AdamR28 Posted February 7, 2011 Report Share Posted February 7, 2011 As you may or may not know, I bust the rear hub on my bike recently so decided to custom make one. It was about 2 years old so had done pretty well! I based it around a 116mm Echo SL Rear Disc hub. The reason for using the 116mm hub is that the disc side bearing is in a much better place (further outboard) than all the other disc hubs available right now. Took the hub apart and cut the hub shell up, then tidied it up. Put some grooves in to help the glue (and sanded off the anodising for a better key). Doodles/calculations... Making the carbon part was fairly tricky but with the right tools not too bad. Started with a copper pipe, polished up: Wrapped it in fibreglass Sliced it off once cured Shiny inside, exactly 22.00mm diameter to match the flanges where it would be pressed onto. Should have sanded it smooth at this point, since the 'lumps' show right through the carbon on the final piece Back on the mandrel, then coated with carbon fibre resin - you let the resin go off a bit so it's tacky and the carbon cloth sticks to it Carbon ready to cure While that was doing, started on the axle Cool swarf, hehe Further along doing the axle 'Roughed' axle - with hindsight I should have done the axle last so I knew all the exact measurements. This would have meant I didn't need to re-clamp it which causes alignment issues and takes extra time and reduces accuracy a bit. Checking to see how the hub would look Carbon cured and ends cut off, testing fit - carbon was a nice press fit onto the flanges, win. Checking fit Turning the carbon down to the right length Rads on the bore to match those on the flanges All the parts on the scales before the axle was finished Drilling the axle out More axle work Finished axle (middle is solid, 7mm diameter so plenty strong enough, cold maybe remove a few more grams here but probably won't bother) Complete hub. 'Official' Echo 135mm Disc rear version is 194g Weight including all the hardware More doodles and calculations... Finished hub! Should be able to get it built up tonight Any questions just ask Ads 1 Quote Link to comment Share on other sites More sharing options...
Rob Leech Posted February 7, 2011 Report Share Posted February 7, 2011 (edited) Mr.Read got skills, that is awesome! Can i ask how you weaved the carbon? like, by hand or mechanically? Use of the auto travel on the lathe? And also how did you heat the mandrell? Or did you bake it afterwards? Cheers, Josh. Edited February 7, 2011 by Rob Leech Quote Link to comment Share on other sites More sharing options...
quick_spider Posted February 7, 2011 Report Share Posted February 7, 2011 You big tart! 1 Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted February 7, 2011 Author Report Share Posted February 7, 2011 Cheers man! Carbon is done by hand (which is why it looks a bit poop - plus I needed the bore to be the smooth bit in this case). I should have sanded the fibreglass down a bit first but that's hindsight... The mandrel doesn't need heating, everything is done cold. With some polish and release agent the fibreglass doesn't stick well and came off pretty easily after it was split with a stanley knife (you can see the cut line in one of the pics). The fibreglass goes off after about 20 mins and the carbon takes around 12 hours (6-8 hours to go 'tacky'). Did all the lathe work manually too, not investigated the auto-travel yet but I'm gonna investigate threads soon so will get onto that Quote Link to comment Share on other sites More sharing options...
Greetings Posted February 7, 2011 Report Share Posted February 7, 2011 I'm amazed that the bond between the flanges and carbon fibre bit are strong enough to cope with the forces in the rear wheel. Laquer the cf Quote Link to comment Share on other sites More sharing options...
Luke Rainbird Posted February 7, 2011 Report Share Posted February 7, 2011 Awesome stuff dude! Quote Link to comment Share on other sites More sharing options...
JD™ Posted February 7, 2011 Report Share Posted February 7, 2011 I'm amazed that the bond between the flanges and carbon fibre bit are strong enough to cope with the forces in the rear wheel. Laquer the cf My first thought when I saw the grooves was that they should have been diagonal or something - I'm no engineer though and trust Adam knows what he's doing. I just figured that you'd want some sort of bond for the rotational forces as well as just holding the flanges in. Looks like a damn fun project though Adam, nicely done. Quote Link to comment Share on other sites More sharing options...
Joe Papasnap Maher Posted February 7, 2011 Report Share Posted February 7, 2011 When can you make me one?? Looks awesome! Quote Link to comment Share on other sites More sharing options...
Rob Leech Posted February 7, 2011 Report Share Posted February 7, 2011 Cheers man! Carbon is done by hand (which is why it looks a bit poop - plus I needed the bore to be the smooth bit in this case). I should have sanded the fibreglass down a bit first but that's hindsight... The mandrel doesn't need heating, everything is done cold. With some polish and release agent the fibreglass doesn't stick well and came off pretty easily after it was split with a stanley knife (you can see the cut line in one of the pics). The fibreglass goes off after about 20 mins and the carbon takes around 12 hours (6-8 hours to go 'tacky'). Did all the lathe work manually too, not investigated the auto-travel yet but I'm gonna investigate threads soon so will get onto that Ritey o, sweet. Ahh, ok, have only seen carbon tubing made a couple of times and they had heated the mandrell after weaving is all. Kewl, got anymore projects to come btw???? Josh. Quote Link to comment Share on other sites More sharing options...
forteh Posted February 7, 2011 Report Share Posted February 7, 2011 (edited) Nice work Im also skeptical as to whether this will hold up, especially with rear disk, Ive a sneaking suspicion that it will shear; that said it will probably last forever. The rim/spokes will give some support to the carbon/flange interface but I think the flex will be enough to crack it over time. Will be interested to see how well it works edit: I miss not having access to a workshop Edited February 7, 2011 by forteh Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted February 7, 2011 Author Report Share Posted February 7, 2011 I have no reason to think it won't work (or I wouldn't have done it, haha) since the glue is pretty strong in shear and I made some axial marks in the hub shell too (but they looked horribly messy so there are no pics of them ). The spokes should take all the force really - the only time the carbon bit will be under torsion is if I'm pedalling and braking at the same time (which is kinda 'incorrect'). The carbon is ~3mm thick so I have no concerns about that breaking! I was tempted not to bother gluing the carbon in fact, but wondered if it would have an effect on the durability of the axle. Rob: Yeah if you make it only of carbon (rather than fibreglass skin underneath) and it's longer than ~100mm I can defo see how heating would be required. A good tip for the future - cheers! More projects... well I just came up with an idea for a front hub but I'll have to think/doodle more on that one... Quote Link to comment Share on other sites More sharing options...
forteh Posted February 7, 2011 Report Share Posted February 7, 2011 I have no reason to think it won't work (or I wouldn't have done it, haha) since the glue is pretty strong in shear and I made some axial marks in the hub shell too (but they looked horribly messy so there are no pics of them ). The spokes should take all the force really? The carbon is ~3mm thick so I have no concerns about that breaking! I was tempted not to bother gluing the carbon in fact, but wondered if it would have some effect on the durability of the axle. I wasnts concerned about the strength of the carbon, more the interface between the flange and the shell, putting axial keys in there should increase strength hugely I could be wrong about the spokes, but surely alot of the spoke stiffness is dependant on the flanges being held straight and true to each other, if you have opposing torsional forces acting direct on either end of the hub (drive and brake) then I can see it failing, I would be much more confident if it werent a disk brake. Well it will either work or it wont, if it fails you will be able to review the design and modify it accordingly. Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted February 7, 2011 Author Report Share Posted February 7, 2011 Agree to disagree I guess The shear strength of the glue should be approx 12 MPa - not really got time to do the maths at the mo but it sounds like a big number haha I've generally found that theory and practice are pretty much unrelated when it comes to trials stuff (apart from very clear-cut situations, of course), but yeah, see how it gets on. Quote Link to comment Share on other sites More sharing options...
forteh Posted February 7, 2011 Report Share Posted February 7, 2011 Agree to disagree I guess I've generally found that theory and practice are pretty much unrelated when it comes to trials stuff (apart from very clear-cut situations, of course), but yeah, see how it gets on. I agree, with the theory and practice, a case in point.... About 15 years ago our R&D manager (an excellent theoretical engineer but not particularly practical with his designs) was asked to design a sewage plant, he used an adhesive to construct a support frame that we would typically bolt/weld together. He specced the adhesive and fitting tolerances correctly, however every single plant using that system failed and cost the company tens of thousands. We now do a mechanically fixed structure and never had one fail. Whilst adhesive technology has obviously improved over the years there are so many factors that can prevent it from performing 100% as the literature states. Call me old fashioned, but I dont have a great deal of trust in adhesives in a structural situation I would like to be proved wrong though! Incidentally, are there any other carbon shelled rear hubs available on the market (not trials specific), I know there are the speedrace topgun ones, have they been proven yet? Quote Link to comment Share on other sites More sharing options...
Rob Leech Posted February 7, 2011 Report Share Posted February 7, 2011 (edited) Agree to disagree I guess The shear strength of the glue should be approx 12 MPa - not really got time to do the maths at the mo but it sounds like a big number haha I've generally found that theory and practice are pretty much unrelated when it comes to trials stuff (apart from very clear-cut situations, of course), but yeah, see how it gets on. Sorry about giving you the old 21 questions, but what adhesive did you use? The highest strength, easily available one that i found for my first frame was Araldite 2021. Spec sheet- http://www.freemansupply.com/datasheets/Araldite/2021.pdf . Josh. Must also agree with your last statement there Edited February 7, 2011 by Rob Leech Quote Link to comment Share on other sites More sharing options...
monkeyseemonkeydo Posted February 7, 2011 Report Share Posted February 7, 2011 Ah, T-Cut. The polish of champions! Nice work Ads, will be interesting to see how long it lasts!! Were you not tempted to just buy some stock CF tubing and hone the ID? Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted February 7, 2011 Author Report Share Posted February 7, 2011 Sorry about giving you the old 21 questions, but what adhesive did you use? The highest strength, easily available one that i found for my first frame was Araldite 2021. Spec sheet- http://www.freemansupply.com/datasheets/Araldite/2021.pdf . Josh. Must also agree with your last statement there No worries - I used what I had lying around, possibly 'Araldite Rapid'... It it comes undone I'll try something more posh, cheers for the heads up! Ah, T-Cut. The polish of champions! Nice work Ads, will be interesting to see how long it lasts!! Were you not tempted to just buy some stock CF tubing and hone the ID? Indeed, I'd never noticed before but it smells and feels remarkably like Brasso I looked at stock tubing but it was only up to around 1.7mm thick and at ~£45 for 0.5m minimum order you can guess the rest of this sentence! Quote Link to comment Share on other sites More sharing options...
totaltrials Posted February 7, 2011 Report Share Posted February 7, 2011 Ah, T-Cut. The polish of champions! Nice work Ads, will be interesting to see how long it lasts!! Were you not tempted to just buy some stock CF tubing and hone the ID? Doubt he has a honing machine knocking around. Looks good though Ads, nice one. Quote Link to comment Share on other sites More sharing options...
monkeyseemonkeydo Posted February 7, 2011 Report Share Posted February 7, 2011 Doubt he has a honing machine knocking around. He has no need- Ads is honed to perfection already. In other news, lathes for internal bore honing glory! And Ads, yeah I can see where you're going with that! Quote Link to comment Share on other sites More sharing options...
Ben John - Hynes Posted February 7, 2011 Report Share Posted February 7, 2011 Wow! That's cool as. Looks a hell of a lot neater than those speedrace(?) ones you stock . Quote Link to comment Share on other sites More sharing options...
Shaun H Posted February 7, 2011 Report Share Posted February 7, 2011 Call me old fashioned, but I dont have a great deal of trust in adhesives in a structural situation I'd stay well away from any modern airliners if I were you then! We use a 3M adhesive called 9323 B/A on our Formula Student program to bond our wishbones, now THAT is an adhesive! Quote Link to comment Share on other sites More sharing options...
forteh Posted February 7, 2011 Report Share Posted February 7, 2011 I'd stay well away from any modern airliners if I were you then! We use a 3M adhesive called 9323 B/A on our Formula Student program to bond our wishbones, now THAT is an adhesive! Ill bear that in mind, but then of course modern airliners arent manufactured in the back of an online bicycle retailers in northwest england Perhaps I should have worded that better, adhesives do have their uses and do work but need to be factored into the design stage and only have limited use in certain applications. Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted February 7, 2011 Author Report Share Posted February 7, 2011 Ill bear that in mind, but then of course modern airliners arent manufactured in the back of an online bicycle retailers in northwest england I won't take offense to that given what a few people who I know who work at British Aerospace have said Quote Link to comment Share on other sites More sharing options...
quick_spider Posted February 7, 2011 Report Share Posted February 7, 2011 Ill bear that in mind, but then of course modern airliners arent manufactured in the back of an online bicycle retailers in northwest england We make parts for aircraft... some parts are very tightly controlled (eg new recent design/manufacturign methods etc) but a lot of the older parts could probably be made better by Adam Quote Link to comment Share on other sites More sharing options...
forteh Posted February 7, 2011 Report Share Posted February 7, 2011 (edited) I won't take offense to that given what a few people who I know who work at British Aerospace have said We make parts for aircraft... some parts are very tightly controlled (eg new recent design/manufacturign methods etc) but a lot of the older parts could probably be made better by Adam Haha edit: of course no offence meant adam by that, a lot of great engineering goes on in sheds Edited February 7, 2011 by forteh Quote Link to comment Share on other sites More sharing options...
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