Hollow-chisel Mortiser in Action

Hollow-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:

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

– Robert W. Lang

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