Making a Carbon Fibre Bike Frame – From CAD Design to Downhill Race


[Music] [Applause] [Music] hi everyone paul here from easy compasses if you regular follower of our channel you'll notice that this video is a bit different it's not our usual structured tutorial this is more of an in-depth case study on the build of this carbon-fibre downhill bike this bike was conceived designed and manufactured from start to finish by the very talented Vlad yard enough I've got here with me he came to us to see whether we were interested in helping him take this design concept through to a finish frame which of course we were this was about two years ago wasn't it yes well write a few things excited us about this project firstly bike frame manufacturer is one of those questions that we get asked very often and it would be a good opportunity to show people just how it's done and secondly it's also fantastic showcase for what can be achieved using the X breakout for two clave prepreg you'll have to bear with us a bit through this video Vlad's a very busy guy and we've been very busy ourselves so we've had to grab shots of this project as it's going through various phases as and when we could so you're gonna see beards and haircut to come and go one or two t-shirts come and go but hopefully by the end of this video you'll take away some new knowledge and a big dose of inspiration as to what can be achieved with the right skill and determination and of course the right materials and support so the finished bikes here yeah over here and it took good few hundred hours to make it and this already have been ridden for quite a while and raced and yeah we're gonna see how a she was made in the video excellent well okay well clearly this is a piece of art as much as a feat of Engineering so we'll go back to the start and see how it was made so the first stage you make your mold is making the pattern that the molds going to be made on in the case of this it's been machined from epoxy model board it's necessary to use epoxy motherboard as opposed to pull urethane because the molds that were going to make made from prepreg and prepreg doesn't work with polyurethane this has been machined on a three axis router that's a machine that's got motion basically in three planks so Danny X Y and then the z-axis not necessarily a five axis machine it's actually most of these areas on the mold can be accessed just simply from a 3-axis point a CNC machine well well first of all go through and rough out the shape and then it will will continue on and do fine finishing passes but if anybody's ever done this before you'll be more than aware of the fact that it doesn't leave you with the finish like this so what did it actually take to go from the machining through to this that we see now with a high-gloss finish well we have to go through you iran's of something and then sealing the bottom the boards and then sanding again up to a final seal and polish as you see we left it all the flanges mm-hmm they only have two coats of sealer and also all the inserts locate they also have only two coats of sealer so this will ensure that inserts and to have some all-day fits right yeah cuz obviously with the sealer as you as you put multiple coats of sealer down onto a pattern it will build up the thickness now the amount of thickness it builds up is although very very small is acceptable on the molded faces but where you need the accuracy where the molds come together the inserts go in that any build up on these areas would lead to inaccuracy on your flash lines so that the tools wouldn't fit together as well but just looking at this I can also see we've got an awful lot of holes put in machined into this so we do have our on 60 pence which is sure that's the to house they've all together right you know its collocation for clumping purposes because carbon walls do not ask tifus talked about a mini oh yeah so that's why we need those clamping points and the closer they are to the edge the Penta okay so these these will have metal pins placed into the pattern so when the molds made and that be laminated around those and we actually end up with holes in the mold itself so all of that aids in just aligning everything perfectly and making sure that the mold is is accurate and true there's a few of a sort of areas of interest that I can see here we've got areas don't look like they're part of the original bike we've got these sections for the inserts how do you determine where you need inserts well everything that's an undercut it requires an insert mm-hmm and also some of the how-to lemonade there is that could come as inserts as well okay so presumably like in this area here one destructor nice that's why we need an innocent but this is all extended mmm-hmm because we need the sensitive to locate into the malt and that bolts in using the same same method and exert that the molds come together okay right so from the pattern and we've gone through we put a sealer down onto it then presumably multiple coats of release agent to ensure we get a good release and likewise on the metal pins they've dropped into these holes they'll need an awful lot of release agent because they've got to be drawn out from a completely parallel ball and then it's on to making the mold itself here's the completed mold that's been taken from the pattern and this been made from an expert tooling prepreg so it's it's done afterwards clave so just on the back human and oven and the black surface finish that you see here actually comes from the prepreg itself it has a glass fiber scrim cloth that supports pigmented resin which gives you really excellent tool surfaces the actual layup of this itself but how many how many late PI's and material do you have in this mold oh it's pretty simple it's one of the surface play and there we have another five working less which oh hey wait yeah that builds up the labels of the envelope and gives this trend to them all okay I'm looking at this it's obviously quite quite a complex shape looking to form and this pattern obviously that's not going to be laid up in just one piece of material is it no it can't be you want pieces with you I started with the corners and all corners they're going cost – 45 so you actually cut the material the surface apply thin strips at 45 degrees so this ensures that all the corners are pushed in same goes for every single pin so we have little strips of 45 are on every single every single pen yeah must have taken quite some time to other person before she covering before finishing the first flight this has all been debugged okay so you see debulk after what between every ply or a deep box on the first by twice when the corners were in and then when the connors were covered so this ensures that the first place stays on that actually just helped to tack it down it helps you back down and the second D locus I left the other night so this makes sure that when I come in the morning it's all my property stuck to the world fully consolidating so the purpose of a debulk are basically pulling a vacuum use it usually with a perforated peel ply you pull a vacuum and it just compresses at each stage of your lamination it takes the bulk out of the material so where the material is normally sort of sagging awaiting the mold by putting it into a vacuum bag it presses it into the corners and really ensures a good layer so once it was all laid up that's been cured so it was done a low temperature initial cure yes a lot of time for change to occur which was slightly longer then it was taken off the tool after good fight with all those pins yes yeah yeah extracting the pins from this once they were if you imagine the the mold the pins coming out of here through this section big there is completely parallel pins actually drawing them out is quite difficult we opted for a trick of using a cordless drill to actually spin them out and that's that reason it did work quite well and so the reason for a low temperature cure why not just take it right up to a 120 degrees and do the cure at that temperature is the epoxy motherboard actually expanding all model boards doom and all materials expand a different race and if we went straight up to 120 degrees this the pattern would actually be larger than it was originally machined so it's cured at low temperature it's then removed from the pattern and then post cured and that does the final hardening of the mold and makes it able to operate it it's its final service temperature just tell them the boss cure we had both halves together bolted up because the flatness of the boards is even after this machined the bottom always have a little bow okay so it's not perfectly stuff perfectly flat so you know in our case the mold was like the edge walked up and the center was a bit lower mm-hmm but this was fixed by bolting them to house together yeah and Oscar in them right so the final stage of the curing is actually done with the with the molds yeah bolted together which will yeah when you do a poster it's slightly softened as the resin and when it it was if they're bolted together they're called flat when it softens the resident then it finally does its final curing hardening it will be much more accurate and by by putting the two together so that's it that's a great tip for anybody making prepregs split tools and yes or no stressing the tools by trying to overcome the the world yeah every time you're cranking them up if you do want more information on how to go from a machine pattern practice and make molds we do actually have videos just specifically covering this topic in quite a lot of detail so if you're interested it might well be worth checking those out we mentioned briefly when we were looking at the pattern that there's a lot of inserts in the frame now these inserts are the sections for like weather where the shock comes through the shock tunnel here and we actually have the frame splitting so we need another piece of the mold that can then be drawn there so I'm looking at these Vlad they're not made from the same material as the mold and they're not made from motherboards so tell me what's what these are all about how you how you made them so basically machine buttons from epoxy okay and then a Custis Innokin over this wall aboard you made a negative from silicon yes from this negative they use high temperature present and graphite it's graphic so the graphite planet okay give it a trend and I've custom the instance into those silicone molds actually just poured the resin into the silicon molds to to actually make that insert forgive me for asking but why not just machining in epoxy insert well again as we mentioned earlier epoxy expands and the temperature and we need something which is with similar expansion rate to do it to because these tools are a carbon fiber and carbon fibers well known having very very low rate of CT so coefficient of thermal expansion pneumatic changes in size with heat and epoxy motherboard although it's quite stable your savings in these cases with it with the large insert like that it was it would actually cause problems through its expansion yeah it might it might cost problems so it's better to have something in the equation right okay so these are graphite filled high-temperature epoxy inserts then yeah which you can see the difference between this one in this one so this one does coke comes out of the mold yeah out of the silicone mold and this one has been sealed polished and released these says they need to be sip on so they come out of the frame easier okay so it when is demos so in terms of the ceiling and finishing just the same as a mold so and exhales s120 board CLS and then easily release agent over the top of it yes okay another reason why we're using silicone molds is in case you break an insert and in your prototype things sometimes you know mistakes happen so this is just making sure that when we more the frame when we get the frame out if Dean so this step we can destroy the in-service save the frame right so they're almost sacrificial yeah the sacrificial yeah then we can just go and custom elias if so and that's it okay well right need easy way to keep making the insert section so we've got those one had to bear they're leaving molding space for the bearing journals bottom brackets lower linkage math there we go fantastic okay well i suppose what we need to go onto now this is the really interesting bit and see what goes into a lay up on the bike so here we've got the prepreg materials that are getting to be used for the actual frame construction itself we've got the x-ray XC 110 system here which is now an autoclave so just in the vacuum and in an oven and we've got a woven fabric 210 gram and then a 300 grand directional the individual pieces of material are cut sized by hand and mark to make identifying the correct piece easier during layup in volume production this process would normally be performed by a CNC cutting machine the majority of the unidirectional fabrics now been cotton we've seen that that's been done oversize to allow a little bit of adjustment and alignment and and actually tailoring it on the job but this template thing that you're doing here with the masking tape why are you doing this at this stage well this is specifically for the first layer which is not 2ds gonna be twill okay and we go for the raw cover finish so all the weed needs to be adjusted so the frame is made in five or six separate pieces and those pieces they need to mush together right so this is this is templating for the woven layer the twill layer that's going on first and you're using these templates to make sure that the the weave is going to align accurately and a lot of that will be presumably for cosmetic purposes to make it make sure that the clothes yeah because the frame is going to be left in that sort of natural raw carbon finish so this is the complete kit of parts then how many how many parts are there in this frame Bow Wow so 300 individual pieces right I suppose now we've got the kit of components it's time to see the layup itself so these molds are all prepared with release agent and ready to laminate onto so what's the first step word or the first step is the head piece so this is working with the 200 gram woven fiber first and just systematically lay that down onto the moulds and you're doing both of these simultaneously do part of this also clipping the it's mirrored yeah I suppose it helps it makes things a lot quicker if you're working on both molds at the same time and just do the same component on each one and then move UA between laughs okay all right let's see it done the first ply into the mold is layer that will be visible on the outside of the part so when you are looking for a really good cosmetic finish extra care should be taken with this ply to ensure that all of the weave is perfectly oriented laminated and aligned one side of the frame is trimmed down to the mold flange and the other will be left protruding to start the laps that join the frame halves so now you've got the first pie fully laminated you're choosing to do a debulk at this stage is that right yes it always helps after the first layer so with complicated pass like this it just pushes all the corners down and gets the detail right so just yeah consolidating it into all these sharp features and details in the frame now that we've got the first Pilate up and DeBolt what's the next stage well it's the second play which is again we use different diagram well but it's gonna sit at 45 plus minus 45 degrees essentially just the same as this first layer but we're using the same material but turn around through 45 degrees presumably just to give it more even strength throughout yeah it's just strength of the skin the second ply is laminated in just the same way as the first the 45 degree orientation increases the torsional stiffness of the tube prior to the unidirectional plies that will follow so we've got the first two plies into the mold so we have the 0 90 waving fabric and then the plus minus 45 degree woven fabric after that so the next layers to go in or unidirectional carbon now unidirectional carbon has all of the fibers running in one direction which means all of the strength or nearly all of the strength is running in that direction so in the case of a bike frame how do you take most advantage of unidirectional fibers so the basic style we run along the tubes so this way we tie head tube to bottom bracket to all the month points like where the linkages go and where the show go about the use of the UD is actually around those same points to reinforce and to have extra strength the case of a tube you want the strength down the length of the tube so we predominantly align it the fibers down that way and then maybe on mounting lugs you would where the loads are going in a different direction you wrap it around to put the load through in whatever direction it is traveling in let's start laminating as this frame already has good torsional strength and hoop strength provided by the woven surface plies the unidirectional material is oriented straight down the length of the tubes in the case of this build the main tubes consists of two plies of 210 grams to 212 on the surface followed by four plies of 300 gram unidirectional and finally back to the further one ply of 210 gram to 212 this laminar is over specified for the build and will almost certainly be reduced by two or three plies after this first proof of concept has been tested stressed areas such as the head tube suspension man-things and bottom bracket will have more plies that stagger into the main tubes forming a taper to spread the stress concentration so with the layup almost complete this is a great opportunity to go around having a look at how Vlad's tackled some of the more complicated or challenging areas of the frame so the first and most obvious thing are the lamps we can see here these are not just a straight lap there are actually staggered and could you explain why why you've done it this way and why it's the best way for for a bike frame well this way we by having all dealers exposed at will we make sure that everything is connected from this half to the other half okay and on the plus side we have the audio D let's say for example between first and second level of the twirl that you see mm-hmm you have UD encapsulated in right so what looks like just twill at this point is actually a has actually got UD buried inside there as well yeah further down below the edge and so on the counterpart from this staggered lap we've got the same thing staggering in in in Reverse here and so I suppose the theory is that these these laps and the staggered sections here yeah they're much the other half match the other ha and this way we have a much more constant thick thickness in the laminate yeah so keeping a unit relatively uniform wall thickness throughout the tube okay so other areas I mean certainly let's take a look around like the shock mount here this this is another area of the frame it's not just a straight tube it's highly stressed and could you go through the process of achieving a good result in components and areas of the frame like this so basically we can see only the top layer here but in the needed top layer we have any directional carbon going around the pen the reason why laminate around the pin is because for example if you drilled a hole there we have fibers which are just been broken effectively by drill bit so now all the fibers they do what they're supposed to do this area is completely solid with carbon so there's not gonna be any vacuum bag in there presumably it's really critical the number of layers that you put in that area so looking at the head tube I can see we've got inserts in a very similar way than we had around this shock mount here but it does look a little bit more complicated so could you run through what the what the layup is around here and what the main considerations are so basically again under the twill we have lots of ug wrapped around the bearing cups okay so yeah uni-directional spiraled round there because effectively that's where you steer a tube goes through your bearings are sat into the frame there and this is under huge amount of strain coming up through from the forks so that hoop strength that you get from UD is absolutely key in that area and and then we've got the laps at the front here just like we have right we do have the labs which lock the stopping the bottom of the head cube and the front of the head tube but again we have the UD here also connects to because we don't have any laps here yeah the function of those two hoops there to keep the two halves together in this area exactly so so this area here actually becomes almost like a bonding face that mates to the other side and because the vacuum bag can't get in to that corner there again this must be very critical on on laminate thickness to make sure you get good consolidation between the ten it's real nice like on the in the shock mount it relies entirely on the how much carbon listen right so purely on the compression provided by the bada tooling okay next section we're going to look at here is is this part of the frame here now this is actually the shock tunnel so it's where the frame wraps around the rear shock unit this isn't a straight forward compression fitting like that it does does have a vacuum bag as well so could you explain how this one works well we have a combination of bug and compression area okay so towards the rear here it's very much the same as yes so where the drop-off or the linkage is marked it yeah the insert actually presses down that that provides a consolidation just the same as here and then this section here presumably these now we'll need laminating yeah they do need laminating with the reason why they're not laminated because I had to check again like few times if the compression wall there is all right and if the lapse like she opened correctly and we don't want them overlapping on each other so where the linkage mount is there that's a solid laminate in there very much the same as around the actual shock mount here and then this section here will have a vacuum bag pass through it yeah okay so presumably now the next stage is to just laminate the material onto the inside of these to effectively close that and turn it into a short squat tube we now have all of the carbon fiber laid up into the frame so we're going to be moving on to the vacuum bagging stage now it's a lot more common you'll see in mass production to use an inflatable bladder which is done in billet aluminium tools close together and pressurized however for prototyping and small volume production is perfectly viable to use a vacuum bagging technique now it's a bit strange to think that a vacuum can be used to apply pressure onto the inside of a tube but hopefully this will show you how it's done so what's the first stage in this process what basically is cutting the box to size okay so the vacuum bagging tube cutting that and then seemingly sealing the ends okay let's get going so now with vacuum bags made in sealed they're ready to go into the mold but before that I understand you're going to put some release film down and that's there to stop the bag from gripping onto the surface yeah we do force or release film now just on the half where the laps are it's basically will allow the bug to slide in position itself into the malt so when we apply the vacuum with the prepreg being quite tacky on the surface you've got the vacuum bag if you you imagine having a bit of pressure against that it's it's very difficult for it to slide and move out into the into the frame so if we use some release film that then lets the bag sit in and slide around the real thing to be careful of here is that you don't get any release film going onto the wrong side of your lap if you get a bit of a release film between the lap and the other side of the frame you're going to have no bond strength whatsoever and that could be a potentially get very dangerous situation to be in so the release film is just going into this one side on the side of the laps and then there's no risk of it subsequently getting into the gap so the first bag is going to be the one through the on one side of the shot tunnel here yeah that's correct and then we're closing soon so it's very important to make sure that all of these laps don't get trapped underneath underneath the edges there this is the four bags in the mold so each one of these is sealed at the end so it's not a continuous tube so we've got one bag that comes in through the head tube along the top tube and meets here at the seat tube let me see that pairs against the bag that's here we've got this seat tube bag on this component and on the other side so we've got two bags going in through that same aperture in the seat tube and then they pair off either side of the shop tunnel and again they're sealed off at the end here and meet the fourth bag which is this one on the down tube which comes out of the bottom of the steerer tube so I've known singing here you've got an awful lot of creases and wrinkles in the bag and why is it important to have this much extra the profile the tubes it tapers out so even though the bag is do the empty of the bag is enough to cover is good to develop areas like this it's same for the bottom bracket it's you can do it this way I can good you can go like this way it's as long as you have full coverage of the area yeah yeah and as long as there's enough back to push the laps out that's job done and so why is this not just done with one sort of continuous bag why have you got four individual ones or it could be done with one buck but then if you want to remove the bag in which case we'll in this case we want to remove the bags it just makes it easy to pull them out separately so this way they won't be lock in any way after curing yeah you're just pulling out one continuous bag rather than a hoop that would be you'd have to tear yeah also the that's one of the reasons why we put also the surface filler yeah okay so the next stage now is to is to close this up this is pretty high stakes so zoom ibly it's just like we did with the shock shock tunnel inserts making sure everything's folded in neatly that you get no material trapped on these barriers we've got the molds just held slightly open obviously we tried to get all of those laps to fold in as best as we could but actually to make to make absolutely certain that the dam we can gradually close the mold and go in through the gap and just push the laps in to make sure that you never get pinched between the two clamping phases for these bolts that are clamping the molds together notice that this is a six millimeter bolt it's actually going through an 8 millimeter hole that won't help any when in the alignment so what are you using to make sure that these moulds are sitting perfectly and accurately aligned so the first thing that actually relies the front of the mold it's the inserts yeah yeah but because we don't have a nice it's aligning them all to the back we have few few of those pins we just use the most location please so we just get a 8 mil pin and it just goes in so this mixture is located yeah ok couple more on the buck and the rest is just and so all of the bolts are just at it to clamp the mold faces so these four inner bags are now projecting out of the clamp top mold and this whole assembly now goes inside another vacuum bag that will surround it and the inner bags will come through the outside of back hopefully this will make a bit more sense when you actually see it so essentially all we're trying to do with the inner bag is breach the seal of the outer bag so we've got the seal to the outer bag the pink bag here so we draw the seal back tack the inner bag across the sealant tape then seal over the top of that bag with another section of tape which then allows the outer bag to fully seal around it so now in this section here we actually have a breach through the seal meaning that the ambient atmospheric pressure when we draw a vacuum on the main bag the atmospheric pressure is not sealed to this inner bag and so that will inflate the atmospheric pressure so it's all bagged up now so this is basically ready for a cure but before that we're going to do a bit of a debulk how long are you going to leave this under vacuum oh we're going to leave this overnight and put in your debulk overnight that gives us opportunity to make sure that the bags holding a perfect seal and gives extra time for the laminate to fully consolidate so let this under vacuum debulking overnight and so now all that's left is the final cure for this cure we're using the X preg XC 110 extended cure cycle which is a two-step cure cycle with a final cure temperature of 120 degrees see full details of the recommended cure cycles can be found on the x Prag XC 110 technical and processing data sheets on the easy consulates website so this is the frame exactly as it comes out of the mold so it'll be a great chance for us to take a look see how the inserts work and see the standard of finish that's been achieved first thing black we've got these these inserts and they make a lot more sense now I can see them integrated into the frame so removal process for those what what's involved oh it's pretty simple they just lock in the amount of place okay with the draft angles positioned correctly we should be able to do this with no much trouble yeah yep that was a lot easier than I would have anticipated and then yeah let's get those out so all the inserts are out that is essentially the the final frame prior to finishing so looking at this you can see we've got quite a bit of flash there's the occasional bit where the odd fiber has come out into the flash line that's what you're trying to avoid when you closed the mold but as long as you only get very slight pitch no single fibers they will get clamped into the mold and won't cause a problem so if we get up really closely to this top tube section here you can see the the end result that we've managed to achieve straight from the mold now there are some very very small surface pinholes here this would be typical on a part like this that's got multiple plies the vacuum bagging is inaccessible during the processing but these are very insignificant they don't really have any structural bearing on the part and as soon as this is have the paint or the clear coat these are become completely invisible so it's just a good opportunity to show you the great results that you do get straight from the mold with the XC 110 system so with the front triangle molding complete what's next from here well repeat the exactly same process for the rear triangle so this is the rear triangle sections all laid up and ready to vacuum bag on the face of it here it looks very similar to the front triangle and is there anything in particular that's different about this well you're right it's more as the same the difference comes in the structure most of the UD is on the outside right of the tubes and these say we have less material because we have those laps' closing on so the this section that will close to this is laminated thinner and then these laps here will will give that area more bulk yeah oh the laminate is gonna be even inside out so this way okay well let's press on and do the vacuum bagging same as the front triangle and these are going to go into an envelope bag and these internal bags are going to come through the seal on the outer bag putting the vacuum on to the inside of the tube so this would be cured on the same cure cycle as the front triangle so we're going to pop that in now and we'll see in a few hours time for the D molding so the two sections of the rear triangle out of the mold what's the next stage from here Vlad well same as the frontal angle we need to give them a good clean in deburr don't eat a problem for bonding with the rear triangle now D bird and trimmed and prepped ready for bonding it's now just a case of aligning those two parts together so I see here you've got the two sides of the frame so you got the the front triangle and the linkages and why are we using this rather than a full-blown jig well we're using this because it's a first prototype and because everything is modeled on the front triangle it gives us pretty good alignment for the rear okay so it's just a case of presumably taking those two elements using a structural adhesive in between the two and then aligning it all up yeah right to prepare these parts for bonding the mating faces were degreased and are braided with 80 grit sandpaper there is approximately an or point five millimeter gap which allows for an effective bond line and will allow a small degree of adjustment and for final alignment the adhesive we're using here is the Voodoo glue vm 100 methyl methacrylate adhesive which is an excellent choice in most composite bonding applications we have plans to do a video dedicated to comparing and testing adhesives if you want to hear about this when it's released please subscribe to our channel and hit the notification bell with the front and rear triangle now essentially complete or at least all the composite side of things are what's the next stage from here to take this to the to the finished article well next stage is a little bit more sanding so I'm go with a setting clear coat and I'm going to keep the roll look of the carbon frame right so you keeping the raw carbon finish with a satin clear coat right well next stop spray booth so this is it these are the completed frame components back from paint so from a composites perspective all the works now done what are the next steps for this well we need to assemble it so put the linkages in put the shock and then put the rest of the components and yeah the plan is that this is going to be race this weekend right so it's getting straight out this weekend and see how it does we're only going to have like one day of testing before the race and that's it right okay well if you're racing it this weekend I think we should get the GoPro out and hopefully all goes to plan the next shot you'll see of this bike on the track I hope you've enjoyed following us along through this project to support our channel we always appreciate a like and subscribe if you're feeling inspired and want to learn more about composites please check out our other videos where you'll find more detailed explanations of the various processes and techniques that you've seen used here and of course you can find more information on the materials and equipment used in this project on the ez composites website [Music]

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