Chamfer Bits
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Wood Magazine

Chamfer Bits

We all know that chamfer bits work great for easing exposed edges. But did you know that with them you can cut dead-on miters with little setup involved? Here's how.

Chamfer Bits

Chamfer Bits

A great way to make on the money miters. We all know that chamfer bits work great for easing exposed edges. But did you know that with them you can cut dead-on miters with little setup involved? Here's how.

As you can see in the chart below, chamfer bits come in five cutter angles for making boxes with various numbers of sides. Note that they 45 bit we show is considerably larger than the other chamfer bits. That's because we prefer to use bits capable of making a full-edge cut in 3/4"-thick stock. For such material you need to move up to the largest 45 bits generally available -- those with a cutting diameter of 2-1/2" or more.

Note also in the chart that there are two kinds of miter cuts you can make with chamfer bits: end-grain miters (for shallow boxes or frames), and edge-grain miters (for deeper boxes). In the steps that follow we'll make both types of miter cuts with a table-mounted router.


5 CHAMFER BITS AND THE MITERS THEY CUT
 ROUTER BIT (NOT ACTUAL SIZE)
 CUTTER ANGLE
11.25° 15° 22.5° 30° 45°
 NUMBER OF SIDES IN BOX
16 12 8 6 4
 END-TO-END JOINED WORKPIECES
 EDGE-TO-EDGE JOINED WORKPIECES


 

End-to-End Mitering

End-to-End Mitering

How to miter end-to-end joined workpieces

First, install the chamfer bit and adjust its height so the bottoms of its cutting edges are just below table level. Then, set your router table's miter gauge precisely 90 to its miter slot. Add a wood auxiliary face to the miter gauge that extends up to, but just a hair shy of, the chamfer bit's pilot bearing.

Note: Perform each of the following steps on all of your workpieces before moving onto the next step.


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1. Rip your stock to exact width and crosscut your workpieces about 1/8" too long. Miter one end as shown at left. For best control make multiple shallow cuts until the bit miters the entire end.


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2. Cut a full miter on the opposite end, leaving each workpiece about 1/16" too long. Now, miter one workpiece to its final length. Then, use this workpiece to set a stopblock on the miter-gauge auxiliary fence. Cut all of the pieces as shown at left.


 

Edge-to-Edge Mitering

Edge-to-Edge Mitering

Now, let's cut miters for edge-to-edge project pieces

1. Rip and crosscut all of your workpieces to their finished width and length. Adjust the chamfer bit for a full-height cut and position your router table's fence for a shallow cut. Make this cut on both edges of all of the workpieces. Move the fence back for a slightly deeper cut and repeat, doing this until your miter cuts on both edges come to within about 1/8" of the top of each workpiece.


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2. Adjust the fence so the chamfer bit cuts the full miter without reducing the workpiece's width. (For precise results, make test cuts in scrap stock.) Make your final miter cuts on both edges as shown at left.


 

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