Cutting kevlar cloth

[JohnRich 4]

Try and say that subject title 10 times real fast.

I've just finished applying a kevlar patch on my canoe, to strengthen a worn-out spot at the bottom of the bow, where I crash into too many rocks in shallow whitewater. (Photo 1)

The hardest part of the process is cutting a patch out of kevlar cloth. I tried three pairs of scissors; two from the household, and one from the shop. The latter has been advertised on TV as tough enough to cut pennies in half, but it won't cut kevlar. None of them would. Geez that stuff is tough. (Photo 2)

I ended up using a razor utility knife, and cutting while holding the edge of the fabric down tight against the workbench surface with a steel straightedge. And even then, it would take several passes of the razor to cut all the fibers. They would just sort of mash down into the wood under the razor blade, and not cut clean.

So, riggers, what the heck do you use to cut this tough kevlar fabric? Scissors made out of diamonds?

As for the canoe patch, now I'll let the resin harden, and go back with some sandpaper and paint to clean it up. Then it'll be ready for the Pecos River in October!

[ZigZagMarquis 9]

  Quote

So, riggers, what the heck do you use to cut this tough kevlar fabric?

We're not allowed to divulge such secrets to the public in general... soooo... I could tell you, but then I'd have to kill you and eat your brain...

[rushmc 23]

  Quote

Try and say that subject title 10 times real fast.

I've just finished applying a kevlar patch on my canoe, to strengthen a worn-out spot at the bottom of the bow, where I crash into too many rocks in shallow whitewater. (Photo 1)

The hardest part of the process is cutting a patch out of kevlar cloth. I tried three pairs of scissors; two from the household, and one from the shop. The latter has been advertised on TV as tough enough to cut pennies in half, but it won't cut kevlar. None of them would. Geez that stuff is tough. (Photo 2)

I ended up using a razor utility knife, and cutting while holding the edge of the fabric down tight against the workbench surface with a steel straightedge. And even then, it would take several passes of the razor to cut all the fibers. They would just sort of mash down into the wood under the razor blade, and not cut clean.

So, riggers, what the heck do you use to cut this tough kevlar fabric? Scissors made out of diamonds?

As for the canoe patch, now I'll let the resin harden, and go back with some sandpaper and paint to clean it up. Then it'll be ready for the Pecos River in October!

I never have had to yet but I suspect a hot knife will be the answer.

I, like you, will wait and see.

"America will never be destroyed from the outside,
if we falter and lose our freedoms,
it will be because we destroyed ourselves."
Abraham Lincoln

[DSE 5]

These work. They're used for cutting Kevlar for road cases/production.

[Jeffrey 1]

John,

Kevlar is easy to cut with most any sharp scissors if you get a hot glue gun and run a thin 1/4" bead of hot glue over the area you need to cut. We have been doing it that way since I come up with it. I love the look on Riggers faces when they first try it.

rushmc,

A hot knife will not cut it, Kevlar will not burn.

Jeff

[steelyeye 0]

Back in my kayak building and repair days, we found that a REALLY sharp pair of high-quality scissors was needed. Fiskars or the equivalent worked well.

Razor knives work too, and I would imagine that a rotary cutter would also work well.

"Better a has-been than a never-was. Better a never-was than a never-tried-to-be..."

[docdialtone 0]

Try a electrical or communications supply store, they sell ceramic scissors that are used to cut the kevlar in fiber optic cables. Graybar is one of the largest and have offices all over the country.

http://catalog.graybar.com/servlet/BugsEye?reset=T&cmd=login&username=guest&password=guest&mode=BugsEye&language=en-US&config=graybar_dot_com&variant=graybar_dot_com&query=Search&quicksearch=kevlar+scissors

[rushmc 23]

  Quote

John,

Kevlar is easy to cut with most any sharp scissors if you get a hot glue gun and run a thin 1/4" bead of hot glue over the area you need to cut. We have been doing it that way since I come up with it. I love the look on Riggers faces when they first try it.

rushmc,

A hot knife will not cut it, Kevlar will not burn.

Jeff

Thanks, I learned something today!

"America will never be destroyed from the outside,
if we falter and lose our freedoms,
it will be because we destroyed ourselves."
Abraham Lincoln

[denete 3]

Here is a tried and true method for light-weight Kevlar (probably not what you're using on your canoe). It really works well. Get a new pair of 9-1/2" Fiskars scissors. Run each blade at a 90-degree angle against a sanding belt, moving smoothly from base to tip. Do this twice on each blade. Surprisingly, that's all it takes to allow them to cut the Kevlar.

For your heavier weight Kevlar, there are some options on...

http://www.jaeberly.com/id7.html

...or Fiskars Titanium Nitride Coated series shears (gold colored blades).

- David

SCR #14809

"our attitude is the thing most capable of keeping us safe"
(look, grab, look, grab, peel, punch, punch, arch)

[everymansaved 0]

Well, I've yet to have to cut the stuff, but I'll be the first to say: Nice job on the canoe patch!

God made firefighters so paramedics would have heroes...and someone can put out the trailer fires.

[Broke 0]

I am not a rigger, but I do know of these scisors made for NASA. They are ceramic and they cut through everything. Even makes cutting bunker gear a breeze

Divot your source for all things Hillbilly.
Anvil Brother 84
SCR 14192

[Squeak 17]

  Quote

  Quote

So, riggers, what the heck do you use to cut this tough kevlar fabric?

We're not allowed to divulge such secrets to the public in general... soooo... I could tell you, but then I'd have to kill you and eat your brain...

That would not be a very saisfying meal, go check SC for evidence


I use a Stanley Knife to cut Kevlar

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[JohnRich 4]

Thanks to everyone for all your helpful replies. Since my need to cut kevlar is infrequent, I'm looking for a cheap option, rather than making an investment in something expensive that won't be used very often. So, with that in mind, I like the hot glue gun idea best. And since I've also had problems with the fibers fraying from the cut edge, that hot glue might also help solve that problem too. I'm going to give that a try.

Ceramic scissors - who da' thunk it! I'll have to keep my eye out for one of those, or a pair of Fiskars, for future work like that.

Re: my brains. Some people say I have known, so that wouldn't make much of a meal.

Thanks for the compliment on the canoe patch. It ain't that pretty, but I'm only worried about functionality. A little sanding and painting will make it match the canoe better. I'm ready to go out and whack some more rocks now.

[Jeffrey 1]

  Quote

I like the hot glue gun idea best. And since I've also had problems with the fibers fraying from the cut edge, that hot glue might also help solve that problem too. I'm going to give that a try.
>>>>>>>>>>

John,

It will also definitely help bond and hold the fibers. Just so it doesn’t have and adverse effect on the resin you use. I would make a test piece first.

We only glue one side, but you may also try applying it to both sides with that thicker Kevlar. Then scrape off the excess glue on the back side with a sharp tool prior to assembly for your application.

I have enclosed photos of one of the types of Kevlar we cut often using this technique. I was one very popular guy with the parts department when I discovered this trick many years ago, that’s for sure.

Hope it works for you.

Jeff

• Quote

[Spizzzarko 0]

Kevlar is not a really good patching material. If I were going to be making the patch in the boat hull I would use a mixture of fiberglass and Carbon Fiber. I would line the weaves up in a 45 degree angle on each layer to increase the strength. That is all.

[Rdutch 0]

When I used to build composite aircraft, we used Kevlar for reinforcement on some area's. They actually make kevlar shears, basically it was a zig zag scissor. From what I remember they were something in the area of $65 a pair. The hardest part was to not fray the material. Impregnated with resin and cured you could sand the stray fibers off. Also we used to tape the material on both sides before we cut it. Its been 8 years so my memory isnt the best. I do remember it was a lot harder to impregnate Kevlar with resin than carbon or fiberglass, I would use a brush to wet the area before I laid the kevlar, and then wet it after laying it.
You can also buy Kevlar pre-preg strips in different widths. this is a little easier to cut to size, and a lot easier to work with, but also a lot more expensive. The advantage of this method is you dont need to buy resin, mixing cups, ect.

Good luck.
Ray

Ray
Small and fast what every girl dreams of!

[denete 3]

That does bring up a good point. If you are doing a pure Kevlar layup, you may want to consider putting a layer of fiberglass on the outside of the layup. That way, any sanding that you do after curing will stand less of a chance of sanding into the Kevlar. Kevlar doesn't sand down well, it just fuzzes and looks like crap. So, throw a layer of 3-4 ounce glass on the outside of the layup.

One other method that I've used for cutting .75 ounce fiberglass that might also work with your cutting is to dust it with 3M Super-77 adhesive and then lay wax paper onto that dusted piece. Dusting means to spray it into the air over the fabric, and not directly onto the Kevlar. Once the two materials are together, you have a backer that allows you to cut without disturbing the weave.

- David

SCR #14809

"our attitude is the thing most capable of keeping us safe"
(look, grab, look, grab, peel, punch, punch, arch)

[JohnRich 4]

Thanks again for all the great tips.

I canoed a 14-mile stretch of the Brazos River, west of Houston, on Sunday. The kevlar bow patch held up well so far, jamming it into sand and gravel bars in river bends, when beaching to take a break.

Photo: me with turtle friend.