The back legs on Chair 2 of this chair making journey came out of the plank just like you see in the photo above; nested and flipped end for end. I kept one long edge straight on each so that I had a good reference for cutting the slot mortises for the back. I'm expecting some movement of the wood after I cut the second curve on each leg, but it should be negligible.
I first laid out the mortises in the back leg for the back seat rail and the back stretcher, and cut them on the slot mortiser as shown below.
After completing all the side mortises on all four legs, I cut the final leg shapes on the band saw.
For a consistent shape of the leg profiles, I paired them up in the vise and shaped the curve to the layout lines marked on the outside of each leg.
There are a total of twenty mortises in the four legs for tenons, plus six dowel holes. Below, I'm cutting the slot mortise in the top of the back legs to receive the crest rail.
Here's a close-up of that mortise being cut. With all the shavings clinging to the leg and X-Y table by static charge, I can tell it's still wintertime!
Next it's time for the tenons to be cut on the back seat rail and back stretcher.
After cutting the tenons on the table saw and band saw, I marked the parts with their final shape using the templates I made earlier.
I then hand fit the tenons to the mortises in the back legs. I checked the flatness of the dry-fit parts frequently while fitting the tenons so that I could prevent twisting of the assembly. Success!
This is where the unique power of SketchUp came through. After marking and cutting the top and bottom shapes of the back seat rail, I then traced the templates for the front and back of the rail. The template shown below represents the curved surface in the 3D computer model that is then "flattened" prior to printing. I then transferred the curves of the top and bottom to the front and back. Now the top, back and bottom of the rail are all fitted with curves.
Here's a preview of the assembly. I have more shaping to do, but I'm getting close.
Now a bit of edge softening with the spokeshave.
The focus next week will be on the final shaping and surface preparation of the back assembly, and with good fortune, the first glue-up.
Hej då and happy shavings!
Craig Johnson is a fiscal year 2012 recipient of an Artist Initiative grant from the Minnesota State Arts Board. This activity is made possible in part by a grant from the Minnesota State Arts Board, through an appropriation by the Minnesota State Legislature and by a grant from the National Endowment for the Arts.
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