Cutting Carbon Fibre sheet

[transatlantic]

I want to to cut some 2mm thick carbon fibre sheet to a specific shape (from a template). After cutting the rough shape with a jigsaw, is there any way a router with a bearing bit can be used to follow a template to get it spot on?

Is there a specific bit for this kind of thing? I only need to cut an ellipse from an A4 sheet, so the bit doesn't need to last long.

 

[Racers]

I would be wary about using a router you need very good extraction for carbon fibre, its conductive and an irritant.

https://news.nilfiskcfm.com/2017/04/5-h ... facturing/

http://www.carbonfiber.gr.jp/english/ma ... afety.html

Pete

 

[worn thumbs]

As has been said,carbon is conductive,although being part of a resin/fibre matrix with a resin that doesn't conduct does reduce the risks a bit,you really do need some extraction.A good workshop hoover will be adequate and a dust mask is sensible.Actually cutting the carbon isn't difficult but don't expect the cutter to be much use afterwards.
The OP didn't say -and may not know-exactly what type of material he is dealing with.Hopefully it will be a well cured epoxy laminate and at best made from prepreg.If he has the misfortune to work with a relatively "green" polyester laminate things are not quite so good.It may well soften and allow the edges of the carbon to fray slightly.In which case a couple of days in a warm airing cupboard or green house will be an improvement.

 

[transatlantic]

Thanks for the advice. I was definately going to use dust extraction.

As for the material, I was just going to pick up something like this :
https://www.ebay.co.uk/itm/Black-Carbon ... amzvXRPAhA

I have decided that I probably don't need the accuracy of a template. So won't be using a router. Will just use a jig saw (with a specific cutting blade for plastics) and a file.

 

[Racers]

Thanks for the advice. I was definately going to use dust extraction.

As for the material, I was just going to pick up something like this :
https://www.ebay.co.uk/itm/Black-Carbon ... amzvXRPAhA

I have decided that I probably don't need the accuracy of a template. So won't be using a router. Will just use a jig saw (with a specific cutting blade for plastics) and a file.

Mask and extraction?

Pete

 

[transatlantic]

Mask and extraction?

Pete

Yep

 

[Racers]

Mask and extraction?

Pete

Yep

 

[worn thumbs]

That link leads to carbon effect ABS.So the conductivity aspect does not apply and there are no fibres to cause respiratory problems.Even better,the stuff won't have much effect on your cutting edges.If you are happy with a jigsaw cut edge my choice would be a fine metal cutting blade Say a Bosch T118G.A router would leave a neater edge and wouldn't suffer damage but you might need a fairly slow spindle speed to avoid a chunk of the swarf fusing itself to the cutter.

 

[AES]

Yeah, I think the "punch line" lies in the CARBON EFFECT ABS sheet in the ad you linked to. AFAIK, this is not carbon fibre sheet at all, simply ABS plastic sheet (which is quire soft BTW) "tricked up" to look like the real carbon fibre sheet you see used on aeroplane structures (before painting) and in the cockpit of posh cars.

As such you don't need any special cutting tools - by hand a coping or jeweller's saw with a fine blade, or even better a pair of shears with an "anvil", like for example, the Eclipse "Goscut" tool. For machine tools, a scroll saw with a fine blade would be great, ditto a jigsaw with fine blade. The most important thing if using a powered tool is to keep both speed and feed rate low - being a soft plastic the biggest "danger" is overheating, leading to the cut edges fusing back together again just after the blade has passed by.

And it it's only straight lines you need to cut, a stiff sharp knife to score the line/s then snap off afterwards should also work well (and no risk of overheating).

 

[transatlantic]

Ah crap. I hadn't even noticed that!

How can I tell if the stuff that I am replacing (which looks like that) is carbon effect or the proper stuff?

 

[AES]

If the stuff you're replacing is still to hand, and you don't mind cutting a bit (close to an edge), then try cutting a small piece off. If it's real carbon fibre sheet then you'll find, A) it's VERY tough to cut, and B) the cut edge should display some small "splinters".

Be very careful with those BTW, they're VERY stiff and sharp and if you get a bit into your finger it'll A) hurt like hell, and B) be quite difficult to get out (DAMHIKT)!

Where is the original? Is it in any way structural, or is it just (for example) a fancy looking cover over something? If structural then the chances are it's the real deal, if just there for looks the chances are it's some sort of plastic tricked up to look like carbon fibre.

The real deal is still very expensive, and if you do cut a new edge you should be able to see where it was originally "laid up", using thin layers of pre-impregnated sheets ("pre-preg") with the fibres going at either 90 or 45 degrees to each other (then baked under pressure in an oven). A bit like ply wood really.

If the article it came from was quite expensive when you bought it the chances are it's the real deal. If cheaper, most likely not.

HTH

Edit for P.S. Does it really matter if it's the real deal or not? If not an integral part of a structure (i.e. if it's just there for looks) then I would stick with the tricked up ABS you linked to.

It's cheaper than the real deal, and a lot easier to cut and handle. The real stuff is, AFAIK, still only/mainly used in aeroplane structures, F1 cars, Ferraris & McLarens, racing pedal bikes, and the like.

That's 'cos it's still high cost, quite difficult to use and shape (as above), requires a heavy initial capital investment to make, needs a "clean room" to make it in, and really "only" offers the benefits of extremely light weight and stiffness - i.e. ideal for applications like those mentioned above.

 

[transatlantic]

Ah - thanks for the info.

They're side guards that I want to replace on a old wheelchair that aren't made any more. The ones used on newer chairs sell for around £200. So asside from the extortionate disability tax, I'm guessing they're the real deal. They're not structural, but will get bashed around a lot, so the plastic needs to bend rather than just shatter. Is the material I linked to going to have some play? or just shatter?

For reference, it's this kind of thing https://www.dmehub.net/TiLite-Carbon-Fi ... l-cfsg.htm (from the description, they sound like real CF)

 

[novocaine]

the ones you link to are real CF. they really don't need to be though. they are cut from sheet stock rather than laid up and are only really for the look and being able to claim you have CF parts, I wouldn't waste my time with them or trying to mimic them, you can make something far more durable from a sheet of aluminium that will do the job and be far more robust, or HDPE if you want plastic will be perfect and wont shatter or cause any damage to stuff it hits.

I got given set of CF heal guards for the bike that were made in the same way, simple flat sheet cut out, it's the cheapest form of CF. I gave them away, completely pointless and really just for the look, no were near as robust as the aluminium guards I already had.

 

[transatlantic]

For me, the look is quite important so that it matches the rest of the chair. I don't care about weight. Bu they do need to be shatterproof. So would the original ebay link suit do you think?

 

[novocaine]

ABS will bend before it breaks. it won't last as long though and will bend easier and stay deformed (reaches plastic deformation quicker than epoxy resin of really CF which remains elastic, so returns to original shape)

same stuff as lego is made from. goes white when its strained excessively.

 

[novocaine]

real CF sheet can be had.

example
https://www.ebay.co.uk/itm/3K-Carbon-Gl ... SwrWZZ3ahR

can be cut with a sharp knife and patience.

 

[AES]

There are at least a couple of members here who know MUCH more about plastics than I do, (having been professionally involved) and perhaps they can advise on a plastic of suitable "toughness/bend-without-cracking" ability to make a replacement from.

I do however agree with the posters above that apart from the "sexy, high-tech" look, there's little point in using the real deal on those covers. I also agree that the covers look like the were simply made from flat sheets (made as per my post above) and NOT moulded into some curvy 3D shape before "baking".

So if the look is important to you I would SUGGEST (not KNOW please note) that ABS is quite a tough and tends to flex before cracking, so the original ABS CRF look alike that you first linked to, or perhaps a thicker version of the same stuff (?) would do the job much cheaper than those real deal covers you just linked to.

Also please note that a number of modern cars now have "bumper" mouldings, wheel arch mouldings, etc, made out of some sort of plastic, the advantage being that they too tend to flex rather than shatter if hit, and are apparently cheaper and lighter than their sheet steel equivalents. But what precisely that plastic is I don't know. As above you need, you need some expert advice and when it comes to plastics and that ain't me, sorry.

Note that if you do go the plastic route, "special" plastics such as ABS need special adhesives. Again seek expert advise.

Good luck with it anyway.

 

[worn thumbs]

real CF sheet can be had.

example
https://www.ebay.co.uk/itm/3K-Carbon-Gl ... SwrWZZ3ahR

can be cut with a sharp knife and patience.

Rather you than me!At the very least a fine hacksaw blade will do the job.ABS is a bit flexible and if the appearance is near enough I would go with it.Its less hazardous to health than real carbon and won't make you itch after cutting a piece.If it proves to be too weak after a spell of use,you can upgrade to real carbon but in all honesty most carbon seems to be sold for appearance reasons and properly engineered carbon structures are pretty scarce.

 

[AES]

Also note that the real stuff novocaine linked to is "only" 0.5 mm thick and costs over 11 quid. The ABS look alike that the OP linked to is, I think, 2 mm thick and costs about 2 quid if I remember correctly.

Re cutting the real stuff, I've had little hands-on experience (the new Airbus and Boeing models which are "99%" CRF were just coming in as I was going out of the industry to retire - previous generation Airbus and Boeing aeroplanes I experienced had "only" secondary structures and fairings, etc, made of CRF and other composites). So I didn't handle it very much (and as I got more "senior", my job was anyway mainly "watching" others.

BUT what somebody said above about being careful with splinters and slivers etc, when cutting is spot on. Cutting with a knife MAY be OK if it's thin flat sheet, but even then, if you're unlucky, offcut bits can be REALLY sharp and they HURT LIKE HELL in yer finger (as said before, please DAMHIKT)!

The aviation people who deal with this stuff every day in finished state use special gloves, made from, I think, Kevlar (in it's "raw/uncooked" state it's quite benign). But a small splinter of finished state stuff is VERY sharp (as bad as grabbing a handful of SS swarf off the lathe!!!) and a bit in your eye would, I image, be VERY dangerous indeed and need instant medical attention.

Personally, I liked the suggestion that came up quite a few posts above - "use ali"! But then I'm an old-fashioned, stick in the mud sort of cove.

 

[GarF]

Could you lay up the exact shape you want yourself? The carbon cloth is fairly easy to cut and the laminate can be trimmed closer to final shape with a sharp knife once the epoxy has gelled but is still green. This way you could probably minimise the amount of finish cutting involved. As others have said the splinters that come off when cutting carbon laminates are nasty and go everywhere. I made a dinghy rudder blade from cedar and sheathed it in carbon last year and trimming the excess carbon at the trailing edge was the least enjoyable part of the process by far. I found for the most part that the easiest method was simply paring away at the edge with a chisel (which needed stropping/honing frequently). I was using a 0-90 cloth so it was kind of like working on super brittle plywood of only 1-2mm thick. It was tedious work but at least there wasn't so much airborne CF. Block plane works too, but the sole will never be the same again.