In this article it's mentioned that one very important feature of the LEGO bricks are their 'clutch power' which is "the ability of its bricks to snap together tightly while also being easy to separate, thereby readily allowing for de- and reconstruction"

Since a LEGO brick is ABS plastic and will wear with use, I wonder how many times you can assemble and dis-assemble two pieces before they no longer stay together.

  • 14
    +1 for 'clutch power' - hadn't realized it was a term used for more than the character Commented Dec 21, 2012 at 1:33

3 Answers 3


37,112 times

Well I did it. I built a machine to test this. It took 10 days until the LEGO at the bottom couldn't stay on anymore.

lego clutch tester 5000

>>> Check my blog for more details

  • 58
    Now that's dedication
    – Joubarc
    Commented Mar 5, 2013 at 10:14
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    Because there was rotation in the movement, it worn for one position but sticks a little when turned 180deg
    – pcantin
    Commented Apr 15, 2013 at 18:27
  • 4
    @pcantin lol. I saw your test posted on my local LUG site. I rushed over here to post it, but somehow, you already knew about it... Commented Apr 18, 2013 at 14:49
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    I'm riding this wave of visitors for 3 days now. This story is going around the whole net (ArsTecnica, Make blog, Arduino.cc, ... ). The cool thing for us, is that it created a massive flow of hits on our LEGO SE. I hope that many people join us on this site. What a promotion.
    – pcantin
    Commented Apr 18, 2013 at 15:11
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    @pcantin I think it would be very interesting to try out your device on a cheaper LEGO imitation brand brick and see if the brick wears out with significantly fewer repetitions.
    – ulmangt
    Commented Apr 19, 2013 at 2:00

The optimal clutch power is attained after 8 to 10 couplings(search for "clutch"); that is, before that, the bricks will sometimes cling a little too much on each other.

However, I don't think anyone ever actually stated when clutch power would start to deteriorate. I'd tend to assume that once the optimal clutch is reached, there is just enough plastic at the coupling to make it work, but not enough that it would wear of.

Of course, as you said, I suppose there is still a little that wears off, but I'd wager it isn't that much, and it's probably negligible with regards to the manufacturing tolerance of the bricks. In other words, you're more likely to find two bricks which come loose too easily because they're at the limit of the tolerance, each at a different extreme; than to take two bricks with normal clutch power and try to wear them off so that they too come loose easily.

Then again, I don't think it's ever been extensively tested. We'd need two bricks, and a robot that assembles/disassemble them a great many times. (Unless you want to do it manually)

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    I have to say that, unless there was already data available, my plan was to build a robotic rig to test this.
    – pcantin
    Commented Dec 21, 2012 at 13:54
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    You must start this right away and give your results! Commented Dec 23, 2012 at 1:31

I'm not sure there's any official answer for this, however I can answer with an anecdote.

There have been a few times where I've come across old bricks that have been assembled together for a very long time (ie many years). When prised apart, I've spotted that the studs have actually made an indentation on the sides of the tubes.

Based on this, I wonder whether there's more danger of bricks losing their clutch power from being assembled (which means they're in compression) for a long time, rather than being repeatedly assembled and dis-assembled?

  • Good points but, for this one, I'm focussing on the mechanical wear instead of the ageing effects
    – pcantin
    Commented Dec 21, 2012 at 13:57

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