Are you ready for a benchtop mortiser?
You have many options (including chain-drilling, hand cutting, and routing) for making mortises, and your need for speed may motivate you to buy a dedicated machine. Benchtop mortisers (sometimes called "hollow-chisel mortisers") cut mortises faster--and cleaner--than drilling a row of holes and cleaning up the mortise with a chisel. Drill-press attachments work fine for occasional use or for mortises smaller than 3/8", but most drill presses aren't designed to provide the pressure and leverage required to plunge a larger bit and chisel into hardwoods.
Be aware, though, that benchtop mortisers (and drill-press attachments) fall short when it comes to boring through-mortises. Despite our best efforts to control tear-out as the chisel/bit exits the wood, we've found the results unacceptably rough. Often, though, that tear-out will be hidden by the shoulders of the mating tenon.
How a mortiser drills square holes
Yes, you can drill a square hole with a round bit. Here's how: An auger-type drill bit spins inside a hollow four-sided chisel secured to the mortiser. The bit itself locks into a drill chuck inside the head of the machine. When you pull down on the mortiser's feed lever, the bit and chisel plunge simultaneously into your workpiece.
Like all drill bits, the auger bit bores a hole and ejects the chips. Meanwhile, the four sharp edges of the chisel pare the wood around the bored hole into a square shape. The auger bit removes this waste, as well, through a chip ejection slot in the chisel.
 Learn the results of our testing of the Bridgewood HM-11, Delta 14-651, Fisch BTM99-44252, General International 75-050 M1 and 75-050 T, Jet JBM-5 and Shop Fox W1671 when you pick the June/July 2004 issue of WOOD magazine and turn to page 78. Or, you can download the complete review, including charts and photos, for only $4.95.
Editor's Choice Top Tool: General International 75-050 T
Editor's Choice Top Values: Delta 14-651, Shop Fox W1671
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