Morris chairs back slat tenons

[Bob Riefer]

Hi,
I'm nearly done with TWW guild build for 2 Morris Chairs and accompanying foot stools, and it's time to cut the tenons on the back rest slats.

The slats are bent laminations, and Marc builds a form to hold them vertically while using a routing template to cut the tenons. Looks like this:

router jig.JPG


In my mind, it would be far easier to build a setup to consistently hold the laminations "level" in my table saw sled. A concave "cradle" could hold the piece to cut one side of the tenon, and a convex support block could support the laminations when cutting the other side.


Once setup, I could cut one side of each tenon quickly and repeatedly... Switch the setup and cut the other side of each. Both setups using the same stop block to define the tenon length consistently.


This seems like far less jig building, far more repeatable, much faster, and way less room for an errant router pass ruining a tenon.


Any flaws in my thinking here?


Thanks!

Bob R.

[Jim Becker]

As long as your fixture holds the workpiece securely and in the proper orientation/plane to the tooling doing the work and in a repeatable manner, you're good

[Bob Riefer]

Thanks Jim! The bending form used to construct the bent laminations in the first place can be repurposed to hold the pieces... affixed with double sided tape to my table saw sled, and clamps will hold the slats in place.

Even if there's some 'spring back' after removing the laminations from the bending form, I can correct for that once with hot glue/shims (while still preserving the form for future use).

[Jim Becker]

I would be cautious about "spring-back" from the perspective of joinery...particularly shoulders... if you use the bending form directly. You may need to release the workpiece, shim to account for the "spring-back" and clamp before making those cuts

[Bob Riefer]

Agree - that's what I was alluding to above. Whatever the spring back amount is, I'll use hot glue and shims to fill that space when I repurpose the form as the table saw sled "cradle". Afterwards, I can remove the shims so that the bending form could be used for a future chair build.

[Rod Sheridan]

I cut mine on the shaper with a sled, a table saw would require more work but should be fine

Regards, Rod

[Thomas McCurnin]

We just laid them out with a pencil and cut them by hand. Safer, and honestly more accurate.

[James Jayko]

FWIW, I've done two of those in the last year. I built the jig he built in the video and it worked out well for me. If I understand what you're suggesting, you'll be sort of doing the same thing, but you'll have to do it twice (front and back profiles). His jig was pretty easy and didn't take very long, and was accurate when I used it. Way easier if you setup two routers so you only have to mount the parts once IMO.

[Bob Riefer]

I'm close to making these cuts now and thinking more seriously about it.

What I don't like about my initial table saw approach idea is that by requiring the piece to be flipped to cut both sides of the tenon, having the shoulders match exactly, and having the tenons walls be perfectly parallel to each other, may be finnicky.

@Rod S. >>> I think your approach is the one that makes most sense to me. I have a slot cutting stack set, so my plan would be to space cutters high and low to leave the tenon I need in place, while removing both shoulders in one pass. The bent laminations would ride in a simple sled, and would be indexed by center mark, and affixed to the sled during the cut. This would eliminate piece flipping error, and be easily repeated operation for consistency.

Am I thinking about this correctly?

[Rod Sheridan]

I'm close to making these cuts now and thinking more seriously about it.

What I don't like about my initial table saw approach idea is that by requiring the piece to be flipped to cut both sides of the tenon, having the shoulders match exactly, and having the tenons walls be perfectly parallel to each other, may be finnicky.

@Rod S. >>> I think your approach is the one that makes most sense to me. I have a slot cutting stack set, so my plan would be to space cutters high and low to leave the tenon I need in place, while removing both shoulders in one pass. The bent laminations would ride in a simple sled, and would be indexed by center mark, and affixed to the sled during the cut. This would eliminate piece flipping error, and be easily repeated operation for consistency.

Am I thinking about this correctly?

Yes Bob, I did mine with a sled and tenon cutter with a spacer so it took one pass and the shoulders were perfect

Regards, Rod.