Sharpening Kevlar Scissors? - RC Groups
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Jan 02, 2008, 09:21 PM
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wyowindworks's Avatar
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Sharpening Kevlar Scissors?


Has anybody ever tried to sharpen their kevlar scissors? How did it work? What was your technique?

After cutting out pieces for 30 fuses, mine are dead.
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Jan 02, 2008, 09:28 PM
Jesper Frickmann
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I use Phil Barnes' method. Take a regular pair of scissors, sand at a 90 degree angle with disk sander or sanding block. No need for special scissors.

Jesper
Jan 02, 2008, 09:48 PM
Registered User
I just make a few passes with a relatively coarse stone and mine are back in business.
Jan 02, 2008, 10:16 PM
Registered User
Nothing special about kevlar scissors except they are rubbish for cutting anything else.

Get 2 bits of angle iron. Put them together so 2 faces are together and drill a hole so you can put a bolt through both bits at one end (Kind of scissor like). Polish both faces so they rub nice and close and you can make longer cuts in kevlar cloth.
Jan 02, 2008, 10:25 PM
Just fly it!
wyowindworks's Avatar
Quote:
Originally Posted by jfrickmann
I use Phil Barnes' method. Take a regular pair of scissors, sand at a 90 degree angle with disk sander or sanding block. No need for special scissors.

Jesper
Yep....I tried the Phil Barnes method. It is nothing compared to a good pair of kevlar scissors....IMHO. The PB method worked o.k. for me on 1.7 oz, but totally blew on 5 oz. I absolutely HATE it when the scissors bend the kevlar rather than cut it.

Quote:
Nothing special about kevlar scissors except they are rubbish for cutting anything else.

Get 2 bits of angle iron. Put them together so 2 faces are together and drill a hole so you can put a bolt through both bits at one end (Kind of scissor like). Polish both faces so they rub nice and close and you can make longer cuts in kevlar cloth.
Have any pictures? I'd like to see that one in action.
Jan 02, 2008, 11:22 PM
Registered User
Quote:
Originally Posted by wyowindworks
Yep....I tried the Phil Barnes method. It is nothing compared to a good pair of kevlar scissors....IMHO. The PB method worked o.k. for me on 1.7 oz, but totally blew on 5 oz.
You would want a fairly decent quality stainless steel scissors with a tight hinge for cutting 5.0oz Kevlar but you still don't need to buy expensive scissors that are specially made for cutting Kevlar. The disk sander modified regular scissor still work better.

To "sharpen" them after they get "dull", you just run them across the disk sander again, or an upright 1" wide belt sander, or whatever. You need to buy a new pair of $17.00 scissors after you've "sharpened" them enough times that the blade gets real small

All of the scissors in my shop are modified for cutting Kevlar and I use them for cutting anything that comes into my hand that is in need of cutting.
Jan 02, 2008, 11:33 PM
working to the closest cm
jirvin_4505's Avatar
I grab any old pair of scissors abandoned and run them through the grinder/ sander as per phil works on different weights of cloth. I resharpen them before cutting (takes 1 minute) and change them over as soon as they start to baulk at the cloth.

Don't try this at home without parental supervision........
Many years ago in a far off country (Australia) my friend Walter cut multiple layers of 6oz kevlar at once.


He put a industrial fabric cutting wheel (Like a large olfa rotary cutter 4-6") into an angle grinder. The multiple layers of thick kevlar were place onto a layer of sacrificial foam. He then cut through the multiple layers of kevlar into the foam following a pattern drawn onto the cloth.

have fun Jeff
Jan 02, 2008, 11:51 PM
Just fly it!
wyowindworks's Avatar
O.K. - I can take a hint....even by Phil Barnes himself . I will give it another go tomorrow morning. Do you do both blades at 90 deg or just one?

Adam
Jan 03, 2008, 01:33 AM
working to the closest cm
jirvin_4505's Avatar

cutting kevlar with dremel


I get distracted!! Too wet and windy to fly or paint my molds....

Thought I would do a bit of messin around in the shed

I repeat don't do this without parental supervision...
https://www.rcgroups.com/forums/showthread.php?t=795366

enjoy..
Jeff
Jan 03, 2008, 01:40 AM
Registered User
As simple as some make look, it aint that simple. There are a whole lot of variables, just think about it and start adding the variables up. Every single thing is variable! You are going to need to experiment and find what will work best for you. I have tried everything, files, sandpaper, disc sander, diamond stone, blah blah blah. I have to sharpen more often than I would like which is almost never!

One of my best kevlar scissors is a Mundial micro serrated (#1890) from the local fabric store. I have had it for a good 10 years and it still cuts great. About $20. I don't do production work and don't cut anything other than kevlar with it but by now I know I have got my money's worth. And I have never ever sharpened it! Don't tinker with something that is not broken!

Is the medium diamond stone from Harbor Freight = to your own local source for medium? Is Phill Barnes sanding disc sourced from Germany or the US? How much pressure is he applying? Is he on steroids or HGH? if so, who is his favorite pharmocist? Is his favorite grit new or worn out, and what is his favorite RPM?

See what I am saying? Lots of variables. Experiment.
Jan 03, 2008, 07:38 AM
Registered User
Quote:
Originally Posted by wyowindworks
... Do you do both blades at 90 deg or just one?
Both
Jan 03, 2008, 07:56 AM
Registered User
I prefer to use relatively coarse grinding disk to create kind of 'micro-serrations' on the edge, this keeps the fabric from slipping along the blade. Grinding wheel direction of rotation such that burr is created on the inner edges of blades, then open and close the scissors couple of times to bed in the blades - gives a nice 'kerrunch' sound/feel. Don't let the blades become dull in the first place, it is much less work to sharpen them lightly but often.
Jan 03, 2008, 08:12 AM
Chuck 'Em and Chase 'Em
Fly2High's Avatar
First off Phil's method is the best. I have used a set of Fiskars sanded edge scissors on 1, 1.7 and 3 and 6 oz kevlar. No problem. I did try a set of serrated scissors from Home Depot. They are the fiskars titanium ones. Works well on the heavier kevlar but not good on the lighter stuff.

I think Phil's method puts a sort of serrated edge (edge has micro pits/chunks taken out of the edge) and it is these 'serrations' that hold the fabric while the blade cuts. Otherwise, the fabric wants to slide or fold in the teeth.

I was wondering, When they makes things from ripstop nylon, they use a hot knife - looks like a merging of an Exacto and a soldering iron. It cuts inpart by melting the cloth. Works great to prevent the edges from fraying.

Has anyone tried using a hotknife to cut kevlar?

Frank
Jan 03, 2008, 08:59 AM
Jesper Frickmann
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Given that Aramid/Kevlar is used for fire-protective clothing and asbestos replacement, I do not think the hot knife would work.

Jesper
Jan 03, 2008, 09:04 AM
I DS slower than I build!
Cory's Avatar
I doubt a hot knife would work. Kevlar handles pretty high temps. It's commonly used as the outer layer of firefighting clothing. It chars instead of melting like nylon does.


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