Hollow-chisel Mortiser in Action

mortising1123Hollow-chisel mortisers are one of my favorite tools. When mortising machines were first invented, a drill bit and a chisel were mounted side by side. Ralph and Robert Greenlee changed all that, and production woodworking forever with the invention of the hollow chisel. It’s quite an accomplishment to drill a square hole, and while the device is simple, the relationship between the bit and the chisel is critical. If there isn’t enough space between the two at the pointy end, chips can’t exit and friction makes them burn and smoke. I wrote about mortises in general in the February 2014 issue of Popular Woodworking Magazine and hollow-chisel mortisers in particular in the November 2013 issue.

I was going through the photo files on my computer this morning and noticed as I scrolled through the images, I was getting a good view of how the chips come spilling out of the slot in the chisel. In print we’re stuck with static images like the photo above. Online we can animate things and come up with moving images like this. When the chisel is sharp and set just so, you should see something like this:

mortising

If the image isn’t moving, click on it.

– Robert W. Lang

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5 thoughts on “Hollow-chisel Mortiser in Action

    1. Robert W. Lang Post author

      Back in the Spring 2007 issue of Woodworking Magazine we tested different brands of chisels, and a quick survey this morning of online sources suggests that not much has changed. These chisel/bit combos (as well as the machines) shows the triumph of marketing over common sense. Most sellers offer two choices. The choice is a set of 4 chisels and bits for $50-$60. These are made overseas and work well if you tune them up following the routine listed in the other post. The second choice is to go “premium” for about $40-$50 per chisel. You don’t necessarily get what you pay for.

      What we found was that there wasn’t much difference between brands or between “economy” and “premium” either in performance or longevity. If you don’t mind sharpening up the chisels when you get them, most of the inexpensive sets are just fine. If you don’t want to fool around with an initial sharpening, the premium set from Lee Valley are a cut above out of the box, but eventually you’ll need to hone them as well. In any case, the diamond honing cones are a good thing.

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