How To Make A Thick Countertop Out Of Thin Wood
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Lately, I have had a run on countertop orders. They have all been walnut (which is the hottest wood around right now), and all 1-1/2-inch thick. These jobs could be as simple as gluing up boards 1-1/2-inch thick and going home. But in a recent case it wasn't that simple. 

That's because a customer ordered a large island top to be made out of their small walnut tree. The problem: there wasn't enough lumber available in the logs to cut them thick and still get the coverage I needed. 

So I pulled out a trick that I “invented” years ago when I had a similar situation with lumber that was too thin for the job. In that first attempt, I reassured myself that I could do it because the room it was going in had little light and no one could look at it closely anyway.

The concept is simple, but until you see a finished piece you may be as skeptical as I was on my first one.

It all starts with picking out the lumber and laying out the boards to be about 1-1/2 inch to 2 inch wider than the finished piece on all four sides. For the countertop, the finished size was 42 inch by 96 inch, so my final glue-up was about 46 inch by 100 inches. After the top is glued up and sanded, it is time to lay it out and trim it to the final size.

As you trim the top, keep track of the offcuts and their relationship to the countertop. All of these pieces will be flipped under the top to make up the extra thickness, and they need to line up with their original position. Start with the end grain pieces because they are the most critical as far as alignment goes.

Miter the corners, flip them over and glue them on. This will make the edge of the countertop look nice and thick.

Gluing The Pieces

After gluing the end-grain pieces, do the same thing with the long-grain pieces. The grain alignment is less critical on these pieces, so focus more on the fit of the miters and making sure that the corners look good.

After the glue is dry on all of the edges, it is time for more sanding. I use a 6-inch random orbit sander for this task. Spend enough time sanding to make sure all of the saw marks are gone on the edge. If you are doing a top with a square edge, it is time to do the final overall sanding and finishing.

The top I did got a profiled edge, which helped hide the glue lines even more. After profiling the edge, just a little more sanding finishes up the woodworking portion of this top.

When finishing walnut, I usually put on a coat of walnut stain. It is a 50/50 blend of Minwax Special Walnut and Minwax Dark Walnut to maintain the dark color, since walnut lightens with age. The stain does a great job of enhancing the rich color without hiding the grain. Waterlox, which is easy to apply and repair, was used as the topcoat.

 

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