Heat shrink question?

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

RocketManDan

Well-Known Member
Joined
May 19, 2011
Messages
1,817
Reaction score
4
I know some people like to tie a knot to fasten their Kevlar shock cord and some go one step more and add a couple drops of glue to the knot. I was wondering would it hurt to use heat shrink over the knot? I doubt it would increase the strength at all, but I just think it would look cleaner than just having a knot there.

What's everyone's feed back on this?
 
Interesting idea. I seem to be wrong a lot, but heat shrink has no elasticity, so I am not sure how well it would grab. It seems like it would look nice, but not function for an extended period of time.
I used it on a small flashlight body once to make it slightly larger for my big fat mitts to grab. After a while it became slack on the light, though that may have been caused by the oils in the machinery I worked on.
 
I have been doing just that for some time now. Not only does it look good, it also reduces the chance of a snag or tangle at the knot. I used to use Testor's plastic glue on kevlar knots, but don't anymore because you can't untie them, and I'm always changing something on my recovery gear. One of the nice things about kevlar is that it is so easy to untie, even after a hard deployment of your chute.
 
If there is ever a question in regards to being anal retentive, just shoot Wayne a p.m. Chances are he's already done it. His stuff is ridiculously clean.
 
Wayne

Does the heat shrink itself jeopardize the strength of the Kevlar knot? I'm going to start doing on all my future builds...

Can you post some pictures?
 
It's standard on fruity chutes and I've had kids use it for TARC. Glue, particularly CA, will harden Kevlar such that it is weaker than if left flexible but the heat shrink will keep knots from slipping without doing that and eliminates loose ends.
 
If there is ever a question in regards to being anal retentive, just shoot Wayne a p.m. Chances are he's already done it. His stuff is ridiculously clean.

HEY! I resemble that remark!
And what's up with you Tom? Nothing on the forum for months, doesn't show up at the club launches, and first thing I hear is a comment like that.... :confused:
But I digress, back on topic here. The heat shrink doesn't seem to have any effect on the knot as far as I can tell, and with care, you can cut it off without damage to the cord most of the time. Thanks to another forum member I have started using the "Non-slip Mono knot" that I had forgot about from my fishing days, here is a great site that will help you learn it too:
https://www.animatedknots.com/nonsl...ge=LogoGrog.jpg&Website=www.animatedknots.com
I like this knot because it distributes the load over a larger area, and is easy to untie also.
 
HEY! I resemble that remark!
And what's up with you Tom? Nothing on the forum for months, doesn't show up at the club launches, and first thing I hear is a comment like that.... :confused:
But I digress, back on topic here. The heat shrink doesn't seem to have any effect on the knot as far as I can tell, and with care, you can cut it off without damage to the cord most of the time. Thanks to another forum member I have started using the "Non-slip Mono knot" that I had forgot about from my fishing days, here is a great site that will help you learn it too:
https://www.animatedknots.com/nonsl...ge=LogoGrog.jpg&Website=www.animatedknots.com
I like this knot because it distributes the load over a larger area, and is easy to untie also.


I book marked the page..Thank You!
 
Here are some pic's of the different recovery systems with heat shrink:
016-1.jpg

012-1.jpg

010-1.jpg

I recently started using 16mm split rings to attach my chutes to the loop in the kevlar, only time will tell how they will hold up to a fast deployment, but I'm sure there will be one eventually. I added a small piece of heat shrink to that loop to make it easier to slip the split ring on. On my HPR Nuke Pro Max I use a quick link, but haven't found any of those small enough for my LPR/MPR rockets.
 
Wayne I like the split ring idea. Looks like it would work well on smaller rockets. I also used some heat shrink on some Kevlar I had laying around my shop. It works fine. I'm going to start using it on all my builds for now on. Gives it a clean look.
 
Back
Top