CMT USA Inc. has introduced two new cutter sets that should be a welcome addition for shops working with mortise and tenon joinery and related applications. The new CMT tenon cutting router bit and CMT slot cutter set both emphasize adjustability and precision setup within common sizing frameworks.

Tenon cutting bit

Featuring four wing-style carbide cutters stacked on a 1/2-inch shaft, the tenon cutting bit is designed to produce perfect-fitting tenons even in boards that vary slightly in thickness by cutting both shoulders of the tenon at the same time. Included 1/4-, 1/8- and 1/16-inch spacers allow you to vary the tenon thickness from 3/16 inch to 3/8 inch by sixteenths. Tenons can be produced up to 1-1/16-inch long in stock up to 1-3/8-inch thick.

In use, the bit was well-balanced and cut smoothly. CMT recommends keeping the router speed at no more than 12,000 rpm, and naturally a bit this size is only safe for table-mounted router applications. Adjustment is simple and straightforward with the measured shims, but CMT even includes a chart showing which combinations of shims give which tenon sizes. The whole thing is packed in an elegant wood box.

Slot cutter set

CMT's slot cutter set includes seven anti-kickback carbide cutters and four bearing arbors, plus shims. The four bearings allow cutting depths of 5/16, 3/8, 1/2 and 9/16 inches. The cutters themselves range from 1/16 to 1/4 inch in thickness and can be used in a wide variety of combinations on the arbors to produce both slots and tenons.

However, unlike the previously described tenon bit, these cutters aren't directly stackable and do require shims between cutters in all applications. But the distance between cutters can vary from 1 to 1.7mm.

Shims must also be used between the ball bearings and the cutters.

CMT describes these bits as good for biscuit joints, grooves and rabbets. Although the instructions that came with the bits don't specifically say so, again, we'd recommend these only for table-mounted operations for safety and stability. Test cuts were clean and precise. The set comes packaged in a foam-lined, blow-molded plastic case.

For more information about either the tenon cutting bit or the slot cutter set, visit

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