Aug 19, 2010 at 10:29 am #1262401
Hi! I'm thinking about getting some kevlar to reinforce the bottom of a backpack and put some large crampon patches on two pairs of trousers.
Never worked with kevlar before so would be great if anyone out there could offer some advice.
First, I have found three different kevlar fabrics here in europe, two that are supposed to be 100% and one that's 23%.
Which one do you think would work best? No doubt about it, the 100% is the thoughest, but do I need it?
Is it possible to sew it with a normal sewing machine or do I need to have a industrial one? What kind of braid and needle should I have?
Or could I glue it? I'm gonna attach it to both a superstretchy softshell(Shoeller dryskin extreme), 3-layer Gore-tex proshell and some ordinary nylon fabric used on a backpack I got.
And lastly, do I really need some super expensive scissors? Wouldn't it be possible to use some cheap gardening scissor?
Edvin MellergårdAug 19, 2010 at 10:40 am #1638694
"And lastly, do I really need some super expensive scissors? Wouldn't it be possible to use some cheap gardening scissor?"
I tried to use generic scissors on some course 100% kevlar used in canoe repairs. I got nowhere! Not 5mm. A steel wheel cutter did nothing, just folded the fabric. The $35 scissors, supposedly for kevlar, were done after about 2 meters.
So, YMMV, but this is one place where a specific tool is worth the $$. Get the fabric, go to the shop, and see if what they have will actually do the job. My local shopkeeper was shocked at how ineffective her "excellent" scissors were.
Or, have your supplier cut the pieces you need.Aug 19, 2010 at 11:06 am #1638700
@carlbeckerLocale: Northern Virginia
Years ago I made a composite canoe using fiberglass and kevlar. I purchased special sissors to cut the kevlar and they worked great. Do not expose kevlar to sunlight directly. You should have no problems getting a needle through the weave for sewing but I would pick a different fabric for reinforcing.Aug 19, 2010 at 11:26 am #1638709
Ok, guess I would have spend some extra money on the scissors then :(
Why would you choose a different material for reinforcing? This won't be for a pair of super lightweight trousers, weight is definately an issue but what I want to do is to reinforce the lower section with the kevlar patches and also some hooks at the front for the laces on my boots and a strap under the boots so I can get rid of my gaiters, sould be able to save quite alot of weight in total.Aug 19, 2010 at 12:03 pm #1638729
is the a reason standard packcloth or dyneema grid stop wouldn't work in those applications?
-TimAug 19, 2010 at 12:18 pm #1638738
@owareLocale: Steptoe Butte
Spectra or Dynema would melt and you could cut it with a cheap
soldering iron. Just as tough. Lighter too.Aug 19, 2010 at 2:30 pm #1638787
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
You can cut Kevlar with carbide (or ceramic) scissors. But a soldering iron is better for all those performance fabrics.
But Kevlar is a bad choice for outdoors use as it is quite UV sensitive. Go with David O's advice.
CheersAug 19, 2010 at 3:03 pm #1638798
@woodenwizardLocale: Greater Mt Tabor
Sorta off topic
So I guess Kevlar canoes would be a tremendous waste of money? Or do they coat them in somethingAug 19, 2010 at 3:14 pm #1638803
Very Off Topic…
Cuben could also be seen as a tremendous waste of money . . .
(BTW, I have owned 2 kevlar canoes. Neither died from UV exposure.)Aug 19, 2010 at 3:47 pm #1638812
@acrosomeLocale: Back in the Front Range
I think kevlar canoes are coated in epoxy, just like fiberglass ones. I mean, obviously- unless you're doing skin-on-frame how else do you make a boat out of CLOTH?Aug 19, 2010 at 6:03 pm #1638848
@vickrhinesLocale: Central Texas
I don't recommend using Kevlar at all.
1) Unless you use DuPont "Nomex" you are in for a world of frustration with Kevlar. Even Nomex is a bear to cut. Kevlar also absorbs lots of water, sunlight wrecks it and it deteriorates quickly when exposed to the elements, including water. It is significantly weaker when full of water.
2) Consider Thruhiker's Spectra grid or just plain Cordura. Even 600 denier Cordura will outperform Kevlar when all things are considered – including the factors many others have noted.Aug 19, 2010 at 10:24 pm #1638907
What about this stuff?
It looks a lot like thru-hiker's Dyneema X, but at nearly twice the weight and MUCH less expensive.
I'm tempted to order it myself based solely on the price.Aug 19, 2010 at 10:44 pm #1638909
Even the Dyneema X Gridstop that thru-hiker sells (which is 210D and about half as light as the ebay stuff), is a PITA to cut. It completely dulled my Ginghers. I recommend buying some cheap-o titanium coated Mundials to work with the stuff, or just use a utility knife on a surface that you don't mind scarring.. The spectra is rough on any blade.Aug 20, 2010 at 5:22 am #1638930
Stick with spectra. Tough enough for Ursacks.Aug 20, 2010 at 10:53 am #1639009
@carlbeckerLocale: Northern Virginia
It has been a long time since I made my solo white water canoe. When you use composites to build a canoe you do reseach to find what types of materials and weaves work best within your budget and how each fabric works with others as well as which specific resins. Kevlar is very light, light sensitive with great tension strength. If placed in the proper layer or layers of a composite it has good advantage as well as not so good properties. Other fabrics are also used like S-glass and E-glass types of fiberglass, nylon and now others. Generally speaking the best canoe (weight to strength) will not be made from one type of fabric but many laid in a specific order. If kevlar is used for the inside last layer then the resin is usually pigmented if the boat is to be kept for any length of time. Kevlar does not tolerate push-pull (compression then tension repeatedly ) motion well and will fail. It does best in tension and seems to have high abrasion resistance. I don't know the best fabric for your application but IMHO it is not kevlar. Define the properties you want, strenght, UV properties, abrasion properties, weigth, etc then find or ask which fabric most closely matches your needs. I am sure there will be some compromise somewhere, there always is.Aug 20, 2010 at 2:47 pm #1639068
I have some familiarity with those materials and others, but I think kevlar is one of the best choices since he must be looking for an extremely tough material if he's asking for kevlar. Yes, UV does weaken it and it does take up water, but is that really an issue? The first link he provided had two types of kevlar that had a UV resistant coating. Without looking into the specifics of that coating, I bet it would do a pretty good job of deflecting water as well.
Off topic now… About that canoe. Heat causes each material expands and contracts at different rates. Have you seen that cause problems in canoes as far as you've seen?Aug 23, 2010 at 1:43 am #1639698
Thanks for all the input, unfortunately I don't think even really thick cordura will do the job good enough, that's why I wanna go with kevlar. The main problem with snagging a crampon isn't that i rip my clothes, it's that I'm very likely to fall.
So the main feature I'm looking at is actually puncture resistance.
Good thing about the UV and water issue, one of the fabrics I was looking at didn't have any coating at all, so that one is a no go. I have ordered samples from the other two qualities to check them out, hopefully I'll be able to swe them with my normal sewing machine, otherwise I guess I have to let a professional do it.Aug 23, 2010 at 2:23 am #1639703
In that case, do you have a way to make sure your trousers are tight when you are using your crampons? If not, I'm sure the crampons will still snag. I'm planning on doing something like that to make gaiters that replace the bottom half of my convertible pants when I'm on icy snow. You may want to consider putting resin on that kevlar patch to make it stiff enough that the crampons can't snag on it.Aug 23, 2010 at 2:47 am #1639705
yes, I've been thinking about that too, the goretex pants I want to add the kevlar too is definately too wide so I'm gonna sew something to make them tighter, the softshell pants is already quite tight since I've already cut of quite alot of material from them.
Any idea what I could add to make the kevlar stiffer? Thinking about epoxi or polyester, the same thing that's used for kayaks or boats, it's a quite flexible but not "foldable" without breaking the plastic if you understand what I mean.Aug 23, 2010 at 3:18 am #1639706
The best bet for choosing an epoxy or resin is to contact a company that deals with that sells various types. Aircraft Spruce might be a good place to start. Polyester sounds right though. It's been forever since I read my composites books, but I believe that's more malleable and can be reshaped with heat.
If you're going to make it stiff, look into the carbon fiber/kevlar blends. I have that on my motorcycle boots. I don't know if that's the best way, but it's something to consider. It'll add an even more unique look too.
Just don't ask me how you'll get it to stick to your pants. However they do it in motorcycle gear is probably the best way. If I crash hard wearing my gear with composite patches on my motorcycle, hopefully I'll survive well enough to let you know.Aug 23, 2010 at 3:43 am #1639707
Polyester exists as both a thermoplastic and a thermoset, the one commonly used in composite materials is a thermoset so it isn't heat remoldable. Getting it to "stick" is quite easy, when you buy it, it's a liquid, then you add a catalyst which makes the polyester cure, so just spray or paint the polyester on the fabric and once it cures it should be stiff.Aug 23, 2010 at 7:36 am #1639734
@owareLocale: Steptoe Butte
Make some patches out of kydex? You can sew through thin
bits of it.Aug 23, 2010 at 9:05 am #1639752
@vickrhinesLocale: Central Texas
Consider using ballistic nylon. If you need a stiffiner, put semi-rigid plastic sheet under it. I have worked with Kevlar in boat making and even for knife sheaths. I would not consider using Kevlar – or any other fiber – in conjunction with polyester or epoxy resin. The base fabric will fatigue and fail around the area saturated with resin.
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