Maintaining Router Bits
Let a pro do the resharpening, but between trips keep then tuned up with a few file strokes.
TLC for Router Bits
Let a pro do the resharpening, but between trips keep them tuned up with a few file strokes.
Router bits, even those tipped with carbide, dull faster than you might expect. It happens quickly in solid wood, and even more quickly when you work with plywood and other resin-filled sheet goods.
When a dull bit needs regrinding, it's time for a trip to a good sharpening service, which can set you back as much as $10. Only a qualified professional has the machinery and know-how that are necessary to maintain a bit's precise geometry.
However, you can prolong the time between regrindings by lightly honing the bit's flat side with a file every so often. Note that we said lightly, and only on flat surfaces. Don't mess with the bit's hook angles. Even the pros don't do that.
All you need to hone high-speed steel and carbide bits is a pair of diamond honing files. We've found them priced at $6 to $7 apiece in catalogs and at woodworking supply stores.
Start with a fine (600-grit) file and finish off with a super-fine (1,200-grit) version. Work carefully and don't overdo it. Here's how to keep your router bits on the cutting edge.
1. If the bit has a pilot bearing, start by removing it, shown at left. If the pilot isn't removable, make sure to keep the files away from it. A slight flat spot ruins a pilot.
2. Next, remove pitch and tar, which can build up in a hurry if you frequently rout softwoods. Apply lacquer thinner or oven cleaner and scrub the bit with an old toothbrush, as shown at right.
3. Begin honing with the fine file, as shown at left. Count the sharpening strokes or alternate the cutting edges every few strokes to assure that they're honed equally. It's better to do too little honing than too much. You might be surprised by how quickly a diamond file cuts even carbide.
4. Finish off with the super-fine file. Again, apply an equal number of strokes to each of the bit's flat faces and use only moderate pressure.
Lubricate the pilot bearing with light oil, as shown at right, and replace it. Also wipe the bit with oil to guard against rust that can pit polished surfaces.