The secondary stretchers separate the main front and back stretchers and complete the seat frame. The next step in the project is to get those secondary stretchers cut and fitted.
First, I centered the front/back stretchers on each other and clamped them in place. This allowed me to mark the locations where the secondary stretchers will land.
With a side assembly in the clamping jig, I dry fit the the main stretchers so that I could work out the angles and length of the secondary stretchers. I used a scrap of plywood to work out the angle of the rise from the back to front stretchers.
This is the miter angle for the miter saw.
The secondary stretchers are also rotated so that they follow the curve of the front/back stretchers. There's no flat reference edge on the stretchers themselves to measure that angle of rotation, so I used a straight scrap of plywood to span the length of one of the stretchers. This will give me a reference edge for checking the angle.
The line drawn here is locally perpendicular to the curve of the stretcher.
With a square on my temporary reference edge, I could mark a second line (which would be vertical if the chair were upright). I didn't bother trying to measure the angle. It looks somewhere between 2-3 degrees and gives me a rough starting point for the bevel angle on the miter saw.
From there, it was just a series of test cuts and small adjustments to the bevel angle until the scrap stretcher was fitting in place.
Then I could cut a set of real stretchers and check them for fit.
Because of the compound angles on the ends of the stretchers, I had to tilt the fence on the Domino to accommodate the bevel angle. The off-cuts clamped on either side of the stretcher provide additional support and ensure that the Domino doesn't rock on the narrow stretcher.
With the mortises cut in the ends of the secondary stretcher, I started on the face mortises on the main stretchers. When using the Domino vertically, there's a 1cm fixed distance between the fence and the center of the Domino. I made a little 1cm marking gauge so that after marking the Domino location, I could mark an 1cm offset for the fence location.
The fence has a center line carried on to the top to sight the center of the Domino. Again, the off-cuts helped provide additional stability for the Domino.
Then I could make the vertical plunge to make the mortise on each end of the main stretchers.
A dry fit of the seat frame. I only made one just in case there was a flaw in the process. With one down, the second should be straightforward.
Thanks, guys. Splint, I must admit that the compound angles were messing with my head. I only cut on scrap pieces until I got things figured out.
Completing the second seat frame did go quicker once I realized that I could use the same bevel angle to layout the mortises in the main stretchers. With a straightedge spanning the stretcher, I could reference off the straightedge to layout the position for the Domino fence.
One of the struggles of aligning the shoe of the Domino against the fence is that the centerline engraving on the Domino is so faint. I stuck on a piece of tape and transferred the line on to the tape. Much easier to align.
Another dry fit of both chairs. I marked all the pieces for one chair with a tag of blue tape. This is just in case there are slight differences between like pieces, I know that this combination of pieces fits together well.
Having the side stretchers mounted between the front and back stretchers is an elegang solution I had not noticed until now. A neat way to make the (almost architectural looking) leg/arm elements stand out. I always fint that fitting parts like that is a bit stessfull. It needs to fint perfectly, and also it is rather thin parts that has to carry a lot of load. Good work!
"The good chair is a task one is never completely done with" Hans Wegner
Kaerlighedsbamsen commented about 21 hours ago Having the side stretchers mounted between the front and back stretchers is an elegang solution I had not noticed until now. A neat way to make the (almost architectural looking) leg/arm elements stand out. I always fint that fitting parts like that is a bit stessfull. It needs to fint perfectly, and also it is rather thin parts that has to carry a lot of load. Good work!
I agree - the ladder seat frame helps to make the leg/arm assembly stand out. The sling version of this chair has a lower stretcher between the legs, and I don't think that looks as dramatic. Fitting all of the parts has certainly slowed progress, but that means I get to work on it longer. 😁
You're right, I've had to inch through each step. The chair looks deceptively simple in structure, but has offered a number of great challenges in the construction process. I think that I should be on familiar territory when rounding the edges on the back upper stretcher. 😆
