The drilling jig in use. I cut some more notches in it after this photo was taken, which are shown in the drawing.
I am fairly jig-averse. Not because of some philosophical reason – it's just not the way my head works. When I look for solutions to problems, "making a jig" is way down on the list.
But sometimes, jigs are the only way forward. Last week I taught my first-ever class in making Gibson chairs. I was an emotional wreck the whole time, trying to keep seven students on track while I revised my lesson plan. But everyone ended up with a nice elm Gibson chair.
In my recent video on making the Gibson chair, I use the same drilling jigs for the Gibson that I use for all my chairs. But when thrown into a classroom environment, the old jigs were too finicky and required too much setup in order to get the arm positioned in the correct place over the seat.
So I went into our machine room for 20 minutes and devised the jig shown here. I'm sure it can be improved, but for now I'm thrilled with how simple and repeatable it makes the process.
It is made from 2x10s from the home center. Here's a cutting list:
1 Front piece 1-3/8" x 8" x 14"
1 Back piece 1-3/8" x 8" x 17"
2 Top stops 1/2" x 1/2" x 6"
1 Bottom stop 1/2" x 1/2" x14"
Screw the front piece to the back piece in the T shape shown above. Glue and nail the top stops to the top edge of the front piece. Glue and nail the bottom stop to the underside of the front piece. Done.
Now you need to set up the jig so it can be used over and over. Place the jig so it is centered between the mortises for the short sticks and long sticks. Mark on the jig the location of where the seat meets the jig. This allows you to put the jig in the right place every time.
Place the arm on the jig and position it for drilling (as shown in the video). The top stops put the front of the arm in the same plane as the front of the seat. Shift the arm so it is in the correct position over the front mortise (the inside edge of the arm should be tangent to the center point of the mortise on the seat – also shown in the video). Then rotate the arm so its rear mortise is directly in line – a 0° sightline) with its mortise in the seat. I do this with a laser in the video.
Now trace the shape of the arm on the jig. You just made the process repeatable. Shift the jig to the other side of the seat and repeat the whole process for the chair's other arm.
View the model here.
https://app.sketchup.com/app?3dwid=3b50693c-69e2-4bba-aeb9-75c3166b38b9
You can download a SketchUp drawing of the jig at the 3D Warehouse for free.
— Christopher Schwarz
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