I got some chairs at an auction last week and found 3 had broken seats. I can make new seats but not sure on how to make the groove for the caning spline to sit in. Any thoughts on how this can be done with hand tools only?
Robert, I’m unfamiliar with caning, but if your third picture shows the caning spline, then the only option I can see (with hand tools) is striking a line or two (curved, if need be) to define the outsides of the groove and chiseling out the waste. Looks challenging.