cutting Kevlar

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Bill1170

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Dec 20, 2007
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While working today I damaged a special vacuum connector for a saw I use to cut masonry. After work I examined the damage. The part is a thin tube molded from glass-reinforced plastic, probably FRN, which angles into a plate that directs the dust to the port. I cracked the thin tube in two places near the open end while setting the saw on its side carelessly.

My first thought was the rough it up and use some glass cloth and epoxy to effect a repair. Then I remembered that I had purchased some 6" Kevlar reinforcing fabric to use as an abrasion guard on a postponed sign project. Yeah! Let's use Kevlar!

So I get the roll of Kevlar cloth and go to cut off a 6" strip, from which to cut a narrow strip with one factory woven edge to avoid sharp points at the open end of my tube. Grab scissors, cut fabric, easy - right? Wrong. Scissors won't cut the stuff, it just forces the blades apart and slides between them. After several tries I move to some Fiskars multipurpose shears that cut paper, cloth, and sheet metal. Same problem.

How about a knife and a straightedge? Utility knife with bimetal blade and steel ruler on workbench, heavy pressure, cuts partway through. Raggedy. Heavier pressure and I am through, but at the cost of a 1/8" deep scar in the bench.

Now I do the second cut and figure what I need is extreme slicing action to part the fibers. So I place the square of cloth on a paint stir stick to save my bench and slice with my shaving sharp Rat 1 folder, using the belly of the blade to slice back and forth with increasing pressure, guided by the steel ruler to the side of the blade. I split the paint stick in half without getting through the Kevlar. So I go back to the utility knife right on the bench and get 'er done at the cost of another wound in the bench top.

The repair went well and will be stronger than new when fully cured. I think I need a pair of Kevlar shears. I think the edges on those are zirconia ceramic.

Anybody here have experience cutting this stuff? What works for you?

Bill
 
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Kevlar is really rough on the edge of a blade, I would be guessing that your rat1 was about as sharp as a butter knife when you were done? Unless you have the scissors made for cutting kevlar or a very sharp knife with really good steel like S30V or S90V kevlar can be a real b!$@h to cut.
 
Knifenut,

I did not have time to check, but I suspect the Rat needs a little TLC after its run-in with the Kevlar. Have you cut Kevlar with an s30v knife? How did that go for you? I had the thought to try my SE Pacific Salt, but I don't want to ruin the blade!

If nothing else, Kevlar provides a test of knife steel that is pretty severe. Seems it would separate the contenders from the pretenders pretty quick.

Bill
 
Kevlar shears only cost about $20. They look like tin snips to me so if you have a pair of those... I have also heard that EMT shears will work in a pinch.
 
A place I once worked for bought a large order of "cut resistant" Kevlar gloves. Everyone thought it was THE cure for hand cuts on the job because nothing can cut through Kevlar, right? Wrong.
I laid one of their wonder gloves on the desk, took out my Spyderco Dodo and made a nice deep gash across the palm of the glove.
Oddly enough, I didn't make any friends in management that day. Sheesh! Go figure...:rolleyes:
 
I've used S90V and CPM-m4 to cut carbon fiber/kevlar weave, faired really well considering it was going through CF too. I also cut plain kevlar but didn't have enough of it to really effect the edge.
 
i cut up old kevlar gloves messing around with the knives i make. i can sharpen scissors to cut kevlar also. i have a small pair of fiskars that eats the stuff up.
 
It sounds dorky, but those "cut through a penny" ginsu-type shears work ok on Kevlar, since they have little tiny serrations.
 
misque said:
A place I once worked for bought a large order of "cut resistant" Kevlar gloves. Everyone thought it was THE cure for hand cuts on the job because nothing can cut through Kevlar, right? Wrong.
I laid one of their wonder gloves on the desk, took out my Spyderco Dodo and made a nice deep gash across the palm of the glove.
Oddly enough, I didn't make any friends in management that day. Sheesh! Go figure...:rolleyes:
Click to expand...

Ummm I kinda did the same thing a few years ago when my father brought home a few pairs. I said "wow, cut proof". So like a jackass kid, I put one on and ran a box cutter across the top of my hand. They were not cut proof and I left myself a nice 2 or so inch slice on the top of my hand. Luckily it didnt cut that deep, And thank God Dad didnt see me do it, I think he would have crapped his pants after witnessing such stupidity.
 
Seems like people don't really think about it very hard... Nothing can cut Kevlar, of course, so maybe all the factories that use kevlar fabric used to make gloves, boots, vests, helmets, webbing, etc. must use magical fairy wands to cut the cloth...
 
my roommate cuts the stuff all the time, he just uses an old pair of sheet metal snips, seems to work fine
 
Here is a follow up post.

First off, the edge on my Rat 1 folder is none the worse for wear after trying to cut the kevlar. It is still razor sharp, but did not cut the kevlar.

Second, I searched deeper through my scissors and found a large pair of Fiskars shears that cut the kevlar just fine. These shears have small serrations on both blades, and that seems to do the trick. They hold the kevlar fibers so they cannot run away while the other blade shears it off. The other scissors were sharp, but the serrations were only on one side of the multi-purpose snips, and too fine to hold the fabric still long enough to sever it. My other scissors were double plain edge, and hopeless on the kevlar despite being sharp.

If I use a knife again, I will pick a harder backing surface to cut into. What I had was too soft and allowed the kevlar to run away into the wood under the knife's pressure.

Bill
 
My only experience cutting kevlar was years ago. A fellow I shot IHMSA with and I cut some level IIIA ballistic panels and sewed them into special carriers for use as leg guards when shooting in the creedmore position. We used a band saw, and it worked fabulously, however, I don't think that would work on something as flimsy as kevlar fabric. The best I can come up with is serrated shears .
Wave
 
Bill1170 said:
Anybody here have experience cutting this stuff? What works for you?

Bill
Click to expand...

I have worked with Kevlar fabric. We used ceramic bladed scissors to cut the stuff. High quality cutting shears also work, but not for long.

There's a reason they make bullet proof vests from the stuff.

Edited to add:
These are what you need in order to cut Kevlar, anything else is the wrong tool for the job:
http://store.cablesplususa.com/45483a.html
http://www.surveillance-video.com/10530.html?productid=10530&channelid=NEXTA
 
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I make Kevlar and Dynemma webbing, and have found any sharp knife will cut it with little problem, though it will dull the blade very quickly. I usually use a SAK and it zips through it fine. My co-workers use scissors and they can have problems with thick webbing and sometimes ask me to cut it for them with my knife.
 
knarfeng said:
I have worked with Kevlar fabric. We used ceramic bladed scissors to cut the stuff. High quality cutting shears also work, but not for long.

There's a reason they make bullet proof vests from the stuff.

Edited to add:
These are what you need in order to cut Kevlar, anything else is the wrong tool for the job:
http://store.cablesplususa.com/45483a.html
http://www.surveillance-video.com/10530.html?productid=10530&channelid=NEXTA
Click to expand...
Knarfeng,

Thank you very much for the links. These are what I was looking for. I am thinking the pair with the bigger finger holes is the one to get.

Roger999,

Yes, any more knife work gets a sacrificial surface on the bench. I think a scrap of maple would be better than standard plywood, because the problem I had was the blade sinking too far into a softer wood, so it failed to develop the pressure opposite the edge to effect the cut. Maybe baltic birch ply would work for me. I am liking shears better for this job in any case.

Bill
 
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