more truth to that than you might expect
here are a couple of examples...
my father in law designed a jig to provide a dead flat, no-wobble platform to face turn the wheels for spinning wheels
the initial product was bored slightly oversize but more importantly off axis
one hundred pounds of iron doing what it wants to is quite frightening
he built his own the second time with the small town machinist who taught him after the war
beautiful and true....no wonky warbling sound...just the hum of the motor and the hiss of the chisel removing wood
in my work it was wood, the wood in people's homes
I was working with a tech that everyone liked but wasn't very flexible in his approach to the job
customer wanted some wire in THAT spot...period
jerry measured everything...multiple times...he always did
we went to the basement to drill up...after about 24 inches of boring jerry began to worry but he kept drilling
then a shriek
jerry had drilled up, the bit had glanced off a nail in the floor's substrate, through an oak parquet floor, through about eighteen inches of piano leg and out the top of its curve into the bright sunshine
there was an offset because the house originally hadn't been built with a basement
jerry had measured from a wall that was concealing the old footing
while she was berating poor jerry I pulled out the molding, whipped out my bright chrome yankee drill, put hole at the edge of the wall and dropped a telltale into the basement, tapped the molding back in place and went downstairs
the company bought a new floor and a new baby grand
it's not that I don't have a number of stories to tell on myself
it's just more fun to recount someone else's disasters