# Kevlar

### Help Support The Rocketry Forum:

#### GNaroz

##### Member
I have always built Estes kits with the Tri Fold Shock cords mounts. After building a few Quest kits, I really like the Kelvar anchored to the Engine Mount. My question is where is the best and most cost effective place to get the Kevlar cords so I can convert all my new Estes builds to the Kevlar mount? I have seen a bunch on Ebay but I an not sure what ones would work the best. Where do you guys get them from?

This is strickly for LPR stuff, nothing more...

#### Pem Tech

##### Well-Known Member

Or you can purchase small quanteties from such nice folks as
http://www.pratthobbies.com/
or us
Pem-Tech (even though it isn't listed on the website yet)

8 oz, KEVLAR size 415
Price - 15 cents per foot

We use 60" of this on all of your LPR kits and even use it for shockcord anchors on our Bucky Jones and M2 Mid Power kits. It is good stuff.

And there are other great folks that sell KEVLAR thread but I am having troubles with boomarks at the moment.

Last edited:

#### mjennings

##### Well-Known Member
I got some from FlisKits (www.fliskits.com), that way you can get some Kevlar and a couple Flis rockets too!

#### jj94

##### Well-Known Member
I get the thicker stuff for MPR at Commonwealth. I think its anywhere from 10-25 cents per foot. I can't remember. I get my kevlar thread for LPR from everywhere.

#### o1d_dude

##### 'I battle gravity'
TRF Supporter
Try BRSHobbies.com for the 100 lb Kevlar in 24' lengths at $2.99 each. Shipping is extra of course.$4.95 flat rate on orders under \$75 and free after that.

#### Pat_B

##### Well-Known Member
The Thread Exchange has really good pricing. A lot of Kevlar has a particular twist to it (I can't remember if it's left of right) because it is made to go through a sewing machine. The Kevlar with the opposite twist is not suitable for sewing so it's much cheaper. Check out the Thread Exchange website for details and you can find tech info on the details as to which is the cheapest for rocketry needs.

#### Commonwealth.Net

##### Well-Known Member
The Thread Exchange is a good place for Kevlar STRING / Thread.
It has a draw back, it comes apart after several uses!
It has a breaking strenght of 40 to 100 pounds.

SOULTION: Braided Tubular Kelvar rated at 200 pounds.
2 to 5 times as strong, wont come apart. A good to 1400
degrees.

Cost about the same a Kevlar String!!!

See www.commonwealth.net
See the recovery section for this and MORE Kevlar Products.

#### Pem Tech

##### Well-Known Member
The Thread Exchange is a good place for Kevlar STRING / Thread.
It has a draw back, it comes apart after several uses!
It has a breaking strenght of 40 to 100 pounds.

SOULTION: Braided Tubular Kelvar rated at 200 pounds.
2 to 5 times as strong, wont come apart. A good to 1400
degrees.

Cost about the same a Kevlar String!!!

See www.commonwealth.net
See the recovery section for this and MORE Kevlar Products.
Hmmmmmm...
Since I am not sure which Kevlar string/thread you are referring to I'll just state that I have yet to replace any 8 oz, KEVLAR size 415 shock cord used in my personal LPR and MPR builds, all of which have numerous flights, or heard any complaints from customers. The only time I have seen it fail was after a motor CATO that charred the interior of the rocket. In that case there was not enough rocket left to replace the shock cord. Got a good shot of that one too, very exciting.

#### Micromeister

##### Micro Craftman/ClusterNut
TRF Supporter
Personally I've been using a motor mount shockcord anchor system since the late 70's.
even on minimum diameter models (that use a motor block) and I've retro-fitted just about every model I've built in my new fleet as well.

I purchase most of my Kevlar from the thread exchange. and some braided kevlar from Pratt Hobbies.
below is a little thread size chart that may take a little of the confusion of thread size, break strength and diameter out of the picture.
Hope this helps

#### Pem Tech

##### Well-Known Member
Thanks Micro, that makes identification and comparison much easier.

ANd by the way, is there anything you don't have a picture of on a Blue-green background?

#### GNaroz

##### Member
Great info, Thank you to all!!

#### MarkII

##### Well-Known Member
The microbraid Kevlar from Pratt Hobbies is excellent quality, astoundingly strong and durable. It rolls up easily so it is easy to stuff into a small diameter tube. Because it is braided, it won't unravel.

I have also used plenty of Kevlar twine from BRS Hobbies, and I have been quite satisfied with it. Their twine is twisted, though, rather than braided.

I obtain my very lightweight (28 lb.) Kevlar from FlisKits. It resembles very thin thread and appears to be a monofilament, but in fact it is made from multiple hair-thin strands.

I have never found any Kevlar (aramid fiber cord or thread) in retail stores; the only places I have seen it were through online hobby and craft supplies vendors and on ebay.

As an alternative to Kevlar, I have also used 49-strand or 19-strand nylon coated stainless steel beading cord on occasion. You can find it at crafts stores like Michael's and Joanne's, and sometimes in the crafts section at Walmart. It is very fine (0.012", 0.015" and 0.018" diameters are available) and is very flexible. The 19-strand is marginally less flexible (the higher the strand count, the more flexible the cord) but it also works well as a shock cord or cord leash. Either kind is very fine in diameter, extremely smooth in finish, virtually kink-proof and extremely resistant to tangling. Avoid the more common (and less expensive) 7-strand steel cord; it is much stiffer and harder to work with. And by all means stay away from the type of metal beading cord called "tiger tail." The stuff is about as easy to work with as picture hanging wire. A major brand is Beadalon. The 0.012" 19 strand has a breaking strength of 12 lbs. and is hair-thin; it works very well in Micromaxx models. I prefer using it over very lightweight Kevlar for such models because of its smooth texture and resistance to tangling. The 0.015" 49-strand has a rated break strength of 20 lbs. and works fine in most small to medium-sized LPR models.

Metal beading cord is more expensive per foot than most Kevlar that you can find (at least the stuff at Michael's is - 0.45 per foot although you can probably find better prices for it online), but unlike Kevlar, it is something that you can run to the store and get if you need it right away. You can knot it, but a better, cleaner way to attach anything to it is to create a loop it it and then join the tag end to the line with a crimp bead. Braided stainless steel beading cord resembles bulk fishing leader, but it is finer in diameter, smoother in finish and has a softer flex. And you can find it at more retailers. The stuff is even more fireproof than Kevlar, too; in fact, nothing short of a severe cato will melt it, and it will hold up fine after exposure to many, many ejection charges.

MarkII

Last edited:

#### Micromeister

##### Micro Craftman/ClusterNut
TRF Supporter
Mark is correct:
Stainless beading wire or small diameter stainless aircraft cable make pretty much indestructable motor mount wrapping Micro to MPR Shockcord anchors.
Coupled with Kevlar or Kevlar/elastic shockcords our models now rarely need to have shockcords changed or suffer from seperations in flight.

Another option is braided stainless fishing leaders which come already looped and some with snapswivels.

here are a few of the options photos.
I didn't put these options up earlier as you weren't asking about anchoring systems but Kevlar purchase sources. Didn't want to cause to much information overload