Anyone experienced with Carbon Fiber?

[DRJ1014]

Im wondering if anyone has had any experience cutting and or using carbon fiber?

I am doing some research and want to try to build a carbon fiber computer case. There is one out now but costs around $900.00 and that... well is pretty expensive. I can get sheets of of carbon fiber for much cheaper than that.

The only problem is im not sure on how to go about cutting it into the sizes and pieces im going to need, if there is a special way I have to cut it (using a water cutting method etc)

Any input or advice would be greatly appreciated.


I have talked with some of my friends and they are just telling me to buy an acrylic computer case and take it apart and just use a carbon fiber vinyl but it just wont be the same

 

[Kil4Thril]

To properly use CF, it needs to be laid/molded in a manner very similar to fiberglass, then cured using an autoclave. If you're buying cured sheets, realize you'll be stuck with only flat surfaces. Also, when cutting, the dust/fibers can be extremely irritating- though I don't know if it is harmful.

 

[LibertySyclone]

To properly use CF, it needs to be laid/molded in a manner very similar to fiberglass, then cured using an autoclave. If you're buying cured sheets, realize you'll be stuck with only flat surfaces. Also, when cutting, the dust/fibers can be extremely irritating- though I don't know if it is harmful.

All true, with the exception of the autoclave, it just needs to be heated and or vacuumed to get the air out. its just like fiberglass. (obviously aircraft and other high strength items are different)

if you have a case you like, reverse mold it with something like plaster, then positive mold it with the carbon. Thats the closest you would get unless you just wanted to do overlays on an existing case

 

[alg7_munif]

It is hard to get a perfect straight line if you cut the cured panel with a dremel because of the fibres but it is possible to cut it.

 

[Michael Daly]

All true, with the exception of the autoclave,

Whether or not an autoclave is required is dependent on the type of CF+resin that you use.

Pre-preg (CF with the uncured resin/epoxy added at the factory) will not cure at room temperature. This stuff needs to be autoclaved so the heat will cure the resin.

Plain CF fabric without impregnated resin will require you to use conventional resins or epoxies and add them during layup. These will normally cure in a relatively short time (work times maybe 15-20 minutes to a couple of hours, full cure times 24 or more hours). Specialty resins can be used that will cure with heat or UV exposure etc, but these are hard to get retail.

If you want to make up your own sheets from fabric plus resin or epoxy, then get plain CF fabric, cut to size (just like a fabric with good scissors) saturate with resin/epoxy and lay into the mold (which could be a flat surface covered with a mold release material such as poly vinyl alcohol (PVA). Covering it with a release film will allow you to get a smooth surface - work the bubbles out by hand. Vacuum bagging it will remove the excess resin and give a smooth surface, but is overkill - save that technique for the racing version of your case.

If you are going to buy pre-made sheets and cut them, use a long straightedge guide and get a cutting head (like a mini-power saw) for the Dremel so you get a clean line. Watch out for the dust produced - the jury is out on just how dangerous it is to breath.

Pre-made flat sheets are fine if that's all you need - it is a lot easier to just cut a sheet than layup. Wear a good dust mask, eye protection and gloves regardless of which method you choose.

There are good books on fiberglass/CF/Kevlar/composites in general. Gougeon Brothers have a fine book. Do a little homework.

 

[DRJ1014]

Would it be possible to use a Water Jet to cut the CF? I have seen it used on steel in the past at my buddies shop

 

[Doggeh]

Check out http://custompc.co.uk/blogs/doggeh/2008/05/22/finished-fibreglass-case-build/

I made myself a full fibreglass case and carbon fibre will be very similar to this. Cutting sheets of carbon fibre is very simple and can be achieved with a jigsaw/bandsaw or even a handheld hacksaw - no need to bother with wet cutting at all. The cut edge will need sanding back smooth so you'll need to cut the panels oversize.

My case was a moulded single piece so you'll need to think carefully about how you'll join the flat panels together. The joins will most likely need to be covered because they're unlikely to be very tidy.

Also the thickness of the sheets is a consideration. My case is approx 2mm thickness which is nice and sturdy while remaining easy to cut. Flat panels will be flexible so you'll need to construct them around a solid frame (with a couple of crossbars depending on panel size).

 

[westrock2000]

Also if you plan on using resin, make sure its in a well ventilated area, like a garage with the doors open (and possibly a box fan). First time I ever fiberglassed I, stupidly, did in the kitchen and had a really terrific headache about 2 hours later.

Molding stuff is really pretty easy and for most stuff you dont even need a vacuum or anythng like that, but since you mention CF, you probably want the weave to show and a glossy finish and that is where the hard work comes in. Thats why CF stuff usually costs so much more then the same fiberglass part because with fiberglass they just sand it smooth, paint it, and call it a day.

 

[Michael Daly]

Resins like polyester and vinylester contain styrene and the styrene offgasses during mixing, layup and even after it's cured. That's what give the "new fiberglass" smell. You don't want to breath that stuff. westrock2000 gives important advice - work in a very well ventilated area. You can also wear a face mask with filter rated for styrene.

Epoxies, especially some of the better quality marine epoxies like West Systems, offgas very little and don't smell very much. You should still work in a well ventilated area just to be safe. Marine epoxies will cost about 3 to 5 times what resins do but are much stronger.

 

[Somnambulator]

West Systems-grade resin kits are overkill for anything PC-related. plus costing twice the standard resin kit makes it not the most economical choice either.

i dont know anything about carbon-fiber. i didnt even know it was laid out like fiberglass, though it's quite obvious now. i wouldnt really use a dremel to make precise cuts on kicked glass/FC. you'll probably want to use a band saw or even a hand circ saw depending on the size of the sheets.

 

[xb1]

I would go with something like the Slimar 249 Clear Polyester Resin for anything non-load-bearing like a computer case. It sets ultra quick, which is the downside to using polyester resins, but its fairly cheap and looks good when molded. And one should really use a respirator while cutting FRP or CFRP. The fiberous dust will cause lung problems over time, or contribute to any that already exist. Basically if you already have a respirator for resin curing, then make sure to have a fine particle filter on it before you cut or sand it. I've found that rough cuts with tools like tin snips or cutoff wheels are the fastest way to get the approximate shape you want. Afterwards, do the details with a fine carbide bit and a dremel. FRP and CFRP cut much quicker than metal, so if you're used to modding sheet metal or aluminum cases, I would suggest to keep the tool speed down. And for cutting a straight line, I would get a table saw with a fiber-reinforced cutoff wheel if you happen to not own an automated fabrication facility where robots do the cutting for you.

 

[Mach42]

When cutting CF, you have to be careful while cutting so that the edge won't splinter or delaminate. I'd suggest using a straightedge with something like a couple small vices to put some pressure on the back side of the cut (determined by the direction that the cutting blade rotates) to prevent this.

 

[xb1]

Thats especially true if you do the layup yourself. Prepreg tends to have less issues with splintering, but it never hurts to play it safe.

 

[Langer]

My father's company makes most of the carbon out there (factories in Canada, China, USA, Germany) and imho the best choices are either the 'dry-cloth' idea, or use carbon panels cut to the precise size of each side, then hold it all together with metal brackets; this method would work best with a design that had only straight flat sides.

However if your design is complex and needs bent/formed panels thermoplastic[sup]1[/sup] panels can easily be reheated for vacuum forming, etc. Unlike thermoset[sup]2[/sup] panels which once set are very hard to reheat and reform - and in may cases cannot be reheated.

The panel idea would be easier to construct because it wouldn't need you to make molds and forms from which to mold the carbon pieces, also it doesn't require you to use potentially harmful plastics/resins. All you'd have to do is cut the shapes and bracket the corners to hold it all together.

1: thermoplastic uses resins made of: polypropylene, nylon, PET or polycarbonate
2: thermoset uses epoxy or polyester resins.



The following are images of examples of what can be created with various carbon fiber weaves, coloured resins, and carbon/fiberglass weaves. In all the images below (save for one or two samples) the only fibers used are Carbon and Fiberglass, colours are added with resins.

In these examples you see Thermoplastic panel samples:

First two are thermoplastic the rest are thermoset:

Here we have carbon fiver panels that have had a fabric (could essentially be any fabric, I've even used old tee-shirts in the past) layer pressed ontop:
These are thermoplastic examples - these are easily reheated and easily vacuum formed.

In this example fiberglass has be impregnated with colourd resins to make perdy colours:
These are unidirectional tape, traditionaly several of these are welded together to make panels ~40"x40". The panels are layered on top of one another in a 0-45-90-0-45-90 etc pattern to the desired thickness.

The following are just cool examples of where I've used these products in the past:
crazy thick, virtually indestructible, carbon panel:
Several dozen layers of the above unidirectional design pressed in a heated press at several thousand tonnes.

Vacuum formed curves:

A carbon fiber skateboard:

some of you may have seen this before - this is the cover from the Acer Ferrari laptop:

Here is my latest creation, this sheet was made with fabric that was impregnated with resin; the panel was then placed in a heated press (~450 degrees iirc) and squeezed at several thousand tonnes.

Another example of indestructible uber panel. This item was designed for armor plating for a military application for the US - I'm using it as case feet and SLi brackets. Hahaha.

Panels can be cut with a thin saw blade on a table saw or chop saw - but it will dull the blade fast as Carbon Fiber will be harder than the blade. You can use a jigsaw, but a band saw or scroll saw (for thin pieces) is recommended. A dremel will get the job done but the cuts wont be as pretty.

I'll highly recommend scotch-bright pads for the edge clean up after sanding, they work wonders.

depending on what resins you'll be using I suggest researching the Material Data Safety Sheet for the plastic (MSDS) - as for the Carbon dust, it's itchy but realatively harmless.

Goodluck!

 

[GeorgeHR]

As I recall poyester resins do not work well with carbon fiber. Epoxy works much better.

Prepreg that sets at 350 degrees can be cured in an oven.

Epoxy is not real nice stuff. One should limit the amount one breathes. Work outside.

Carbon fiber is very stiff so it does not stick to curves as well as fiberglass does. It is best to mold over convex surfaces. In which case tension is sufficient to pull the carbon fiber into place.

 

[Michael Daly]

Epoxy is not real nice stuff. One should limit the amount one breathes. Work outside.

While epoxy is not perfect and you should work in a well ventilated area, modern epoxies, such as marine epoxies, are safer to work with than other resins such as polyester and vinylester.

The hardener in epoxies is an allergen. You can develop an allergy to it over time. Make sure you use good gloves (I prefer nitrile to latex) and a avoid skin contact. Once the epoxy is cured, it is no longer a problem.