How to Turn a Perfect Tenon
George VondriskaMortise-and-tenon joinery is one of the most reliable we have, but if your tenons are not sized properly or they are inconsistent, it can be difficult to assemble your projects. Master woodworker George Vondriska reveals a shop trick that you can use to turn a perfect tenon for your woodworking projects.
I'm working on a spindle for a chair. So, what's going to happen when this is all done, I've got to have a tenon on each end that perfectly mates into a hole I drill in the chair itself. Wanna make sure I have a good fit, chairs take a lot of abuse. So, I need to make sure that when I turn the tenon on the end of this, it's going to perfectly match the hole I drill in the leg of the chair. One way I could do that would be using my parting tool and my calipers, I can set the calipers to that diameter, carefully test as I go.
I'm going to demand a little bit more accuracy on this. I want to make sure I have a great fit. So, the way I'm going to do it is using this block of wood. What I've done here is took a full-sized block drilled into it a one inch hole. Then, I cut the block in half.
So now I've got kind of a go/no-go gauge for my tenon that I'm working on here. I've labeled it as one inch, so when I use it for other projects, I already know what size it is. The way I'll use it here is make cuts, test the fit, make cuts, test the fit until I get this diameter on my spindle down to a point where this perfectly straddles that material. Here's how it works. That's a perfect fit, I know that that end is going to go right into the one inch hole I'm gonna drill in the leg, it's going to be very, very strong 'cause I'm going to have a great mate between the tenon and the hole.
Remember, as you're dialing into that final, final size that when you cut, you're taking off twice the amount of wood you might think you are. In other words, if I'm peeling off a 32nd from this side I'm affecting the overall diameter by a 1/16 of an inch. So very, very light passes at the end to sneak up on that final setting. But this is a very easy way to make sure it's dead accurate.
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We, in England (UK) use the correct size open mouth spanner to do these types of jobs they work exactly like your wooden template but with out the work of making a wooden test piece. We check the exact size of the drill bit we would be using by placing it into the jars of the spanner that way we know the hole and tenon will fit exactly. This way it's less work and a lot faster. Ps it is possible to use a adjustable spanner providing you can lock of the adjustable mechanism. By engineering a thumb screw. The easiest way is to use duck tape. Pps The safest way is just to use a solid open mouth spanner. Regards Ian M Chadwick
IMHO, a digital caliper should work better (up to a diameter of about 3"). It would allow you to see how far you need to go and would check the diameter along the tenon's entire length. A slightly tapered shape for the tenon might also work better when the hole isn't perfect. And remember that you can't fit a 1" dowel into a 1" hole - either the dowel needs to be slightly smaller or the hole slightly larger.
just a query on tool hieghts on the video