Expert Answers: Climb-Cutting: A Safe, Effective Way to Tame Tearout?Comments (0)
This article is from Issue 103 of Woodcraft Magazine.
Q: I’ve read that climb-cutting (feeding a router opposite the normal direction) can reduce tearout. But I’ve also heard that it’s dangerous. I’m relatively new to routing, and would appreciate any clarification on the matter.
A: Climb-cutting definitely reduces tearout, but it also involves an element of risk. First, the benefit: When feeding the router “backwards” like this, the bit cuts inward cleanly because the wood fibers are backed up by the workpiece itself. When fed in the normal direction, an outwardly rotating cutter that encounters contrary grain will often tear out the unsupported fibers. This is particularly a problem with tearout-prone hardwoods such as oak, ash, and just about any figured wood, as well as splintery softwoods like fir, cypress, and cedar.
Tearout can happen during any number of routing operations, including simply rounding over an edge. But it’s a notable concern when cutting panel rabbets in frames, where the shoulders can tear out. Although tearout on the outer shoulder is often hidden on the back of a frame, damage to the inner shoulder is very apparent on the finished piece. Because of this, I almost always initially climb-cut these rabbets, as shown in the drawings. I also regularly climb-cut when profiling any tearout-prone woods.
So why not climb-cut everything? Well, here’s where the risk comes in. Climb-cutting causes the cutter to aggressively self-feed, pulling the tool along with it. Countering this requires a firm grip on the router to keep it from lurching out of your hands. Because of this, always take a series of light cuts to do the job. Also, always finish up with a pass in the normal direction to ensure a cut of consistent width.
I climb-cut as needed using a hand-held router and have never ventured into danger. That said, I do not advise climb-cutting on a router table under any circumstances. It’s too easy for the bit to suddenly grab and hurl a workpiece, damaging it and exposing your hands to the cutter in the process. As with any woodworking operation, climb-cutting demands safe, sensible working practices. If something doesn’t feel right, don’t do it.
Senior Editor, Woodcraft Magazine
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