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Old Oct 17, 2011, 07:33 AM
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dydx's Avatar
Brisbane, Australia
Joined Mar 2006
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Cutting Kevlar

Hi All

I was just wondering what folks out there use to cut kevlar? I've never worked with it before and don't seem to have anything in my shop that can give me clean edges on the 75gm cloth that I'm using for doublers.

Do I need a pair of those special serrated shears?

Cheers
Pete
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Old Oct 17, 2011, 07:35 AM
Composites Kid
Alex.Schweig's Avatar
Lima, Peru
Joined Jul 2008
3,122 Posts
Give a good pair of Fiskars the Samotage treatment and youŽll be cutting golden fabric in no time!

http://www.rcgroups.com/forums/showthread.php?t=657516
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Old Oct 17, 2011, 07:58 AM
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Brisbane, Australia
Joined Mar 2006
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Thanks Alex, Samotage, I'll give it a go
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Old Oct 17, 2011, 08:16 AM
Red Merle ALES
Curtis Suter's Avatar
United States, Mt, Helena
Joined Apr 2002
5,794 Posts
I use some scissors from the Dollar Store. They are used for cutting leather, they look something like this:
http://www.amazon.com/gp/product/B00...6JQX6XXTS1JVJ7

It's all in the angles of the blades, Phil Barnes has solved this inexpensively also:
http://www.rcgroups.com/forums/showthread.php?t=795224

Curtis
Montana
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Old Oct 17, 2011, 09:38 AM
Live and let Fly !
Lawrence B's Avatar
Mill Hill - London
Joined Aug 2009
107 Posts
+ One for the re edged scissors. I dont have a sander, i re edged mine on an off hand grinder.


LB
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Old Oct 17, 2011, 10:24 AM
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Blackrat's Avatar
South Africa, WC, Knysna
Joined May 2006
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the serrated scissors are great, but they done last long .. i tried to keep mine only for kevlar but when you see how great they cut everything else you just cant help yourself *shrug*

so now i grind an old pair and they work great again ...
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Old Oct 17, 2011, 10:57 AM
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Joined Dec 2006
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grinder vs sander

i find that using a (stone) grinder only makes the edge dull and rounded. for a while, i could not figure out why this technique was not working. then, i tried using a sander and it worked really well.
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Old Oct 17, 2011, 11:41 AM
G_T
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Joined Apr 2009
5,884 Posts
Key IMHO is you don't really want a smooth edge. You want one with tooth so the fabric cannot try to slide down the blades. You also want a right angle edge on the blades because the action is not a cutting action but a shearing action.

Gerald

PS - By "tooth" I mean coarse sanded so the sanding striations are clearly visible. Smooth is no good.
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Old Oct 17, 2011, 06:50 PM
Registered User
Germantown, Maryland
Joined Apr 2004
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Ditto what GT said. Think in terms of something like 60 grit.
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Old Oct 18, 2011, 01:22 PM
Chuck 'Em and Chase 'Em
Fly2High's Avatar
United States, NY, Plainview
Joined Aug 2005
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I purchased the fiskars with the serrated edge for Kevlar and I hate to say it but they do not cut light kevlar as easily as Phil's modified scissors do. Plus they are cheaper and when they do ot cut, a quick hit with sandpaper, file or grinder and they are as good as new. the serrated do cut the heavier stuff but then again so do Phil's.

Thanks Phil for disclosing this idea......
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Old Oct 19, 2011, 05:18 AM
Launchpad McQuack
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Netherlands, Moordrecht
Joined Sep 2004
1,132 Posts
Little trick for cutting small parts:

Mark your shape on the Kevlar, apply some CA on the cutting line, leave to dry, then cut the Kevlar with normal scissors.

Only works if the Kevlar is applied on single curvature surfaces, since the fibers are stuck.
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Old Oct 19, 2011, 05:47 AM
chetosmachine's Avatar
Madrid, Spain
Joined Sep 2004
1,105 Posts
Contrary to what everyone uses, I have a very expensive (120eur) scissors that cuts everything, from 25g glass to 200g kevlar without any hassle.
I had a pair of modified scissors, but they needed re-sharpeneds every few cuts, I guess they were not heavy duty.
My expensive scissors only see dry fabrics; to cut wet fabrics, I have a pair of curved scissors that also are expensive (60eur) but they cut everything and are good for working with molds.
I have never regreted to buy the expensive tools, since cheaper one did not show reliable to me (they would get dull mostly when everything was in the mold and I really needed to cut the stupid kevlar).
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Old Oct 19, 2011, 07:11 AM
Launchpad McQuack
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Netherlands, Moordrecht
Joined Sep 2004
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Probably Robusto Proton scissors?

http://www.robuso.com/shop/details2....000&CatID=1010
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Old Oct 19, 2011, 08:07 AM
Chuck 'Em and Chase 'Em
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United States, NY, Plainview
Joined Aug 2005
8,120 Posts
Are both blades micro serrated or just one on your scissors?

Who sells the ones you suggest?

I am not sure how cost effective those are but I wonder if using a coarser file/sandpaper/grinder would yield longer lasting results?

I think it is the biting ability of the roughening up or the serrations that allows either set to work.
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Old Oct 19, 2011, 10:49 AM
Just fly it!
wyowindworks's Avatar
Cody, WY
Joined Nov 2007
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Quote:
Originally Posted by chetosmachine View Post
Contrary to what everyone uses, I have a very expensive (120eur) scissors that cuts everything, from 25g glass to 200g kevlar without any hassle.
I had a pair of modified scissors, but they needed re-sharpeneds every few cuts, I guess they were not heavy duty.
My expensive scissors only see dry fabrics; to cut wet fabrics, I have a pair of curved scissors that also are expensive (60eur) but they cut everything and are good for working with molds.
I have never regreted to buy the expensive tools, since cheaper one did not show reliable to me (they would get dull mostly when everything was in the mold and I really needed to cut the stupid kevlar).
I agree. I've got a pair of ceramic edged scissors that have lasted 3 years without the need to be resharpened.

I also agree that the Fiskers serrated edge scissors are a total waste of money.
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