screws
I need to repair a stripped female thread in a piece of aluminum. Originally the thread was M7x1.0. I can enlarge the hole a little, but it's close to an edge, so not as much as might be needed.
What diameter hole is needed to support an insert capable of accepting an M6x1.0 screw?
You took the wind out of my sails with that last paragraph. I was going to suggest using a nut/bolt.
As far as it causing problems when the tabletop is lowered, you can recess the bolt head. Yeah, you could make the cavity in which the bolt will stay on the underside of the tabletop, but maybe you'll drill too far or crack/scratch the tabletop if you chisel it out. It could end badly... which is why you should instead house the bolt head on the top-side of the cross member.
Brown = table top
Black = underlying cross member
The one on the left is what you were talking about. The one on the right is what you want to do.
Also, use a washer under the bolt head, etc.
If you have a micrometer, measure the outside diameter of the entry point in the barrel (illustration below)
If you don't, measure with a tape measure that will do increments of 1/32". Next, measure the depth of the barrel, and mark that depth on a drill bit that is sized to the entry point of the barrel (plus a few mm to cover the depth of the screw that goes into said barrel). Now, simply drill into the material and then screw the barrels in.
Best Answer
For one of the best known thread repair inserts, Heli-Coils, (I've used them , not associated with them otherwise) an M6x1 insert has a maximum outside diameter of 7.95mm. Data here.
A better repair in many cases would be to have a welder (person) with a welder (machine) plug the hole, then drill it out and retap it to the size you actually want. Of course, if the original part was under-designed and that lead to thread failure, making it the same as it was won't ensure that it won't fail again the same way. If it's thin aluminum you need to find a good/skilled welder. If the part allows, welding or gluing a nut to it may be a better fix for a too-thin design.