A clean bits cuts better and lasts longer than a bit coated with pitch. As pitch builds up behind and in front of the cutting edge, the clearance angle is effectively reduced, and chip ejection is reduced as well. The bit has to work harder and becomes dull more quickly.
How to clean router bits
There are a variety of cleaning preparations that can be used to clean bits and some of these purport to lubricate the surface of the bit as well. While these cleaner/lubricants can extend the time between sharpenings, they will not make a dull bit sharp. These products may contain chlorinated solvents, denatured ethyl alcohol and petroleum distillates, so you should avoid breathing them. As an alternative to commercial cleaning preparation, you can soak your bits in paint thinner and brush them occasionally with a bristle brush.
Pilot bearings benefit from a bit lubrication. Here is where one of the spray lubricants can do some good. They can flow around the shields into the bearing and once the vehicle evaporates a dry lubricant is left behind. Liquid graphite lubricants, which are available at hardware stores and auto-parts stores, will also lubricate bearings well.
Router bits should be stored in their original packaging or otherwise protected, not be thrown loose in a box or drawer and allowed to roll against each other. Since I like to be able to inspect all my bits when looking for a particular profile, I drill holes just slightly larger than the bits’ shank sizes in a scrap block and store my bits vertically. That way the bits are available for inspection, they don’t bang one another and I can carry them easily to wherever I am working.
Check out this video for more on cleaning, maintaining and sharpening your Router Bit from MPOWERTools
How to increase router bit life
Here is how to get more mileage and longer life from your router bits.
Never overload or abuse a bit. If the job calls for cutting away more than the equivalent of a 1/4″ square area, make multiple passes with light cuts. Consider a 3/8″ square as the upside limit for most cuts.
For lots of heavy duty routing, use 1/2″ shank bits if your router accepts them. They are stronger, stiffer, deflect less and easier to regrind.
Use bits with the shortest cutting edge and the largest cutting diameter that you have. When possible, select bits with high hook angles and larger gullets for fast chip ejection – they will run cooler and stay sharp longer.
Use sharp bits. If you are burning wood, having to apply more than the usual feed force or getting chattering while cutting, suspect a dull bit. Consider sharpening your router bits.
A router of 1 1/2 hp or more will cut at a faster feed rate and at the same time won’t heat up the bit as fast as a router with less power.
When mounting a bit, insert the shank into the collet and finger tighten the lock nut. Twist the bit several turns to let it seat itself. Then, lock the bit with 3/4″ to 7/8″ of the shank captured in the collet. Do not insert the shank all the way to the bottom of the collet.
Set router speed to spin the bit at its optimum rpm. Bits over 1″ in diameter should be slowed to cut satisfactorily and not overheat.
Use a two-cutter system. Do most of the rough cutting with one bit, then make the final cut with a new or freshly ground bit with low mileage.
Look for uneven cuts caused by extensive wear on a portion of the bit. This defect could produce poorly fitted joints. Sharpen or replace the offending bit.
Clean and lightly oil bits after use. Sand the shanks smooth with emery cloth. Clean and check the collet frequently for wear. Lubricate the ball bearings after each use.
Store bits so cutting edges and bearings do not get damaged.
Speed limits for bits!
Although routers rely on high speed for their performance, larger bits should turn at slower speeds in order to keep the tip speed at a reasonable level. For example, a 3/4″ diameter bot spinning at 22,000 rpm has a nice mundane tip speed of 49 mph. By comparison, the tip speed on a 2 1/2″ diameter bit spinning at the same rpm will hit 164 mph. Some experts suggest that a 130 to 140 mph tip speed should be the maximum for optimum performance and operator safety.