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I have a number of the 32L technic axles, but most of them have some bend to them. Is there a straight-forward way to straighten these? Trying to bend them by hand has not seemed to change anything, and I'm afraid I'm going to snap them if I try harder.

  • As a side note, I'm not sure these axles were ever intended as real Technic parts and I'm fairly confident they won't handle a lot of torque (considering even shorter axles can easily twist when using a PF XL motor). – Joubarc Oct 2 '12 at 14:31
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    There's still value in getting them straight, even if it's just for the visual aspect. I might also try using them in a high-speed-low-torque application, or maybe put a bunch of worm gears on them to create a leadscrew or something. – retracile Oct 2 '12 at 17:57
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I have had some success straightening bent train level crossing gate barriers by first immersing the pieces in a bowl of hot water*, for around 5 minutes to soften the plastic and then immediately trapping them between two hardback books and applying weights until they have cooled.

So by using Joubarc's method to hold the axles straight combined with a pre-soak you may get better results.

*LEGO is plastic and plastic can melt, you only want to soften the plastic not melt it further out of shape. See this question for more.

  • I brought a bowl of water to a boil in the microwave, waited for it to stop boiling, then poured into a tumbler, then soaked the bent half of the axle in the water for 2 minutes, then "quickly" put the 32 cross-hole bricks on it and set it up as Jourbarc described, and let it sit for a couple of nights. The axle, while still noticeably bent, appears to be less bent than it was. After I've applied this technique to the rest of the bent axles, I may attempt a second application. – retracile May 14 '13 at 0:50
  • Apparently you can soften plastic dice by putting them a few seconds in a microwave (check the "Real Life" section) - maybe it would help with LEGO, but I'm not sure I would want to try it myself (especially if the warm water approach works fine enough). – Joubarc May 14 '13 at 4:17
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I'd suggest storing them straightened up for a while, if possible in 32 adjoining 1x2 bricks with cross hole, and add a few layers of bricks to hold them in place. At least it's a pure LEGO solution, but I'm not sure how efficient.

  • Do you mean this part? I could imagine that would work. If you don't have enough you could just place one at each end and at regular intervals along the way. – Ambo100 Sep 29 '12 at 13:51
  • Yes, that's exactly what I meant. I didn't have a computer with me at Skaerbaek I didn't bother adding an image or link - that's fixed now. – Joubarc Oct 2 '12 at 14:29
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    I tried this, with 32 of those bricks, and left one of most egregiously bent axles in it for about 2 weeks. I couldn't tell that it made any difference. I'll try the hot water approach next. – retracile Jan 4 '13 at 17:17
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I know that this is an old question, but I recently purchased a set with these in it, and they were bent like you describe when I took them out of the box.

Lego were kind enough to send me replacements for free.

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I got one severely curved 32L axle which I straightened with hot water in a plastic tub.

Leaving the axle in water about 70-80°C for a few minutes managed to do most of the straightening job.

Try not going much above 80°C as otherwise you reach the temperature at which ABS will start to become rubbery (used in injection moulding). At about 95- 105°C your part’s shape will be ruined because of ‘melting’.

To further straighten the axle, I repeatedly put the axle in hot water for 2-3minutes, then slightly “over-bent” the axle (to overcompensate the remaining curvature), and then keeping the axle held this way under running cold water for half a minute. This way the axle becomes rigid again, in the desired shape.

On subsequent iterations I applied the same method very locally to cancel out remaining local curvature.

Eventually the axle can be straightened enough for it to do its intended job again. It took me no more than 20 minutes.

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