have fit perfectly after it's installed, but quite often shrinkage
or settling seems to cause unsightly gaps.
I've found that an easy way to "tighten" these gaps is to burnish or round over
the edge with the round shaft of a screwdriver. I start by holding the shaft at
a 45° angle to the corner on one side of the joint, see the drawing above.
Try to use moderate pressure to "fold" the wood fibers along the corner point
into the gap.
Then I repeat the process on the other side of the joint. The resulting corner
isn't as crisp, but there's no more gap, so the appearance is much improved.