A great story, but googling 'knowing where to tap' brings up a huge range of versions – usually boilers in a big ship or building.

It seems the original story had Henry Ford as the client. This is interesting:

answers.google.com/answers/threadview?id=183998

The rest of Us know it gets hit many times, some in anger!

I came across a true occurrence of the hammer story. Many years ago, when my first wife was a student at Newcastle, one of her friends had an old car.

One morning the starter went clunk and jammed. Suzanne trotted round the corner to a nearby workshop (there was one round every corner in those days) and came back with a man in filthy overalls who brought a hammer.

He slid under the car, fetched the end of the starter spindle a whack with his hammer, emerged and started the car.

When he asked for a £1 (which was worth having in those days) she remarked that he only hit it with a hammer and got the classic reply "but I know where to hit it".

I was with a friend once and had to call round to one of his friends that I had never met. They were standing round their television which kept flickering on and off. I asked for a tape measure and proceeded to find a spot on the case. I then gave it a sharp knock at the point I had measured and the television stopped flickering and worked perfectly (and continued to do so for some years)

To say they were amazed was an understatement. They still talk about it now. I knew that there was a possibility that a sharp blow would temporarily sort it out and the tape measure was just showmanship but they didn't!

David

Friend of mine had his laptop stolen from the boot of his car. The police showed him a very small ding in the boot lid by the lock. Apparently on that make it was a known problem that the mfr hadn't bothered to do anything about or warn the owners.

Old valve TVs were often fixed with a thump. Boards with lots of DIL in sockets also respond well to a knock or pressing the chips into their sockets for the same reason – poor contact/oxidation/creeping with changes of temperature.

looking at the picture – anyone who can fix that bearing by tapping it with a hammer is probably worth 10K/hour

Mark

That brings back memories of a sesimc survey of chalk grassland when I was a student. The 'explosives' were a large chunk of steel plate and a sledge.

Neil

I though that experience means that you know when you're making the same dumb mistake again.

* Danny M *

One of the best was watching a student catch a black hot rivet thrown to him with his hands when every one else lifted up their leather apron to catch it. I can recall the Blacksmiths name, 'Blubber' Lay, a big jovial man well suited to being a Blacksmith. Calloused hands and one finger missing.

Which of the American astronauts was it who, having fixed a vital piece of machinery by giving it a thump (in just the right place, of course), described the technique as "impact engineering"? It's a description of the technique which has stuck in my head for over 40 years.

Jeff

You have me a little worried.

One of my (Oriental) lathes has a manual which describes it as a "Percission Lathe". I had thought this a typographical error but now wonder if it is an abbreviation for "Percussion Precision Lathe", i.e. keep bashing it until you achieve the required level of accuracy!

Pero