How I made the curved chair backs
I posted a few weeks back looking for ways to make curved chair backs
for 6 cherry mission style dining chairs. There were several good
suggestions, but here is what I did:
The backs were 3" tall, and 17" long (between the tenon shoulders). I
started with a blank 1 ½" thick, and wanted a final thickness of 3/4",
which defined the limits of the curve.
I wanted an accurate template to draw the curves for roughing out on
the bandsaw, so I went to Home Depot and got two 4 ft rods which I
attached to my router base as trammel rods. I set the radius thru trial
and error to give the proper curve over 16" ( I set the start of the
curve in a ½" at each end).
I used 3/4" plywood for the template, as I had some scraps on hand. I
cut out the first curve, advanced the rods 3/4", and made a second
curve. That defined the profile of the back, looking down from the top.
I left "ears" of about 6 inches on each end. I used this pattern to
draw the curve on the blanks. I installed a new blade and retuned the
bandsaw, then cut close to the line.
I made a template for a pattern bit out of the 3/4 plywood with the same
radius as before. I made an inside curve, then added about 4" to make
the outside curve. This provided a base for the router to sit on.
Again, I left a few inches on each end for attaching to blocks and
clamping. I screwed this pattern to 3" blocks, so the blank would fit
under it. I used a 2" flush trim bit with the bearing on top to clean
up the top half of the pieces. I then flipped the pieces over, lowered
the template to be flush with the top of the backs (for router support),
and used a bit with the bearing on the bottom to clean up the rest,
using the already smooth part as the reference face.. There was a
slight problem with tearout on the inside radii, but generally I was
left with a smooth surface. Some sanding with the spindle sander and
some scraping was then all that was needed.
There was a fair amount of set up time, building the jigs, etc., but I
saved a ton of sanding and scraping from the way I did the last chairs I
built, and ended up with beautiful, smooth curves. There are details
left out, such as how to clamp the pieces for routing, but everyone will
have a different way. Save the curved bandsaw cutouts as they are
helpful in this regard. I should add that the tenons were cut before
the curves were done...
Thanks to everyone for their suggestions. Possibly this will help
someone down the line...
David