Been thinking about mortice and tenon joints
A while ago Brian Boggs spoke about developing his tapered tenon joint (you can read a bit about it here)
At the time the mention of custom made router bits put me off, but I recently noticed that Wealdon do have 2.5deg tapered bit in their standard range (for mould making). Not quite the 3deg that Brian was using but close enough to make it feasible if you are cutting your mortice and tenons with a router anyway (FMT, pantorouter, CNC or shop made jig)
But is tapered better?
I have certainly learnt the benefit of tapering for sliding dovetails, which make assembly so much easier
However for a tenon the practice is almost to go the other way, especially on critical joints like in chairs. I've used wedged through tenons, where you flare the exit side of the mortice with the very intention of creating a wedged joint that cannot pull out even if the glue fails. However it is true that round mortice chair joints are tapered and then wedged from the top, so you can have both!
I guess my concern is that a tapered mortice and tenon might assemble easily and reduce glue starvation/wipe off (if that is a thing), but as soon as the glue fails or tenon moves a little it will fall apart. I was taught good joinery assumed the glue will fail eventually - is that still a thing with modern glues?
I respect and admire Brian Boggs, his furniture and his generosity in sharing ideas and techniques of the craft with us. Is the tapered tenon something with wider application or is it a niche application for his amazing chairs only?
A while ago Brian Boggs spoke about developing his tapered tenon joint (you can read a bit about it here)
At the time the mention of custom made router bits put me off, but I recently noticed that Wealdon do have 2.5deg tapered bit in their standard range (for mould making). Not quite the 3deg that Brian was using but close enough to make it feasible if you are cutting your mortice and tenons with a router anyway (FMT, pantorouter, CNC or shop made jig)
But is tapered better?
I have certainly learnt the benefit of tapering for sliding dovetails, which make assembly so much easier
However for a tenon the practice is almost to go the other way, especially on critical joints like in chairs. I've used wedged through tenons, where you flare the exit side of the mortice with the very intention of creating a wedged joint that cannot pull out even if the glue fails. However it is true that round mortice chair joints are tapered and then wedged from the top, so you can have both!
I guess my concern is that a tapered mortice and tenon might assemble easily and reduce glue starvation/wipe off (if that is a thing), but as soon as the glue fails or tenon moves a little it will fall apart. I was taught good joinery assumed the glue will fail eventually - is that still a thing with modern glues?
I respect and admire Brian Boggs, his furniture and his generosity in sharing ideas and techniques of the craft with us. Is the tapered tenon something with wider application or is it a niche application for his amazing chairs only?
