Monday, August 4, 2014

Making a Tapered Chair Reamer

One of the time-consuming things about making chairs for the first time is the never-ending list of specialty tools one needs. And if I don't want to go broke, I need to make, rather than buy, most of these. So, I am making incremental progress on that front. This week, I finished up a tapered reamer, used for boring the tapered sockets for the legs.

To the best of my knowledge, the design of this reamer was invented, or at least popularized, by Jenny Alexander; there's also a good article by Peter Galbert. One starts by making a blade from an old compass saw blade. These are harder to find than 'd imagined, but I eventually found a whole box of nice ones on Ebay for really cheap. I cut the blade down to 10", ground off the teeth on the 6" bench grinder, filed the edges straight, and then ground a 70° bevel on both edges. Below shows one of the saw blades next to my finished reamer blade.

The finished blade tapers from 1 3/16" to 5/16", over 10" (more on that later).

After that, I turned the shaft of the reamer on the lathe, drilled a hole for the handle, and cut a slot for the blade. The finished tool:

I tested the reamer out on some pine. It works as advertised!

OK, so here's a slight conundrum. Nearly every chairmaker who builds these call them "6° reamers." But if you do the math on the dimensions they use, the angles are actually in the 4°-5° range. I decided to be practical about this and use the dimensions that experienced chairmakers use, rather than worry about the angles. So, this one is a 5° reamer. I think it will work very nicely.

Next up: a travisher.


  1. I guess what really matters is that the tenon fits the reamed hole. Seth Weisenecker made a nice tenon sizing tool that's mentioned on Pete's blog. Most sizing tools are adjustable anyway. Tim Manney's reamer is really nice to use, and I think it's because the blade is a bit thicker. McMaster Carr sells O1 steel blanks. Good job on the reamer!

    1. Thanks Bill! Actually, Tim was kind enough to give me the dimensions for his blades, and these are very close to his.
      By the way Bill, I had a look at the facebook page for your college program. It looks amazing! You guys are doing incredible stuff! Keep it up.

  2. Love the tool, definitely would like to make one. What are the dimensions, and the taper for the shaft. Does the blade just sit in the slot loosely?