On Thu, 11 May 2017 15:55:40 +0200, Emanuel Berg
wrote:

Often the situation is like this. There is
a very rusty bolt with a Phillips head.
However when you rotate the nut the bolt
rotates as well. And to hold it with
a screwdriver just destroys the star pattern.
To hold it with a pair of pliers isn't possible
either as the whole thing just rotates in the
grip working off the rusty layer.
Spraying WD-50/5-56 to no avail. I would like
to replace those with M5x16s. So far I have
drilled right thru the bolt and nut to dispose
that way. Is this what you usually do?
Yes, if my "stripped head screw remover" doesn't work