|When I think about touching up my
router bits, I like to use an analogy that makes the bits a part of my shop
"wardrobe." Just like a sport coat or a sweater, an expensive bit may
need to be sent to the cleaners occasionally. But there are a couple of things
you can do at home to keep bits clean and sharp.
CLEANING. The first thing I do to a dull router bit is to clean it. I
talked about cleaning bits back in tip No. 38, so I won't go over that again
here. But basically the process involves using an old toothbrush to scrub the
bit with denatured alcohol. (Just don't soak the bearing.)
HONING. The next thing I like to do is touch up the cutting edges. For
this I use a set of diamond honing files. (You've seen these files. They're
colorful pieces of plastic about 1" x 6" with various grits of
abrasive material adhered to one or both sides.) "Touching up" the
edges of a router bit is not like sharpening. It's more like brushing your
sport coat with a lint remover.
Note: Don't try to touch up or sharpen the beveled edges of a router bit. Not
only will this change the cutting profile, it can also affect the balance of
the bit, which can be dangerous. I only touch up the flat surface (the front)
of the cutters with honing files.
Usually it takes just a couple of strops over a medium grit diamond file,
followed by a couple passes over a fine-grit diamond file. To do this, I clamp
the file along the edge of my bench. This way the flat part of the bit can be
in contact with the file while the rest of the bit extends off the edge of the
bench, out of the way.
Then I use my thumb to keep the flat surface of the carbide cutter perfectly
flat on the honing file. After a couple passes on one of the cutters, I do the
same for the other cutters on the same bit. To keep the bit
"balanced," (both cutters taking an equal bite when routing), try to
maintain the same amount of pressure on each cutter when filing. And make the
same number of strokes across the file.
Go to Tip #48