2009 Kubota RTV 900, 2009 Kubota B26 TLB & 2010 model LS P7010
I have always had good luck with JBWELD but if exposed to high temps like from a plasma or cutting torch, just about any glue is going to fail. I think JAOTGUY might be on to something. The other feasible idea is to get rectangular magnets with holes in them and just attach with countersunk screws.
If you try to press magnets into a hole smaller than they are, they will crack. Magnets do not work as well when broken.
E-6000 Series Industrial Strength Adhesives. Is what I was talking about. A pocket for it to set into would be great but I have used it on 2x1x.5" magnets (8 of them) mounted on a flat surface for a magnetic mixer I built (spins at 1725 rpm) and they stayed put.
Marks suggestion of rear view mirror "glue" reminded me that E6000 works better than it does. After 3 tries at gluing the mirror onto the windshield of one of our farm trucks with the "proper" glue, only to fall off. One try with it and no more problems. I have been sold on it since '96 or so for a lot of stuff. Just not around fuel and oil, of you need a seal around them hylomar is the one I prefer.
+1 for JB Weld. But no one has mentioned the polyurethane adhesives, e.g. Gorilla Glue or Gorilla Glue quick set. Tough stuff, and doesn't become brittle, in my experience. Haven't tried it for this application, but any reason that wouldn't work?
I have a Curve-O-Mark magnetic aluminum cutting guide and it works great. You can get extensions that bolt onto it but it gets expensive. Flange Wizard sells a set of 3 magnets that have thumb screws to attach to a straight edge like a 2' square. Maybe something like that would work and you can add what ever length you want? Only problem might be that the slot for the straight edge isn't wide enough.
OK , if you don't have a full drill index ... just drill the holes exactly the size of the magnets and then use high temp adhesive ... or drill pockets to put the magnets and glue into ...