After carefully storing my headphones in the original case for the last 4 years, never taking them on holiday incase I lost them, I take them off my head to notice the swivel mechanism at the cup seems to have cracked into a few pieces. On close inspection it seems the crack surrounds the self tapping screws close to the cover plate. Am unlucky or is this a common fault? Thanks
i havent seen plastic crack from age in quite a long time.
i know i have seen plastic literally snap in two from age, but that isnt nearly the same as seeing cracks forming around a screw.
plastic chairs used to crack around edges and screws, that was the most common place i ever seen it.
i had a plastic tab break on my moon chair.. preventing me from using the chair at all.
the broken leg stick up into the fabric of the chair.. so if i sit on it, then there is going to be a rip in the sewing, or a rip/hole in the fabric.
i have had a terrible time finding some glue to repair it.
first i tried jb quik that is supposed to be strong like a rock.. didnt work.
then i tried some 'plastic weld' that is supposed to be strong too.. didnt work.
next i am going to try to melt some new plastic into the plastic piece with a portable propane torch.
i suppose i really dont care if i have a big glob of plastic when i am done.. as long as it holds.
i dont see why you couldnt use some jb weld or jb quik
i think there is a joke about jb quik..
i have used the same stick to stir up some on more than one occasion.
and that thing has sat around for months.. if i bite on it, i cant put a dent in it.
maybe 24 hours wasnt long enough to wait.
i guess it is 24 days i have to wait.
cracks usually occur when one of two things happens:
1. the plastic shrinks and gets soft.
2. the plastic has been shrinked in the cold, and expanded in the heat.. and the going back and forth has caused the plastic to soften.
if you put just a little bit of glue in the crack.. with more time, the plastic could crack again in different places.
i'm not saying dont do it.. because repairing the cracks with glue one at a time could keep the headphones useable.
plastic sculpting and repair is bound to be a hobby for some people.
the only problem is.. if you rush into it and dont realize what type of plastic it is..
you could mix two of the opposite types of plastic and the bond doesnt hold at all.
there is some plastic that can get hot and become soft enough to bond some plastic to it.
and sometimes the plastic will 'sweat' and an oil or whatever will totally ruin the bond and it will pop apart with a slight tug.
you try to get the plastic hot and it becomes very brittle, as if it evaporates away and becomes useless .. needing a serious hole patched.
you try to get the plastic hot and it burns like cellophane.
basically this stuff gets hot and shrivels up really fast.
maybe they will tell you it was because of too much heat or too much cold or too much humidity.. or not enough.
maybe they will tell you it is because of something heavy laying on the headphones.
you layed them down with the swivel shoved to one side and it sat like that for too long.
hopefully you get a straight answer.
the only options are to fix the cracks with glue.. as if you putty it in like a dent in drywall.
they offer to sell you a new plastic piece.
maybe they ask you to send them the headphones to let them fix it.
superglue, or some other adhesive/bonding agent would provide the quickest return to "useable condition". depending on how/why/where it broke this might last awhile, or it might snap at the first chance. hard to call really.
a new piece would be the best option but might not be available. your best bet would be to contact bose to inquire about it. with it being a bose headphone set the part might be marked up a bit even if they have it. (it is 4 years old after all, they might not carry parts for it anymore).
plastic bonding is best left to people qualified for it unless you are happy with a pile of molten plastic. its not as easy as one would think (i've experimented with it a bit before). normally you end up with a repair job much worse than when you started (too much heat is normally applied).
as for the why...
it could be multiple transitions from hot to cold as ap stated. i've seen this happen a bunch of times. it could also have been a stress crack. hard plastic often will snap instead of bend, and when it goes it is normally multiple pieces. the screw holes are a weak point (and the screws putting forces on the plastic doesnt help matters) so this would explain why it snapped around the point. in any case it sounds like a normal plastic response or due to general wear and tear, use.