Bugger. Second set of 4 x10mmx500mm linear shafts turned up from China today, these ones just a bent as the first set they sent me :(. They are all about 1/4mm off axis at the 250mm mark - looks like they have a bad batch :. Yet more from a different batch now on a fast courier
On the up side, I now have 8 very slightly bent 10mm shafts which will be fine for something I guess. Any suggestions?
Incidentally, this is an isolated incident; all the other linear motion stuff I’ve bought from China in the past has been fine.
Sounds to me they are doing their normal. Bend over backwards to get a deal then don’t do inspection on materials once you sign up with them.
No, that is not their usual. As I said above, everything else I’ve bought of aliexpress, maybe 20-30 orders has been fine. I can’t fault their customer service, they always get back to me within an hour and just send replacements without any argument.
@Gareth_Owen Maybe, I’m not au fait with the methods for straightening linear shaft. They are crazy hard so I suspect they won’t respond to being rolled or whatever.
@Tim_Rastall still no inspection has been do. I used to work in engineering and always check stuff like that as it was automotive based. Surely there’s a local firm that can price match.
I would go for straightening them using a press. Bent anyways might as well try and get them straight.
@Wayne_Friedt if they are hardened and ground you cannot straighten them unless you soften them.
@Nigel_Dickinson Well that makes things more difficult. Thank’s for the info.
What happens if trying to straight one, end’s up breaking?
@Wayne_Friedt it acts like a spring and goes back to its original position or breaks depending on the way its hardened.
@Nigel_Dickinson Gotcha Thanks
softening them is kinda easy though. its called annealing. get a magnet, a torch and a bucket of sand. Get the bar red to orange hot with the torch, until it stops being magnetic. then let it cool enough to become magnetic again, then heat it up till its not magnetic again. you can redo this process a few times, you ideally want to get as close to but over the transition temp as possible, then plunge it in the sand and let it stay there to cool for a few hours. the slower it cools, the better. fin!
hardening is pretty similar, but you want to cool it as fast as possible.
my point being that you can probably anneal, straighten, then harden the rods yourself. they probably wont be as good as ones done professionally, but they’ll be OK.
@Richard_Betel the rods would need regrind and I think you would be hard pressed to get the tolerances right, that’s why you harden then grind the rods. I suspect the rods that @Tim_Rastall received were done the other way round.
I’d order from some place domestic. If they are plain linear shafts, they won’t be too pricey.
~ $60 for 4 10mmx500mm shafts
@Daniel_Joyce great if you live in the US but I’m in NZ. McMaster-Carr don’t ship overseas (I’ve checked)… I’ve no doubt ill end up with straight ones eventually. They cost $30 inluding shipping from china btw.