How to Cut Carbon Fibre Sheet and Carbon Fiber Parts (Technique & Safety)

welcome to this easy competence guide to cutting shaping and finishing carbon fiber sheet and carbon fiber parts the idea of this tutorial is to cover some important safety information and also explain the best techniques for cutting this material and then shaping and finishing the cut edges this guide should provide useful information to anyone who needs to cut and finish carbon fiber parts whether they are untrimmed original parts like this stock carbon fiber sheet material like this that you’re going to cut to make profile parts or like this could be a seat post or handlebars that you just need to cut in order to adjust it this tutorial is made up of the following sections firstly an explanation as to what carbon fiber parts are made from some important safety information when cutting carbon fiber tools and techniques for cutting and then the best tools and techniques for finishing cut edges and then finally we’ll look at protection for cut edges if you’re unfamiliar with carbon fiber it’s useful to understand what this material is before you start working with it carbon fiber parts are actually carbon fiber reinforced plastic which is to say that there are a composite material made from a plastic Aryeh cured resin which starts off life like this and then carbon fiber reinforcement which looks like this it’s important to understand this because both the resin and the carbon fibers create their own risks and also considerations when working with the cured composite when cutting or shaping carbon fiber parts it’s important to follow some good safety practices if you do so then cutting this material can be made perfectly safe rate of evidence to date from studies specifically into the dangers of working with carbon fiber overwhelmingly suggests that it presents similar risks and so she’ll be protected against in a similar way to working with other dense materials like hardwood or fiberglass in addition some resin systems may produce toxic smoke when caught using high speed machines the main risks are irritation to your skin eyes and lungs caused by the fine dust particles and also danger from splinters and sharp edges of the cut laminate if you’re using high speed cutting tools then obviously those are the risks associated with there machines one final risk comes from the fact that carbon fiber dust is electrically conductive although in practice this is more of a danger to your equipment rather than yourself all risks and irritation from working with carbon fiber can be significantly reduced by working in a well-ventilated environment and ideally with some localized extraction in a workshop environment that might mean working with a position black extraction arm like this or even working on a downdraft table like this now these will draw dust down into the filter before it even gets a chance to become airborne but if you’re working at home or you’re doing more infrequent jobs then something as simple as a vacuum cleaner like this positioned on the table is near to where you’re working as possible we’ll do the same thing and suck up dust as it’s being created carbon fiber dust itself is not toxic however five particles of it can irritate your lungs in the same way that cutting materials like hardwood can the plastic element of carbon fiber parts is most commonly a thermoset resin such as epoxy polyester or vinyl ester and of these epoxy resin specifically can produce toxic dust when cut using high speed equipment because it’s often so difficult to know which resin system has been used in the manufacture of a part we would always suggest assuming that high speed cutting could create hazardous or toxic dust and so take appropriate precautions to safeguard against both risks as well as extraction or good ventilation we always suggest wearing a respirator when cutting carbon fiber so let’s take a look at the different types of respirator that are available we suggest avoiding disposable nuisance masks like this they don’t really have any sort of guaranteed protection factor at all and don’t offer a good level of fit either instead for occasional use a p1 mask like this is a good starting point for improved protection a p2 dust mask like this filters out finer dust particles and evolved example like this one is much more comfortable to wear for longer periods of time for prolonged or regular use you might want to look into a reusable respirator like this one these tend to offer much better fit ensuring that dust can’t find it way around the mask again look for a p2 stamp or even a p3 rating which safeguards against high toxicity materials the next safety consideration of your skin the two risks to your skin when trimming carbon fiber parts the first being cuts from the sharp edges and the second from irritation caused by the fine dust if you’re cutting down ready-made carbon fiber parts like this which could be a seat post for example then you’re very unlikely to encounter any sharp or dangerous edges but if you’re trimming freshly d molded carbon

fiber parts like this then exercise great caution because the edges of the laminate where it’s been where it goes thin can be absolutely razor sharp and give you a nasty cut skin irritation from fine dust particles is very common when cutting or sanding carbon fiber this irritation is most likely to affect your hands particularly in between your fingers and also your forearms thin surgical gloves like these can be worn to keep the dust off your skin but for heavier trimming operations we would always generally opt for a disposable full suit as well if you do get carbon fiber dust on your skin then wash it off with cold water and not warm water or hot water this will avoid opening your pores and making the irritation worse last piece of safety equipment we would recommend is eye protection if you’re only fettling or making small adjustments to a carbon fiber part by hand then there’s very little risk to your eyes but for heavier cutting or power tool use than safety glasses like these offer a good basic level of protection or alternatively for heavier trimming operations than a set of goggles like this is recommended there’s nothing particularly difficult or unique about cutting carbon fiber many people assume that it cannot be done without expensive or specialist tools but this is not the case better more appropriate tools will make things quicker and easier but if you’re careful and you go about it the right way you can certainly cut carbon fiber with fairly standard tools as a general rule when cutting carbon fiber you want the cutting surface of the tool that you’re using to be as fine as possible a finer cutting surface will splinter and fracture the laminate much less than a coarser cutting surface this means that the best way to use don’t in fact have teeth at all instead they have a fine grit on there cutting edge like this perma-grit hacksaw blade or like they’re slitting discs which is made of a ceramic material which always gives it an abrasive surface at its cutting edge if you don’t have a cutting tool with an abrasive edge then you can still use toothed blades but you’ll find that there may chip and splinter the laminate more when cutting if you do use a blade with teeth then you want the teeth to be as fine as possible this means using blades designed for metal rather than those designed for wood in tools like axles and jigsaw blades in all cases when you cut carbon fiber you should always cut wide of the mark compared to exactly where the finish line should be you’ll cut a bit past that so that you can rub it back using a sanding block or abrasive paper in doing so if there’s been any chipping or splintering of the laminate during the cutting process and this can be rubbed away leaving a smooth and accurate edge which will demonstrate after so let’s now take a look at how range of different tools cut a range of different types of carbon fiber material so we’ve got a good spread of different types of material including an easy to cut foam core panel some solid prepreg carbon fiber sheet a laminated part a poltroon and the seat post to cut down and then a range of tools some of them are more appropriate for cutting different types of material than others but we’ll work our way through and demonstrate which ones are better and what sort of cut you can expect so because we’re onto the actual cutting of the carbon fiber now we need to pay attention to our safety gear so we’ve got respirator and goggles and then we’re just going to use a cutting surface so that we can hold the materials and be able to soar off the edge into space over this downdraft table so we use a piece of foam for that here’s the various bits and pieces that we’re going to be doing the cutting demonstration on just put the seat post in the part to one side and concentrate first of all on these two sheets so start by just marking out a simple shape of course this is only for demonstration purposes so we’re not paying any particular attention to the measurements or the shape or or accurately marking these out first of all we’ve got the prepreg sheet this is pure carbon fiber two millimeters thick and we’re going to be cutting it first of all using a hacksaw so a normal hacksaw with a metal cutting blade in just starting off gently along the cut metal cutting blade actually does a really nice job on a prepreg sheet like this it wouldn’t be as good if we’d got corners to get round or a tight shape to follow particularly but for straight lines like this and you can see the metal cutting blade making very light work and a nice smooth cut on this prepreg sheet so looking at the cut edge on this one now you can clearly see that’s done quite a nice job as really very little finishing we’ve got a little bit wide of the mark like we said we would and we can rub that back later using a block moving on now to the next tool we’re using a dremel now this is a 40 flex Dremel so it has the motor remoted and then a flexible shaft making it very easy and lightweight to handle and we’ve got a perma-grit tungsten carbide abrasive wheel in the in the dremel now this is probably the most professional way to trim carbon fiber parts so if you’re doing it regularly on our manufacturing side this is the way that we would be

trimming all manner of complicated shapes and as you can see the perma-grit wheel makes extremely light work of this rigid prepreg sheet and we’ve just got wide of the mark again so that we can tidy up these edges afterwards to be honest you can probably go closer than that with the Dremel and a good level of accuracy so sticking with the Solid 2 mill prepreg sheet we’re going to demonstrate a way that you can use a hand tool to take out this middle detail instead of the Dremel that we’ve just shown you so first of all we need to drill a hole through the sheet so that we can get the rod sawed into that Center detail section using a perfectly normal rechargeable drill here and the drill bit again is perfectly normal metalworking drill bit now we’re going to leave this show you all the way through the drilling process it does take a bit of time but this does demonstrate that a normal drill bit will will drill through prepreg sheet like this and without too much difficulty we probably choose to use a pedestal drill make slightly lighter work of this but normal hand tools like this will do the job and that’s just going to leave us with a slight amount of burrowing around the hole take a look at the other side as well again just a bit of burrowing so if we were trying to drill really neat holes rather than just opening up a hole for the tool then we’d file that back to tidy up the edges so opening up the rod so now so that we can thread it through the hole that we just created and allow us to cut out this center section and then just latch that back into this now these perma-grit rods or files fantastic for quite detailed shapes getting inside have cuts like this I do make reasonably slow progress you’ve got quite a few mill of cut and that obviously slows things down but you will get there in the end so they are a useful tool to have in your collection for detailed like this if you’re cutting switches out of a panel they can obviously get in and tidy up all these edges now the nature of the rod saw means that we’ve got slightly wobbly edge particularly ones a little bit smoother than the other depending on how difficult it was to get a position on the sheet while we were cutting it this edge has got better wobble on but we’re going to take that off later using a file and smooth up that edge so in marked contrast now to the hand cutting that we’ve just been doing with the rod saw we’ll get on a good quality mask and safety goggles for this one because we’re demonstrating using an angle grinder with a slitting disc in to cut this solid to mil free thread carbon fiber sheet now an angle grinder like this will make extremely light work of even the thickest solid carbon fiber laminate really needs to be straight lines you’re cutting it’s not much useful detailed or curved surfaces so trimming complicated parties output for straight cuts like this this really is a fantastic tool need to exercise care because it’s it’s a powerful tool but it does cook very quickly and leaves you with a very smooth edge with no bearing at all so for our next demonstration we’re going to be using foam core carbon fiber panel now this is a single layer of carbon fiber either side of a structural hotel PVC foam and we’ve got a gel coat on the panel as well which makes things interesting in terms of chipping the laminate now because the foam core construction as you can see the drill makes much lighter work as well the other tools but it does leave this chipping and fraying on the edges so going to demonstrate a range of different jigsaw blades in the jigsaw cutter starting with the most appropriate which is a perma-grit tungsten carbide gritty blade so it doesn’t have teeth instead it has a tungsten carbide gritted surface now that stops any chipping and fracturing of the laminate and allows us even on this phone call panel which as we say has got the gel coat which would be prone to chipping and delaminating we can cut that very nicely so moving on to a metal cutting blade this is slightly less appropriate but will still make a decent job of the cutting now a metal cutting blade has got much finer teeth than a wood cutting blade and so that means that when we cut although there is a small amount of chipping that happens it’s kept to a minimum and on a solid carbon fiber laminate you probably see very little chipping at all so moving on finally to the third type of blade this is a wood cutting blade and not one that we would recommend although we will demonstrate it and if you wanted you can still cut carbon fiber laminate with a wood cutting blade although it will chip and fracture at the laminate significantly more and certainly on this phone called panel though we’ve got the gel coat that’s going to cause problem so looking closely at it now you can see the size of the chips that are being taken out of the laminate makes quick progress but it’s really not not the ideal cutting blade at all and you can see that the fractures making quite a jagged edge so if we compare the inside cut on this piece that was done with the perma-grit blade then we’ve got the

outside edge on this one was cut with the metal cutting blade there’s just some small fracturing there and then finally if we look at this edge which was cut with the wood cutting blade you can see a lot of chipping and a lot of fracturing down that edge we’ve demonstrated there using a jig saw to make straight cuts but of course one of the main advantages to using a jig saw is the fact that it can make a very nice job of curved profiles or detailed sections like this and so there’s certainly a place for using a jig saw particularly with the right blade in like the perma-grit and still leave you with a nice edge on a cut laminate like this so earlier we demonstrated how effective the Dremel with a tungsten carbide wheel could be when cutting side carbon fiber sheet laminate well it’s even more effective when you’re cutting contoured shapes like this actual carbon fiber part where you’ve got a detailed edge to trim too and quite a sort of 3d shape to the part so we’ll demonstrate now just how close we would typically cut when trimming a part like this with a steady hand and sort of using the film as a guide on the part itself we can be within a fraction of a millimeter of the finished trim line and that of course leaves us with much less at finishing and tackling to do on the parts general like this making very light work of things like the slot that needs cutting at the top of this vent and if you look at the finished edge that we’ve got there’s really very little fettling to do afterwards and say just a fraction of a millimeter to take off this part so next we’ll demonstrate cutting some pull treated carbon fiber tube now because of the fiber orientation running lengthways all the fibers running lengthwise down the tube this does pose some interesting problems when cutting we just demonstrate using the angle grinder with the slitting disc and let’s pull through t-tube make a fairly careful cut through you’ll see that because all of the fibers are running lengthwise down the tube they’re very much prone to fracturing so one solution for this is to rotate the tube so that the slitting disc is always putting down on the fiber down through the material rather than potentially splintering off at the bottom so if you take a look at that cut compared to the one earlier you can see that’s much smoother and cleaner so following the same principle using hand tools we just mark up this tube using a hacksaw what we do is we cut small incision all the way around breaking the fibers at the outside of the tube keep rotating with the hacksaw and then finally once we’ve gone all the way around we drop down gently with the blade by cutting in this way and we pull off the masking tape you can see that we’ve got a perfect finish and we’ve eliminated any danger of splintering or fracturing the pultruded tube another example of where we might want to use this technique is cutting down this carbon fiber seat post now bike seat post like this again makes use predominantly of unidirectional material so we want to be careful again for fracturing in the same way that we were with the pull treated tube so we’re going to make that incision light incision all the way around the outside of the tube where we’ve marked it off with the masking tape so being careful to cut through all of the fibers all the reinforcement on the outside of the tube just a very shallow cut and then when we’ve done that we’re going to cut down through the material really tube itself so again using a metal cutting blade in a hacksaw just cutting it by hand as you can see with no special tools no special equipment but just following this good good practice we can make a very nice job of cutting through so just being careful cut off that material is holding it at the top and as you can see the cut edge very nice and smooth with no fracturing at all now that we’ve got the first cutting operation done on these various samples of carbon fiber material is to finish the edges by rubbing them back with an abrasive block so that we can get the the final contours in the case of the parts where we were using cutting equipment like the jigsaw blade with the wood cutting blade where the it’s chipped and fractured at the laminate which we anticipated we’ve got a reasonable amount of rubbing back to do on those edges now we can do that either using something like a perma grip block or another form of sanding block or we can just make a basic sanding block by wrapping some abrasive paper around a piece of foam or wood now sanding these cut edges is going to be another just generating operation so on with the respirator or dust mask starting off now using a perma-grit block this would be our favored way of finishing edges the block has two sides a coarse side and a fine side so we’ll start off using the coarse side of the block and very quickly we can rub back the edge even on this side to mill prepreg sheet flip the block over and use the fine side just to finish that edge and leave that really

quite nice and smooth so we’ve just rubbed back both of those edges on this part that were cut using the hacksaw and so in no time at all there as they should be so we’ll look next at the foam core panel that we cut using the various different jigsaw blades where we’ve got quite a lot of chipping so using a perma-grit block again starting with the coarse side and then turning the block over using the fine side makes incredibly light work of finishing an edge like this even there where we had quite a bit of chipping now of course if you don’t have a permit block don’t worry you can make a perfectly good sanding block by wrapping a piece of abrasive paper in this case we’re using a 120 grit around a piece of foam or wood and that will leave the carbon-fiber sheet with a nice smooth finish as well so sticking now with the two mill prepreg sheet but returning to take a look at this detail on the inside of this part that we’re making something like a perma-grit square file like this is absolutely fantastic for getting into these details areas particularly into corners and things but there’s also range of alternatives including flat files such as this all traditional files designed for metalworking would also be appropriate but will cut a lot slower than a perma-grit file so you can see that perma-grit sanding block on contoured edges like this trimmed apart makes very quick work of radius in these edges and then with the flat edges and the corner radius is out of the way we just go around the whole perimeter of Clarke using some rolls 120 grit wet and dried paper for this area where we’ve got the slot we’re going to use a flat file again like we used earlier this will allow us to keep the edge flat rather than introducing any wobble at while we rub it back and then just using the square file up in the corner allows us to get into that difficult to hard-to-reach section and finally again just using some rolled up wet and dry like we’ve done earlier allows us to put a very final finish on to this seat post that we cut back earlier the 120 grit paper that we’ve been using to finish all of these edges has left them all with a really nice smooth finish if you do need an even finer finish for example if you want to polish the edges up to a gloss then you can do so by using a 240 and a 400 finer grit papers the final consideration for our carbon fiber parts is whether or not we need any protection for the cut edges nine times out of 10 we would leave an edge exactly as it is and for most applications that will be perfectly fine however in harsh environments such as a marine environment then we might want to protect the edges against water ingress now one way to do this would be to lack of the finish parts in which case the lacquer will coat the edges and seal them but as an alternative you may wish to use some epoxy resin around the edge to seal the cut edge so we’ve mixed up just a tiny battery of epoxy because there really isn’t much that’s going to be required you could use just about any two-part epoxy laminating resin for this edge sealing but particularly any resins described as epoxy coating resins would be very suitable because they’ll always cure with a nice clean hard finish so just using a lint-free wipe to wipe it carefully around the edge of this part leaving it with a glossy smooth sealed edge I hope you’ve enjoyed this easy competence guide to cutting and finishing carbon fiber sheet and carbon fiber parts important things to remember are that with some basic safety precautions cutting carbon fiber can be perfectly safe and that secondly you don’t really need any particularly specialist tools or equipment in order to achieve a good finish some of the equipment that you have seen like the perma-grit tools are available on our website and we also have an excellent range of carbon fiber sheet angle and sections so if you do fancy having to go at your own carbon fibre project do check us out