An Easy Mitered Box Build with Splines - Popular Woodworking Magazine
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easy mitered box build

Here’s how I made the pair of urns in last week’s post.

Step 1: Choose your material

My client wanted to use maple for one of the urns because she’s from Canada. She also liked the idea of walnut splines. She chose the other species — cherry for one of the boxes and burly ambrosia maple for the lids — during a visit to my shop.

I wanted the grain to run continuously around each box, so I marked each board with a number to indicate the order and orientation of the parts.

easy mitered box build

Mark the parts to be cut out of the board using a system that enables you to keep track of the orientation as well as identity of each part.

Step 2: Cut the miters

I mitered the sides on the table saw using a miter gauge. I used the rip fence to determine the length of each side (in this case, all of the sides were the same length). To keep the workpiece from binding, which could be dangerous, I set up each cut with a block of scrap, then removed it while holding the piece firmly against the miter gauge.

easy mitered box build

My box sides were in effect the offcut. This made it even more critical to keep the workpiece firmly held against the miter gauge fence. The block of mahogany is a temporary spacer to ensure consistent lengths for the sides in addition to a safe cut: After setting the workpiece in place against the miter gauge I slid it up to the block, held the workpiece in place with my left hand, then removed the block with my right. I turned the saw on with my right.

easy mitered box build

Hold the workpiece firmly against the miter gauge fence while pushing it forward steadily to make the cut.

easy mitered box build

Full disclosure: The shots of mitering were set up after the fact. The blade I used for the boxes was a Forrest Chopmaster, which made extremely clean mitered cuts.

Step 3: Groove for the bottom

Next, I changed back to my Forrest Woodworker II blade set at 90 degrees and ran each side over the saw twice to create a 1/4″ wide groove for the plywood bottoms. (This step is not illustrated here.) I presanded the interior faces of the box sides, then glued them up.

Step 4: Glue up

There are different ways of clamping miters. I used lightweight clamps, applying them gently at first and gradually tightening alternating clamps until the miters were fully and evenly pulled up. Tip: I used Titebond Extend for a little extra open time.

The next morning I removed the clamps and carefully gave the boxes a light sanding to clean up the corners.

easy mitered box build

Step 5: Kerf for splines

easy mitered box build

To cut the grooves for splines I made a quick cradle that held the boxes at 45 degrees. I could easily push the cradle forward, holding the box in place while pushing the cradle forward, keeping it firmly against the table saw fence. NOTE: If you make this kind of cradle and use screws or other metal fasteners, make sure that the fence is set so that the saw blade will not cut into them.

easy mitered box build

The spline kerfs cut

Step 6: Square up those jagged kerf ends

easy mitered box build

Because all of my table saw blades leave a V-shaped point at the center of the kerf, I had to trim the ends of the notches. I started by scoring across the grain with a marking knife, using a square as a guide.

easy mitered box build

Next, I set the tip of an 1/8″ chisel in the knife mark, bevel up, and carefully tapped with a wooden mallet to remove the V. I cut about 1/3 of the way in from each side and left the little bit of wood remaining at the inside corner of the miter.

Step 7: Spline time!

easy mitered box build

After ripping walnut splines to just the right thickness, I rough cut them to a little over size.

easy mitered box build

With each spline held in a vise, I scooped out a little semi-circle of material so that the outside portions of the spline would bottom out in the groove without being blocked by the little bit of material I’d left at the groove’s center.

easy mitered box build

I cut the splines roughly to size with an old backsaw. (Here the saw is lifted to show the spline against the bench hook. Yes, I know that this is not the angle at which one should use a backsaw.)

After the glue has dried, trim the splines with a saw, then carefully plane level with the box sides. Sand the box inside and out.

Step 8: Lids

My client decided on rare earth magnets to hold the lids in place. I cut the lids with about 3/32″ overhang on all sides, anticipating that they will shrink a little in width next winter. Next, I used a 3/8″ Forstner bit to drill holes for the magnets and glued them in place with epoxy.

easy mitered box build

And there you have it.

– Nancy Hiller 

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Showing 2 comments
  • rmason

    Wouldn’t it be more efficient to make the groove for bottom before you cut the mitered sides?

    • Nancy Hiller

      Of course you can do that. Efficiency was not my goal in this case. If I were making these in quantity, I would certainly groove the stock first.

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