I tested it first and it the noise was normal.But during i was arranging
things,the inner metal core,accidentally,slipped on the floor(not sand or something).It was covered with very light dust/tinydebris(hardlyvisible),
so i cleaned it carefully,in order not to remove lube,until there wasn’t any visible dirt.But after i inserted the core back to the sleeve,the flex-shaft started to make a noise.(See attached
video:
.What can it be,while 2 seconds before it was fine.Thanks.
Welcome to the forum, xchcui! From your description, the first thought was a grain of sand or something like that. But since you cleaned it so well, is it possible that in the drop, something was bent?
The core lube,probably,with dry lube(maybe graphite powder,as you mentioned)as the core was dry to touch and my fingers turn black.But i cleaned only the tiny debris/dust(there wasn’t any graphite residues)that stuck to it from the floor.
Is the grinding noise,in the video, produced due to bent metal core?Can i fix that?
The noise is heard the most near the end of the shaft(where you hold it)and there is a bearing inside.I though that it is bad bearing,but i don’t see any reason that it will fail after 2 minutes.Do you recognized this grinding noise?
As I don’t have one of these shafts I’m probably not the best person to offer advise. That said, can you see the bearing? Could you get the tip of a needle nozzle of a LaBelle oil tube to it? Just a drop or two might help. No harm in trying.
The point is,that the bearing was okay it wasn’t harmed.I was hoping that someone could recognized the sound in the video and will know what is exactly ithe source.Anyway,thanks for your responds.
That’s likely a bearing noise – you may have damaged balls or bent or misaligned the outer race.
You might be able to add a drop of appropriate lubricant to the side of the bearing (I’d use a PTFE- or graphite-loaded light oil). It might be possible that you’re running the shaft at higher speed to cause vibrations to build up in the bearing, and if it’s just that the bearing is running dry that might cure it.
You might also have introduced a kink in the shaft or a dent in the handpiece shell that is causing misalignment. I am not sure there is a reasonable-cost way to solve that if it is the cause.
It sounds like it is the bearing noise,but i can’t figure how.I mean:when i first test it(new),i only tested it for ~5 minutes and there wasn’t this noise,after that the metal core slipped…and the noise appeared.If the bearing was dry or bad,it should make this noise in the first test,shouldn’t it?There is a chance(big chance)that during the first test,i bent the flex-shaft too much,(while the tool was working),but not a sharp bend,U shape bend and for a very short time.Can this damage the bearing so fast?The issue with this flex-shaft is that it is sealed,you can’t dismantle the hand piece and look inside like you do with dremel brand.
Bending or kinking the shaft can certainly cause noise, but it would be in the shaft at the point of contact between the kink and the jacket, not where the bearings are in the handpiece. It seems unlikely to me that normal bending of the shaft (or accidental impact if you happened to drop it ‘just in the wrong place’ between handpiece and shaft) would ‘cock’ the bearing in the handpiece or loosen its fit. What I think I hear are dry balls with misaligned inner and outer races or the wrong clearance.
I thought you said in an earlier post that you had extracted the inner shaft and bearing and wiped the outside of the bearing clean.
I don’t know if returning the shaft for exchange is practical or cost-effective. I have done noisy “sealed” speedometer-drive cables by soaking them in a mixture of kerosene and engine oil and periodically rotating the inner shaft with a drill; I would expect that to (at least temporarily) quiet small bearing noise. I am sure there are better combinations of lubricant and solvent for a Foredom-type shaft, and hopefully the experts here will advise.
I cleaned only the metal core and i haven’t deal with the bearing yet,but i assume that you are right and this noise comes from the bearing.I just was surprised that the bearing didn’t make this noise before i dropped the metal-core(5 minutes after first use).Thanks alot for your help.
