Cutting kevlar cloth

OK, who has the secret ?

I tried sicssors, a brand new xacto knife, a single edge razor blade and several other ways, and nothing wanted to work.

“The bride” finally was able to get it done after much anguish with the heel of a pair of scissors.

I have to cut another patch out, and sure would like a easy method.



I think…
…I remember something about good pinking shears but it plays hell on the shears.

If it were easy it wouldn’t be Kevlar.

Good luck.

sweet composites
they sell some scissors but my take is that you start with high quality razor sharp scissors. So if you bought some scissors sharpen them first.

High Quality Pinking shears…
the kind of scissors that cut a zig-zag line are the way to go. But be warned…they will require pre-sharpening and more sharpening as you go along.

Once I finished cutting cloth for my Pirough…I bought my wife a brand new pair. They will be pretty much worn out by the time you get done with them.

I use a cheap pair of office scissors,
that have rather rough edged blades. I use short cutting strokes, well back in the jaws of the scissors, near the hinge, and with each stroke I pull back slightly. Probably this little back pull helps the rough edges of the cheap scissors to grab and cut the Kevlar fibers. I can produce nice bias-cut patches with ease, though I admit that the process is time consuming.

Jack and all … Just get a new
set if Fiskars (sp?) or even the genreric red handled knock offs of the Fiskars. Use them on the kevlar only 'till you are done with your project.

The new scissors will cut at least 36 lineal feet cleanly before you have to fuss wiith them.

We go through a lot of them but just shift them do different dutys as they get used.

The red ones work just as long as the triple price Fiskars.

You can trim thr kevlar when its ‘green’ too but you have to babysit it and have to wait to cut it a little longer than you would normally with glass or carbon.

You can also mkae you life easier by laying a ply of 4 ounce glass over it when doing repairs.

Call me if you want.

EZ Cutter

– Last Updated: Sep-20-07 9:52 AM EST –

it's possible to "gum" your way thru kevlar with a pair of scissors but the professionals use an EZ Cutter.

A rotary cutter from your local
fabric store and the matching pad works great, at least on fiberglass. Come on down and use my wife’s.

Fiberglass cuts easy
Your “bride” won’t be a happy camper when I dullen her cutter on some kevlar.

I even experimented by laying the kevlar on a piece of wood, and tapping a brand new single edge razor blade with a hammer to see if I could chop through the strands, and all it did was push them down into the wood without cutting them.



Those power nippers work good
but still lose effectiveness in a short time on kevlar.

The Fiskars clones really do work great and less $

Razor blades, rollers, X actos just make a mess of the weave and cause one to take chances with too much pressure.

I am curious Pat…
do the loose kevlar strands make a good filler when mixed with Epoxy for filling a hole or something like that?

I was thinking of doing that on the very inside of the bow of the comp cruiser where we punched a hole through the other day. It won’t show so I don’t care if it looks ugly. I put a kevlar patch on the out side.


chopped kevlar
I have seen chopped kevlar sold for filler material. Get as fine as you can, 1/8" or less.

I have used 1/4" chopped fiberglass in some filets and it’s a mess going on, but once cured it’s sandable, kevlar isn’t.

JackL, you need to get some S-glass
and not use Kevlar for outside repairs. Although I do not believe reports that Kevlar, once exposed, wicks moisture throughout, it DOES absorb water, it does fuzz, it does not have good compression strength, and for these reasons it is not a good cloth for outside patches. Use it for inside patches, where it is unlikely that you will scuff through the resin and expose or fuzz the Kevlar, and where its great tear resistance is maximized in effect.

Too late !
The patch is already on, and came out far better than I ever expected.

I thought it would be slightly bulging out, but it came out looking as if it is part of the original kevlar, (very smooth)

The edges of the hardened resin out beyond the kevlar needs a little sanding, and there is one slight indent where the original hole was that I can put another bit of resin in.

I think my success was the use of saran wrap tightly duct tapped over the patch.

I thank you on the “sanding tip” though. I’ll make sure to keep away from the patch.



Hey Jack, sorry to not get back
to you right away.

Just about anything you chop up and jam into the bow/stern keel ‘pointy ends’ will be fine for an isotropic block … generally the resin will be the larger part of the mix anyway. Gotta be beware excess heat if it is over 1/2" thick though. If you are thinking you will actually wear throught he original laminate, better to use cloth.

Due to kevlars super resistance to abrasion ( fuzzing aside) I would always put two + plys of it inside the very ends of my boats (no matter what the lay up) as a sort of ‘indicator’ of things wearing down but it would hold up great and keep the boat together if one had to drag it far in an emergency.

Nice to put a couple( kevlar ) plys inside but also nice to tape off just ‘around the corners’ on the very ends of the bow/stern keel sections and lay some glass outside if the boat is going to see a lot of wear and tear.

Let me know if you want some labor saving tips on building things up here fast while keeping the boat fair.

cutting kevlar
For others reading this string (now that the original project is finished), you’ll find that Fiskars is the (or at least a) right answer, but you’ll have an easier time of it if you find a pair of their poultry shears, as opposed to regular scissors; they are powerful little devils. There is also a terrific little thumb print shaped (and orange, of course) Fiskars sharpening tool that will re-edge the shears quickly and efficiently if they need it after a few passes of the kevlar.