Help with laying out curved chair back

[riverstwo]

I'm building a morris chair with the back slats curved slightly and could use some pointers on laying out the tenons on them.

The slats are glue laminated, and my original intent was to lay out the shoulders on the tenons on the end of them using the bending form itself. The pencil drawing on the bending form in the second picture below is what I had in mind.....I had planned to use my adjustable square registered on the back of the form itself to get a knife mark I could use to cut tenons that would be identical on all five slats.

......BUT, the slat sprung back a bit more than I was expecting though and I was wondering if anyone has experience with this they'd be willing to share. I'm thinking of making a second form, more like a caul, that mimics the bend as it actually settles, but I'm sure there are other ways.....

I'm happy to read about table saw sleds and router jigs, but I use my machines to resaw and dimension stock--not for much else. I'm sure something from Festool would solve all my problems, unfortunately I prefer to butcher my joinery by hand. Not trying to be a prima donna, just trying to be clear on what I need help with.

 

[Mike Davis]

I would use a long straight edge to mark both tenons at the same time so they are 180° to each other (IOW in a straight line).

If that is the chair layout...

If the tenons are at a slight angle to each other then use a bevel gage set to the correct angle and mark it from a straight edge clamped to the rail.

 

[riverstwo]

I'll give that a shot, thanks!

I would use a long straight edge to mark both tenons at the same time so they are 180° to each other (IOW in a straight line).

If that is the chair layout...

If the tenons are at a slight angle to each other then use a bevel gage set to the correct angle and mark it from a straight edge clamped to the rail.