Questions about Axles

Greetings,
I’ve been wondering how I know what axle I need to get, when replacing one.
The specs usually don’t mension anything about axle length, so do I just measure the old one and then get whatever fits that length? And if so, how would I konw what length I need if I ever just lost one?
Also when do I even need to replace an axle? Do they wear out, or just when it braks/strippes?

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If you have the old one then yes, measure it and find a replacement. Most of them are M4 Set Screws that are usually 8mm, 10mm, or 12mm. It is possible to find some that are not M4 and some that are shorter (6mm), but that range covers a lot of the modern metal yoyo world.

If you don’t have the existing screw then you will need to determine the size and estimate the length. You don’t want something too long because it will damage the yoyo before it’s fully tightened. If it is too short it won’t be long enough to engage properly with the threads and either won’t screw together or will strip the threads of the yoyo.

It is rare to need to replace an axle unless the yoyo supports both a full size and a “half spec” bearing and requires two different axle lengths to accommodate the different width bearings.

Usually, if a bearing strips it will strip the aluminium body of the yoyo, not the steel axle.

Other reasons I know of to replace an axle would be if it got wet and rusted or if it got bent somehow.

Your local hardware store probably has some available for a reasonable price.

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Allright, thanks for your detailed answer ^-^

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If anyone is looking for a quick way to estimate axle length without a ruler, pick a spot and count the number of threads you see. M4 axles have 0.7mm thread pitch, so you can multiply the count by 0.7 to get the approximate length.

~17 threads = 12mm
~14 threads = 10mm
~11 threads = 8mm

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Best and cheapest way is go to the local hardware store (Ace or something like that) find one that fits and grab it. Should be under 25 cents each on the expensive side.

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As noted above, a hardware store is your friend…

Axles are just set screws, nothing magic about them. If you can’t find a set screw of the right size just buy a regular screw and cut the head off at the proper length. Smooth the cut end with a fine file.

The following is a bit dated but can give you an idea of commonly used axles.

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