Slot Cutter Router Bit for Spline Grooves, 1/4 in Shank

A new frame for pressed cane, whether a cabinet door, a framed panel or a chair you are building, needs a groove for the spline. This bit cuts it. It is a carbide slot cutter with a bearing on top and a 1/4 in shank, in three widths that line up with the three most common spline sizes:

• 1/8 in groove for #7 spline
• 3/16 in groove for #8 spline
• 1/4 in groove for #9 spline

The thickness of the cutter sets the width of the groove, and the bearing riding against the work sets how deep it cuts. Feed at a steady, moderate pace instead of forcing it; the cut comes out cleaner and the bit runs cooler.

Before you cut the real piece, run a test groove in scrap of the same wood, soak a short length of spline and tap it in. It should go in with firm tapping and sit flush. Adjust on the scrap, not on the frame.

This bit is for new work. An old chair groove only needs cleaning out, which a caning chisel does without changing its width.

Safety, every time:

• Use it in a router table or a handheld router with the guards in place.
• Wear eye protection; hearing protection is wise too.
• Unplug the router before you change or adjust the bit, and tighten the collet fully on the shank.
• Clamp the work or hold it firmly against a fence, keep your hands well clear of the cutter, and use push blocks on a router table.
• Let the router reach full speed before the bit touches the wood, and feed against the bit's rotation.

Decide on the spline first, then buy the bit to match it: #7 spline needs the 1/8 in bit, #8 the 3/16 in, and #9 the 1/4 in. If you are making a piece to sit alongside caned furniture you already own, measure those grooves and use the same size, so the spline lines look alike.

Check your router before you order. The bit has a 1/4 in shank, so the router needs a 1/4 in collet.