Avoid Chip-out When Pattern-Routing
I'm making a pedestal shaped like an hourglass. I traced the pattern to the oak workpiece, cut it with my jigsaw to within 1⁄8 " of the line and screwed the piece to a template. As my router nears the end of the piece, I'm routing diagonal to the grain and the corner breaks off. Should I step up from a 1⁄2 " to a 3⁄4 " pattern bit?
—Dean Davis, Moosup, Conn.
Instead of a larger pattern bit, Dean, consider trying a bit with a slanted cutting edge, such as the one above, or a spiral flush-trim bit, like the one shown below. Use an upcut spiral for table-mounted routers or a downcut spiral for handheld work. Either can be ordered from MLCS (800/533-9298 or mlcswoodworking.com). Both the slanted and spiral bits cut with a shearing action rather than the chopping action of a straight cut, leaving a smoother surface and reducing chip-out.
Next, make less work for your bit. Rough-saw your workpiece to within 1⁄16 –1⁄32 " of your pattern to stop splintering and tear-out.