Canadian Woodworking

One divider, preferably with joinery

Blog by Rob Brown

A wise woodworker once said, “The difference between a good woodworker and a bad woodworker is their ability to fix their mistakes.” There is definitely some truth to this, although I don’t think this is the only difference between these two types of woodworkers.

A wise woodworker once said, “The difference between a good woodworker and a bad woodworker is their ability to fix their mistakes.” There is definitely some truth to this, although I don’t think this is the only difference between these two types of woodworkers.

Mistakes happen, whether in woodworking or in any other part of life. How we deal with them is critical. I don’t like it when I carefully consider a tricky order of operations only to find out down the road that I should have done something differently. What I truly dislike is making silly mistakes that should have been easily avoided. That’s exactly what happened to me the other day.

One divider, preferably with joinery

While making a three-door sideboard I decided to add a divider to the interior of the case to add structural rigidity to the piece. It was a fairly straightforward design; the divider, with 1/4″ x 1/4″ tenons on both its ends, would be held in place by grooves in the top and bottom of the sideboard.

I set up a router with a straight bit and aligned and clamped a straightedge to the workpieces to machine the 1/4″ wide stopped grooves (the divider wouldn’t be visible when the doors are closed, so the divider was made about 2″ narrower than the gables), machined them, measured for the divider length, then cut it to size. I had literally just finished cutting the divider to length — the saw blade still spinning — when I realized I didn’t account for the 1/4″ long tenons on both ends of the divider. I immediately threw my hands up in the air and let out a groan. Just a silly mistake, very likely caused by the fact that I was moving quickly around the shop, making great progress on this project, and didn’t think the entire situation through.

I find it really frustrating when I just don’t see something I should and make a mistake. One option was to cut a new divider, but the 3/4″ black walnut plywood I was using was all accounted for, and the thought of forking out another $190 for a sheet didn’t make me feel any better about my mistake. I could cut the gables 1/2″ shorter, though the amount of machining I had already done to them made that prospect not too appetizing either.

Another option was to run a mating groove on the ends of the divider, glue in a piece of 1/4″ thick plywood to extend from the divider’s end by 1/4″ and have that be the tenon to fit the grooves already machined in the top and bottom. The only problem with that option was that 1/4″ thick plywood is thinner than 1/4″ and wouldn’t fit the grooves well.

If strength was of critical importance I would have gone with this last approach and made a 1/4″ thick floating tenon that could be glued into the ends of the divider and mate with the grooves nicely, but I didn’t actually need to stop a speeding bullet with this joint. I needed this joint partially to assist with location during glue-up, and partially for strength. I also knew I could add a few screws and dowels through the underside of the case, up into the divider, and also add a pair of 3/8″ x 3/8″ glue cleats to the upper divider / top joint to add some strength. The cleats would be low enough so they wouldn’t be seen.

In the end, I went for a slightly different option. I machined a piece of solid wood and glued it to the ends of the dividers. The strip was ever so slightly under 1/4″ thick (so it wouldn’t bottom out in the groove machined into the top and bottom panels) and about 7/16″ wide. When dry, I could machine the solid wood strip into the tenon and proceed with final assembly.

Good enough

It wasn’t the strongest solution, but extreme strength wasn’t what I needed. I was looking for “quick” and “good enough.” I glued on the two strips, did a few other things for an hour, then was able to machine the tenons on the ends of the dividers and assemble the cabinet. I probably spent almost as much time considering my options as it took me to actually fix the problem.

Just happy accidents?

A mistake forces you to step back and look at the situation as a whole. There are some times that when doing so you come up with a design or construction idea that’s even better than what you initially planned. You hear this from fans of the American painting icon Bob Ross, who said, “We don’t make mistakes, just happy accidents.” Maybe this is true for oil on canvas, but I find it’s rarely the case when I’m working in my shop. When I make a mistake, I know it. And there’s rarely anything happy about it.

What’s the biggest woodworking mistake you’ve ever made? If you’re trying to put it out of your mind, I understand. But if you’re not still frustrated by your oversight, comment below. Hopefully, the equation will always be mistakes + time = humour + learning.

Glue a New Piece On

Clamps and cauls are used to apply pressure to the small tenon strips to both ends of the dividers.

Ready for “Tenonizing”

A strip of solid wood, ready to be machined into a tenon.

A Good Fit

After my dado set brought the tenon to a near fit, I adjusted the tenon’s width to fit the grooves with a shoulder plane.

All Done

The new black walnut tenon in its final resting place. With some screws added from below and a couple of glue cleats added at the upper joint, the divider will stay in place for a long time.

Last modified: May 15, 2022

Rob Brown - [email protected]

Rob is a studio furniture maker and the editor at Canadian Woodworking & Home Improvement. Instagram at @RobBrownTeaches


  1. hey rob , i asked this of canadian woodworking in the past and i will ask again today, do some articles building from plywood and 2x lumber. not all woodworkers work with or can afford grade “A” lumber.

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