Most of the nuts came out with minimal force, but the last one just spins in place. I tried rubber gloves, painter's tape, and duct tape to get a better grip. I'd rather not cut a slot in the domed nut if there's another good strategy.
The rest of the restoration underway:
There's no glue or epoxy on earth I'm aware of that will hold on metal well enough to handle the force of unscrewing a bolt.
You might solder nuts to either side, that might hold and be reversible.
The suggestions of drilling it out also won't work well, if it's already spinning in place, it will spin faster.
I know you don't want to, but cutting a slot is your best bet. If you do it clean, it'll just look like a screw. You could replace with a rivet if you really need a non-screw look for the finish
Also, I get it's a restoration project, which are fun and wholesome, but Fuck push saws.
Pull saws are where it is at! Easier to keep on target, less work, and you can't crease the blade on a cut and ruin the whole fucking saw
Though, I've never seen a pull saw you can play with a bow
I have the opposite experience with pull saws.
It might just be that I was trained on western style saws in shop class, I've used them my whole life, and I bought my first Ryoba from Lowe's on impulse this summer. But I just can't get the damn thing to behave.
I also can't find any good videos on how to use them, particularly for ripping. More than once I've ruined a workpiece because the blade was tracking straight on one side and went sidewards on the far side.
Like, do you have any tips? Because if not I think I'm just gonna cut the handle and teeth off and reuse the plate as a card scraper.
Also: Jury's out on backsaws, I haven't tried a dozuki, but I'm not convinced ryobas aren't a scam.
Hold the tip as well as the grip, and take your time. Brace it against a flat piece like you're planing it and use that as a guide.
Stick to Western saws. Got it.
This reply is the closest thing to good advice in this thread.
The only thing that's going to get that out without cutting a slot is a tack weld. Which will likely burn the wood. Just cut a slot. You can find another aged carriage bolt to replace it.