More Messing with Tapered Tenons

My plans today were to get the legs onto the stand that I’m building. Things did not quite go according to plan. The first impediment was that I haven’t been too content with the way you use the tenon cutter, and it came to a head today. I prefer to twist the stock into the cutter rather than twist the cutter around because it’s easier to keep it centered that way. Unfortunately, it’s not really easy to put the tenon cutter into a vise or something to keep it put. Not like it’s easy to twist the cutter, either, mind you.

So I picked up a squared-up ash cutoff, put a rabbet into one edge, and screwed the tenon cutter into the opposite edge (it has holes and little half-moonish registration standoffs to help with the attachment):

Then I can just put it into the vise, with the rabbet registering on the benchtop. The result is that (in theory, at least), you can hold the stock parallel to the benchtop and bench front to keep it in the right place:

With this system in place, I was still having problems. The tenon cutter isn’t large enough to engulf the whole octagonal profile of these legs. I was doing a rough shaping with the drawknife and saw rasp to get a cylinder to shove into the tenon cutter, with a little transition area to the outer surfaces. I determined that you need to be fairly precise about the size of that cylinder. I’d made it too small, which resulted in tapered tenons with a long rough unshaped area between the tapered part and the transition to the octagon:

This happens because the transition area eventually meets the end of the tenon cutter and cannot advance any more. This wouldn’t happen if the tenon cutter were larger than the stock being worked (which would be the case for most cylindrical legs), or if I wanted to do a more gradual transition (assuming that I were actually good enough with a drawknife to do that). Even though this 9/16″ version isn’t the largest tenon cutter that Lee Valley offers–the 5/8″ keeps selling out too quickly–it wouldn’t make much difference here.

I decided to cut new transitions farther back in the stock and make newly-shaped cylinders bigger in order to bring the tapered part closer. Something tells me that this would be a lot easier with a lathe, but I don’t have one of those. I’d been putting it into my tail vise and just whacking away with a chisel, but the end would keep sliding around too much. So I interrupted myself again and made a stop with a mouth on one end that I could secure into two dog holes (to keep it from swiveling around):

This worked. As a bonus, you don’t need to secure it with the tail vise this way, making it really easy to turn the stock around so that you can work on all of the facets.

With this aid, I was able to shape everything a bit better and use the tenon cutter again. This made for a much nicer result:

I’m not worried about the 1/4″ between the transitions and the tapered part (this is the distance between the tenon cutter’s blade and its end).

Unfortunately, I spent so much time fooling around with these little shop aids and trying to figure out the best way to use them that I didn’t have any time to ream the holes for these things today. Oh well.

4 thoughts on “More Messing with Tapered Tenons

  1. Have you thought of making your own tapered cutter? if you have the tool to cut the female part, using an old planner blade as the cutting iron, any size you need is easy to make and it is not beyond it to put a right angle cutter to make the shoulders


    • It’s a possibility, but I think I’d tackle that upon getting more experience with tapered tenons in general. I have the general feeling that I have no idea what I’m doing with them right now.

      Your suggestion to put a right angle cutter to make the shoulders is an intriguing one. It seems like the kind of thing that I could add to my tenon cutter mount right now without (perhaps) too many problems.


  2. Late to the party here but saw this link while reading about your day bed.

    Richard is right. Making your own cutter using the blade from this one will allow you to get up to shoulders on your legs. You already have the reamer so the angle in your block will match. Looking at the metal LV shaver the blade is far from the end because the “ring” of metal to reinforce the casting is in the way.

    It probably doesn’t matter since once the shoulder is on the mortised hole the taper is no longer doing its job. The straight section will only comprise a small part of the joint.


    • I’m guessing that the “straight” section doesn’t matter much, especially because you want the shoulder to be a little bit of a distance from the end of the mating mortise, but we’ll see. I might get back to this in a few months, and could experiment with it then.


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