Turning eight matching spindles for a broken chair
A kitchen chair with a broken stretcher turned into a project to replace all eight spindles in the back, because once one was out it was clear that three others were cracked and the rest were loose. The originals were birch, 38 cm long, 16 mm at the thickest point with a taper to 12 mm at each end and a decorative bead and cove about a third of the way up. I had never tried to turn eight of anything the same.
The first thing I learned was to make a story stick. A strip of thin plywood the length of the spindle, with every transition point marked on it with a pencil line and a note of the diameter at that point, measured from the best original with calipers. Transferring the marks to each blank with the lathe running and the stick held against the wood takes ten seconds and removes the guesswork. I also set three pairs of calipers to the three critical diameters, 16 mm, 14 mm and 12 mm, and left them set for the whole job.
The blanks were birch from a plank, cut to 25 mm square and 42 cm long to leave waste at each end. Roughing to a cylinder took about three minutes per blank with the roughing gouge at 1800 rpm. Then the story stick marks, then a parting tool at each mark to the caliper depth, then the spindle gouge to shape the taper between the marks, then the bead and cove with the small spindle gouge and the skew. The first spindle took 45 minutes. The eighth took 14 minutes. Numbers two and three were the worst, because I was rushing to beat the first time and got careless with the skew on the bead.
Matching turned out to be more about the transitions than the diameters. The eye forgives a spindle that is 15.5 mm instead of 16 at the belly, but it notices immediately if the bead is 5 mm higher on one than its neighbor. The story stick handles that. The eight finished spindles, lined up on the bench, vary by about half a millimeter in diameter and nothing I can see in position. The tenons are 12 mm into 12 mm holes with a smear of glue, driven home with a mallet, and the chair has been sat on daily for a month without a creak. The broken originals went on the firewood pile, where their descendants will join them in due course.