Turn Accurate Tenons with a Modified Wrench
A lot of people use open-end wrenches to check the size of turned tenons. I’ve taken the idea a step further. I sharpen one jaw so that it can remove stock and size tenons in one step. Starting with yard-sale open-end wrenches (here in the UK we call them spanners) in the tenon sizes you need, slowly grind a 30° cutting edge on one side of the jaw, dipping it in water often so you don’t overheat the hardened steel and draw the temper.
To use it, turn the tenon slightly oversize with a regular turning tool. Then switch to the wrench and adjust the tool rest to support the wrench’s neck. Lay the wrench against the tool rest and touch the lower jaw to the work first. Slowly press forward to start cutting. When the tenon reaches its final size, the tool will slip onto the tenon and stop cutting. Leave the wrench on the tenon for a moment to burnish and slightly compress the wood fibers. When you apply glue to the tenon and put it in, the fibers will expand again, locking the joint tight.
Ian Welford, Sinderby, None