At long last, the marriage of spine and sawblade. After carefully filing all the burs from the edge of the sawblade, I set the spine in a groove in a block of wood. Then working from one end to the other, I insert the blade in the spine with a very hard rubber mallet. You have to give some serious blows to get it in, so don't be scared.
I didn't get them all to the same depth. While hammering you can see how the blade curves or stretches, depending on where you hit it. Often hitting it at the outer ends tends to straighten the blade. I stopped when the blade was deep enough and reasonably straight.
Then on to some finetuning. I had to reposition one of the sawblades in the spine (it was too much forward), like this.
To get the toothline really straight, I had to do some very carefull bending. Despite the hamfisted look of this picture, it's actually very precise.
Checking for twist in the blade.
And readjusting where neccessary. One end clamped in the vise. The other end is torqued with a clamp. I could also have used a crescent wrench or something similar, but this doesn't leave ugly marks on the brass.
And this is the harvest. I am very happy so far. This has been a major breakthrough in the project. I'll have to do some more sanding, but that's OK. Next step is filing some teeth.