Well, only days after installing spoilboard, someone used long, crappy steel drywall screws and busted one off deep in the table. Head's gone and shank ends about 1/4" below the surface. They tried to excavate it but only succeeded in digging a larger hole around it, but there's not enough room to get vice grips around it and needlenose don't have the leverage. It will probably destroy the resurfacing bit. It's not a situation for a broken screw extractor, that would just slide off. As would a drill. Well, I might use the CNC spindle with an endmill, but it's steel, and I don't know how long that screw is, I could end up making it harder than ever to retrieve the whole thing.

Any genius ideas for removing it? I thought of wetting the MDF (it already has a trench dug around it where they tried to dig it out). The idea being that it will turn the MDF to mush so the screw might come out, but I expect all it will do is ruin the MDF. I thought of maybe taking an aluminum arrow shaft, cutting teeth in it, and using it as a long hole saw. It's an interesting idea but I don't think the "teeth" would be strong enough. Maybe a thin-walled steel tube but I can't think of a convenient source.

Would an external stripped-bolt-removing cup work? I don't have a set of those, and this seemed much smaller than I remember the ones I have seen being. Smallest external is listed as 1/4", but I think that's the minor diameter inside (not sure), and that may be too large to grab that drywall screw shank.