To make the conical mortise for a piece of staked furniture, I first bore a hole that is the smallest size of the overall joint – typically 5/8” in diameter. Then I follow that up with a tapered reamer that turns the cylindrical mortise into a cone-shaped mortise.
There are lots of good ways to do this. Here is the method that suits my tools, head and hands.
I make the 5/8”-diameter mortise with a brace. You can do this with a drill press with an angled table or any other boring tool. But after trying many methods during the last 11 years I have settled on making the initial hole with a brace and an auger.
I sight the drilling angle against a bevel gauge that I tape or clamp to the underside of the seat. As long as I sight against only one angle (what we call the resultant angle), then I can get within a fraction of a degree with this method.
Like with all good augering, I reach below the seat to feel for when the auger’s lead screw pokes through on the exit side of my hole. When I can feel the lead screw, I flip the seat over and finish the mortise from that side.
That’s the easy part for me. For many years I struggled with reaming. When I used a brace I tended to create an elliptical mortise, which is no good. After much practice, I still made a wonky mortise. I know other people do this operation with ease, but it’s out of my hands, apparently.
Then I tried reaming with a cordless drill that was set to a low speed and maximum torque. For some reason, this fixed my mortises. Instantly. Perhaps I’m suited to focusing on the direction of the cut while the drill supplied the round-and-round.
I’m not saying this is the best way, but it’s something to try if you have the same problem.
First-time chairmakers often confuse the terms “rake” and “splay” – and never mind the other names for the other angles in a chair.
After I took my first chairmaking class 11 years ago, I made up this little explanation for myself so I wouldn’t forget.
Chairs are like saws.
When you look at a saw from the side, you can see the teeth raking forward or backward (depending on the filing). When you look at a chair from the side, you are seeing the rake of the legs. And chair legs can rake forward or back – just like sawteeth.
When you look a saw from the front, you can see the teeth bent out from the sawplate. This is called the set. When you look at a chair from the front, you can see the legs splay out (they never splay inward that I know of). “Set” and “splay” both begin with “s.”
OK, it’s not the most perfect explanation, but it has prevented me from mixing up the terms for many years now.
The nice thing about geometry (aside from sitting next to Cris Titsworth) is that you can perform some operations that look difficult with surprising ease.
For example, let’s look at my “wireframe” model for my next project. With needlenose pliers I can adjust the rake and splay of the legs, which are made from 12-gauge wire, until I’m pleased with how the legs look from all directions.
Then, using some formulas picked up from old books (see above, I can’t believe I am showing you this)…. I can dial in my angles.
Then it’s a cinch to knock out the finished piece:
Of course, I can adjust the legs to produce these simple variants.
Or, by simply changing the value of X, produce this: