ZeroMatt Posted March 12, 2012 Report Share Posted March 12, 2012 Surely it's just the atmospheric pressure, so ~10200 kg/m2. Quote Link to comment Share on other sites More sharing options...
monkeyseemonkeydo Posted March 12, 2012 Report Share Posted March 12, 2012 i just know that it makes a vacum. I don't think you do. Quote Link to comment Share on other sites More sharing options...
Rob Leech Posted March 12, 2012 Report Share Posted March 12, 2012 I think this is silly. Carbon is no doubt stronger than alu or steel on paper and in tests like that, the problem lies elsewhere. If I had a bad crash on a steel frame, as long as it did not crack i would still ride it. If I had the same crash on a carbon frame I would be very worried as most damage would not be visible. Also a bad scrape can ruin carbon where steel or alu would be fine. Carbon is amazingly light and strong but I think it is better off kept to uses where it will not constantly be smashed into stuff. Cant be bothered to type this out again, so i copied it from the tryall carbon fokrs thread, i apologise if there are any unrelated bits - Carbon is a lot less susceptible to chips and scratches than people think, yes, i'd agree that large gouges would create an area where certain stresses would cause a fracture, but if koxx have done the lay up right, it shouldn't be a problem. Looking at a cross section of a fork lay up, the main structure is actually visible as a thick, single wall, showing that the varied layers of fabric have almost been fused by the resin (not too sure what the appropriate wording is for that), so a minor chip or scratch, in most cases, would be very much superficial to the forks structural integrity (obviously more factors would come into play, like position, depth and probably angle in this case). They are also extremely repairable, as long as you get to them in time, simply a bit of wet and dry and some super glue will sort any small chip (an epoxy resin (araldite or similar) would be a better option if it's not a quick fix whilst out nd about), which is something people dont think about when looking at carbon, it is only held together by a resin at the end of the day (also a bit more complicated than that, but you get the jist ) and will more than likely of had an epoxy gel coat applied to obtain the polished finish, which will be very susceptible to chipping and scratching, but is not a factor in the structure of the fork. "i am just saying i dont belive air pressure can be stronger than pysical pressure coming from an set of 4 pistons acting on a smaller area than a pump acting on a large chamber." Forgot to multi quote, you'd be very right in saying this, as most manufacturers producing carbon components often prefer a press to a vacuum system, but most of the time either size or shape of the component would stop them from doing this. I can pretty much gaurantee that the larger majority of carbon bike frames will be made this way, using a mould (normally ally) and bladder technique where the mold is in two halves, the carbon is layed up in both halves with a latex ballon (bladder) being used to compress the carbon into the mold. This will then be put into a press, which also creates heat (not sure how, wether it is simply the pressure or if the upper and lower plates are charged), curing the part (if pre-preg is used, which in the bike trade, is quite essential for the structural needs of a frame enduring quite a few different forces). You only have to look at how many manufacurers now make a full monocoque, not many, as they have been found to be weaker than a "3 piece" monocoque due to the processes in the manufacture. Why struggle to create a single, flawless piece when you could quite easily make 3 smaller pieces where problems are less likely and can be found before either production or moving to retail? I hope thats sorted some peoples questions/quibles on the subject . Once again, sorry for the rabble . Josh. Quote Link to comment Share on other sites More sharing options...
dezmtber Posted March 12, 2012 Report Share Posted March 12, 2012 good answer. i will say i like this tread so far i am learning something out of it at least. a good way of repairing carbon also is to mix the dust from cutting and filing carbon to resin and using it as a filler onto cracks and chips. just like cement. Quote Link to comment Share on other sites More sharing options...
monkeyseemonkeydo Posted March 12, 2012 Report Share Posted March 12, 2012 a good way of repairing carbon also is to mix the dust from cutting and filing carbon to resin and using it as a filler onto cracks and chips. just like cement. That will only be a primarily aesthetic repair though surely. The carbon dust will not be a good replacement for the severed fibres and associated reduction in strength. Quote Link to comment Share on other sites More sharing options...
dezmtber Posted March 12, 2012 Report Share Posted March 12, 2012 small cracks and chips. not full failures of the weave. complete failure of the weave will need at least wraping of some sort even then i would not recomend trying to fix or repair carbon that has snapped. Quote Link to comment Share on other sites More sharing options...
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