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    Fixing Woodworking Mistakes





    Last week I wrote about covering unsightly face grain with beautiful quartersawn veneer. I had carried out this technique on the legs of a Shaker writing desk I've been working on recently. Everything on that project was going along great until I realized that I had mistakenly made the mortises in my legs (which would mate with tenons cut into my table's aprons) about a 1/2-in. too long!

    A Note on Furniture Construction
    Most tables - especially Shaker tables like this one - are built using mortise-and-tenon joinery. A mortise(the hole) is cut into the side of each leg. Then tenons (the male part) are cut in the ends of the aprons, which fit into the mortises. Click the photo at left for an enlarged version.

    Now, I had worked pretty darn hard on those tapered legs, and the last thing I wanted to do was trash all my hard work, so I opted to go in for a repair on each of the legs. Here's how I fix a mortise that's too large:

     

    Fixing a Bad Mortise--Step-by-Step


    click to enlarge
    The Problem
    My mortise was supposed to be only 3-1/2-in. long. I accidentally cut it at 4-in. In order to fix this, I would have to plug up the excess negative space.

    click to enlarge
    Mortise Chisel for Sharp Corner
    To begin, I needed to clean-up the lower wall of my mortise. I wanted to have a perfectly flat, clean surface to glue my plug against. I used a small square to help align my mortise chisel and gave it a tap with a mallet.

    click to enlarge
    Chisel Technique
    With the cut started, I finished the job by using my body to bear down on the chisel and finish the cut, shaving the bottom of the bole to a nice clean surface. Notice how I hold the chisel with two hands and really bend over.

    click to enlarge
    Match the Grain
    It's important to have a good grain match to make the repair seemingly disappear. I used wood from the same stock I built my legs from and was careful to use the same type of grain for the repair - in this case, quartersawn grain with tight, straight grain lines.

    click to enlarge
    Cut the Plug
    I used a handsaw and a miter box to cut my repair piece. You could use your miter saw, but this is such a small piece of wood to cut, that it just made sense to do it by hand, at my bench. Be sure to cut it so that the plug will be proud of the surface of the leg once glued in.

    click to enlarge
    Too Tight?
    I cut a piece that fit just a wee bit too tight in the hole. To remedy this, I just sanded both faces a bit and re-fit the plug. No sweat.

    click to enlarge
    Glue it In
    I applied glue to every surface of my patch, except the top and the face that is oriented into the mortise. Then I just tapped it in with a mallet. I then placed a narrow piece of wood into the mortise and banged the patch down flush to the bottom of the mortise wall to be sure there wasn't a gap.

    click to enlarge
    Plane and Sand While Wet
    Next, I wiped away the glue squeeze-out and used a small block plane to make the patch flush with the leg. I followed up with some gentle sanding which created dust that I rubbed into the edges of the patch, thus hiding any potential glue lines.

    Ed_Pirnik