Sometime back, I attended your router class. Can you recommend a way to prevent router burn marks? I continue to encounter this problem----most frequently on end grain and inside corners, especially with ogee bits---when using a hand held PC router. The problem rarely occurs when I use the same bit on the router table.
The burn marks are nearly impossible to sand out cleanly, particularly in corners. Any suggestions you care to offer will be appreciated.
-Bill J.
Andalusia, AL
Solution to Router Bit Leaving Burn Marks
Our Expert
The heat that causes burning can have several causes. Here are some solutions:
1.Increase the feed rate. ---Probably the most common cause of burning is too slow of a feed rate. Even a slight pause as you reach an inside corner or reposition your hands on the stock can often cause burning.
2. Reduce the router bit RPM. ---Most routers today have several speeds which allows you to adjust the RPM to suit the router bit diameter. The natural tendency is to use a higher RPM. However, unless you start to see ripples or a washboard surface on the stock a slightly lower RPM will often eliminate burning.
3. Take two or three passes rather than one heavy pass. ---To avoid burning I'll often cut the profile in two or more passes. On the first pass I take a heavier cut to remove much of the stock. The final pass is a very light cut at a faster feed rate which removes any burning from the first pass.
4. Clean the router bit. ---The residue that builds up on the cutting surfaces of a bit reduce the cutting effectiveness. There are circular saw blade and router bit cleaners available today that work without harming the carbide.
5. Have the router bit sharpened. ---A router bit that is even slightly dull can burn the wood. And surprisingly, saw blades and router bits will last longer when sharpened on a regular basis. If you wait too long between sharpening more carbide will have to be ground away in order to restore the cutting edge of the router bit.
And I don't believe in honing the router bit myself. Honing a saw blade or router bit is not like honing the bevel of a chisel. Today's router bits and sawblades have a complex cutting geometry that is easily spoiled by attempting to hone the surfaces freehand. This is a job that I leave to the pros. I send all saw blades and router bits to Misenheimer Tool in Morristown, Tennessee 423-587-4300. These guys sharpen tools for the furniture industry so they have the expertise. Their prices are reasonable and once they've sharpened a tool it performs as when new.