I am repairing a set of antique chairs.
The chair shown here had holes for hand-weaving cane. I have done hand weaving before and it is tedious and time-consuming and not a specialty of mine.
To save labor hours I’ve excavated a spline channel on top of the holes in order to allow the use of pre-woven cane. I cut the spline channel using a plunge router and an edge guide. The cutter I used is one sold for “undersized” plywood, so it is probably 7/32”. The groove must be matched to the spline material so if you undertake this modification to an old chair, get your cane mat and spline before you cut the groove.
The cane is soaked for several hours in warm water and becomes formable to fit the spline channels. The splines have a slight tapered cross section and are wider at the top.
After the cane dries in place, I’ll remove the splines, shave them down a bit so they won’t stand proud of the seat frame, and reinstall them permanently with glue.
Cane seats last a long, long time if used as chair seats. Youngsters are sometimes undissuadable from standing on chairs and that’s how the cane seats in this set came to be broken.