Router Climb-Cutting?

This week’s question comes from Ryan who asks:

I realize this question is probably a complete beginner’s question, but I saw mention to the concept of a ?Router Climb-cut”. Please can you explain what is meant by this? Thank you for helping.

And this was my response:

Hey Ryan. Climb-cutting can be a pretty risky procedure and its something you want to exercise extreme caution when doing. I always try to figure out if there is some other solution before resorting to a climb cut. But to understand climb-cutting, we first need to understand the proper way to run the router. In general, we always want to run the router AGAINST the direction of the bit. If you travel WITH the direction of the bit, the router can easily go out of your control. The best example I can think of is a picture frame. The proper direction when routing the outside of the frame is counter clockwise. For the inside of the frame, you should go clockwise. The reason for the change is because the work is being approached from the opposite side of the bit and in order to go against the bit direction, we need to change our feed direction. So if you remember the picture frame example, you should always be able to look at a workpiece and quickly decide the proper routing direction.

Now let’s look at climb-cutting. When you don’t follow the above rules, you are climb-cutting. Its a situation where you are going WITH the direction of the bit, and as a result, it requires careful attention and slight passes. Its really the same concept behind a planer or drum sander. The work is fed into the machine and the blades are cutting against the feed direction. If you reverse the feed direction, you could easily have a wooden missile on your hands. And the same thing goes for climb-cutting. So if its so dangerous, why do we do it? Well, there are some instances where the grain direction of the wood is not cooperating, and a climb cut simply results in a smoother cut with no tearout. In reality, those instances are few and far between for me. But if you have to do it, be sure you are removing the smallest amount of material possible with each pass and your workpiece is securely clamped down, otherwise you’ll have a serious problem on your hands.

Here is a good article by Tom Hintz over at NewWoodworker.com that should give you a few more tips and warnings: Climb Cutting

Good luck Ryan and be safe.