made-by-monkeys2

Good ideas with bad execution, or good execution of what should be bad ideas - an analysis of inferior, off-beat or malfunctioning products, and how other people's failures can help us design better stuff.

Bedroom lock fails to fail safe

lockblog2.jpgThanks to reader Peter S for sharing this with Made By Monkeys, an unfortunate story of failing lock mechanisms… He writes:

Last night I was trapped outside my bedroom because the latch inside the door disintegrated leaving the spring-loaded bolt engaged. So instead of going to bed, I had to get a ladder out and climb in through an upstairs window.

Armed with a screwdriver and a pen knife, I eventually managed to push the bolt back against the spring with only a little damage to the frame – much less than would have happened if I have shouldered the door from the landing.

It turned out that the lock mechanism had fallen apart inside the door in such a way that the cam could no longer push the bolt back far enough to disengage it.

lockblog4-web.jpg

If this had been a one-off, I would not be quite so miffed.

But the same thing happened to the same door three years ago and I deliberately bought this lock to avoid last time’s failure mechanism.

The earlier lock was largely made from cast parts and the bolt operating channel, which operates in tension, cracked across allowing the spring to shove the bolt uncontrollably into the frame.

That time I had just left the room without a stitch on and my wife who was trapped in side had to throw clothes out of the window so, after a daring dash onto the front lawn, I could dress and fetch the ladder and tools without being arrested.

I bought a replacement lock with a folded sheet metal operating channel which I knew would not crack, and it didn’t.

Instead the outer shell dropped apart with the same result.

Does anyone make a reliable door catch, or at least one that fails in a way that doesn’t need a ladder to fix it?

Peter S

Indeed, can any other readers supply further examples of non fail-safe mechanisms?

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3 Comments

  1. May 04, 2011 15:20

    Thanks Mark, and Jeremy. Outsourcing and sub-contracting often seem to be a curse of the modern world. A race to the bottom in terms of costs (and quality of service) and also a shifting of responsibility. Everything becomes cheaper, but so does the quality of life!

    The lock was around 50 years old so I suppose could be forgiven.

    Indeed, Jeremy, if only more things could last 50 years!
    I think these two points are related….

  2. Mark Plant
    May 04, 2011 12:17

    I bought a brand-new house with this problem on most of the interior doors. It turned out that the carpentry amongst other trades had been outsourced to contractors. One carpenter told me he could fit all 13 doors to each house on the estate (about 50 houses) in half a day each. I watched him fit a door to the back of the garage, which was on the plan but overlooked when the house was built. I was shocked at the lack of skill and poor workmanship, having worked on doors myself in the past. The problem with these types of ‘cheap’ fittings is that they must be fitted into a hole drilled exactly at right-angles to the edge of the door. Failure to do this puts adverse stress on the internal cast components, and so they fail. Fit them properly and they will give many years of service.

  3. Jeremy Stevens
    May 04, 2011 11:32

    Same thing happened to me but I was trapped inside with no tools. Luckily there were other people in the house, though it took some shouting to atract their attention. This was during the day so my neighbour’s ladder was borrowed to ferry up the necessary tools to retract the catch.
    The lock was around 50 years old so I suppose could be forgiven.
    Jeremy Stevens