cutting composites

[J. Schmidt]

What's the best way you've experienced cutting composite layers? With my first experience last year with carbon/Kevlar I found it more difficult to cut than I thought. Patience and a good pair of scissors seemed to go through the raw kevlar pretty good, but what do you recommend for the final product. Is there a good way to get a clean, straight cut withought too much fraying?

[J. Schmidt]

What's the best way you've experienced cutting composite layers? With my first experience last year with carbon/Kevlar I found it more difficult to cut than I thought. Patience and a good pair of scissors seemed to go through the raw kevlar pretty good, but what do you recommend for the final product. Is there a good way to get a clean, straight cut withought too much fraying?

[Schulberg J]

A cut off wheel worked pretty good on the finished product.

jason

[Michael Jones]

Best bet is to create an edge in the fabric by pulling both sides away from the cut line while cutting. If possible, cut more than you need so whatever frayed edges result are off the finished product.

Once layup is complete, a cut off wheel easily chops off frayed edges and is equally good for shaping. I find Kevlar in particular to be wickedly toxic to cut with a cutoff wheel though - it's the only odor in our composites room that gets me loopy. Wear a mask, do it in a ventilated area, or enjoy the cheap high. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Kevlar weave in particular is difficult to cut cleanly. I've gouged a few holes in my fingers trying. We did buy Kevlar scissors once but they weren't all that more effective than $1.99 K-Mart blades and were quickly gummed up by epoxy. I'd stay cheap and wear padded gloves (bike gloves work well) to minimize damage.

Gloves and skin protection also helps with CF splinters, which have a tendency to embed themselves in you for weeks on end. Stubborn little buggers.

[steve d.]

the number one most important thing is...

WEAR A MASK when cutting the finished product.

a good heavy pair of fiberglass scissors/shears usually do the trick when cutting the weave.

becasue carbon fiber is exactly that, and the human body is made from carbon, you won't just cough it back up like fiberglass. get enough in your lungs and you die.

sjd
who wears a mask when fiberglassing too...

[MikeWaggoner at UW]

If you've got a good surface, they make composite cutters that look like pizza cutters. I was suspicious at first, but they worked excellently.

[Denny Trimble]

Yeah, Jessica uses one of those for her quilting projects... very similar application, slightly less irritating materials http://fsae.com/groupee_common/emoticons/icon_smile.gif

[J. Schmidt]

When I tried a cutoff wheel the resin just melted and let of some noxious odors; when I tried to speed up the kevlar wouldn't cut. This was my delema. What seemed to work best for me on the final weave is a new pair of sheet metal snips, making 2 cuts. One about .5 inches outside the finished line, and one finish cut. Lots of masking tape over the line helped too, like cutting laminate. Thanks for the info guys.

[SkiEricSki]

The Kevlar makes things tricky. Best thing if it's practical is to use a diamond saw and cut it wet. Even with this the kevlar will probably fray some.

[Jon Huddleston]

For the finished product, I always use a diamond blade dremel cut-off tool. Costs about 20 bucks but is the only tool I have used in the past couple of years for finish cutting of solid carbon or carbon-nomex honeycomb. Don't use it for steel/alum. etc, it will destroy the cutting edge! For the uncured prepreg use a standard utility knife or regular scissors for non-prepreg and glass.