Not Going to Run Out of 1/8” Flat Elastic Shock Cord Now

[brockrwood]

I was tired of never being able to lay my hands on a sufficient length 1/8” flat elastic shock cord when I needed it.

So I bought a 170 yard spool of it for $10.

The excess elastic shock cord will be distributed as part of my estate.

 

[cls]

Seems like a good idea. But, reminds me of when I bought a big can of SIG contest rubber. At the time we were flying indoors rubber band powered microlight airplanes. Never got through even a quarter of the rubber! It all rotted.

I think elastic lasts more than a few years.

 

[Hobie1dog]

I usually buy the wider stuff. I only see it in small packages. Good find.

 

[Bill S]

That ought to hold you for a while.

 

[rharshberger]

I wont every run out either...I quite using elastic years ago in favor of kevlar with lightly taped z-folds in LPR and regular taped z-folds in MPR and HPR.

 

[brockrwood]

I wont every run out either...I quite using elastic years ago in favor of kevlar with lightly taped z-folds in LPR and regular taped z-folds in MPR and HPR.

How do you attach the kevlar in an Estes kit that uses the tri-fold piece of paper shock cord mount? I am always afraid it will just cut right through the shock cord mount. If I can modify the kit to use a Quest style shock cord mount, I use kevlar. If I am building it stock, I replace the rubber shock cord with elastic, just because I can lengthen it a bit and it seems to last longer.

 

[rharshberger]

How do you attach the kevlar in an Estes kit that uses the tri-fold piece of paper shock cord mount? I am always afraid it will just cut right through the shock cord mount. If I can modify the kit to use a Quest style shock cord mount, I use kevlar. If I am building it stock, I replace the rubber shock cord with elastic, just because I can lengthen it a bit and it seems to last longer.

Not to many Estes kits made that I don't ditch the trifold mount too, there are other ways to mount shock cords. The larger the diameter the tubes the more options I have.

 

[OzHybrid]

I was tired of never being able to lay my hands on a sufficient length 1/8” flat elastic shock cord when I needed it.

So I bought a 170 yard spool of it for $10.

The excess elastic shock cord will be distributed as part of my estate.

View attachment 600330

Get some zip-loc bags and gift small bags to the other members of your club. You'll never use it unless you start an elastic cord macrame class.
When you need some epoxy in a hurry, you'll have some credit in the bank.

 

[Back_at_it]

I was tired of never being able to lay my hands on a sufficient length 1/8” flat elastic shock cord when I needed it.

So I bought a 170 yard spool of it for $10.

The excess elastic shock cord will be distributed as part of my estate.

View attachment 600330

I buy the same thing off amazon in various sizes. You'd be shocked how fast you go through it.

 

[OzHybrid]

I buy the same thing off amazon in various sizes. You'd be shocked how fast you go through it.

Elastic macrame classes?

 

[cwbullet]

How do you attach the kevlar in an Estes kit that uses the tri-fold piece of paper shock cord mount? I am always afraid it will just cut right through the shock cord mount. If I can modify the kit to use a Quest style shock cord mount, I use kevlar. If I am building it stock, I replace the rubber shock cord with elastic, just because I can lengthen it a bit and it seems to last longer.

I usually just anchor it to the motor tube.

 

[Back_at_it]

How do you attach the kevlar in an Estes kit that uses the tri-fold piece of paper shock cord mount? I am always afraid it will just cut right through the shock cord mount. If I can modify the kit to use a Quest style shock cord mount, I use kevlar. If I am building it stock, I replace the rubber shock cord with elastic, just because I can lengthen it a bit and it seems to last longer.

Typically attach to the motor tube or upper centering ring during new builds. When replacing old shock cords, I've used the Estes tri-fold mount without fail with various sizes of Kevlar.

 

[brockrwood]

I buy the same thing off amazon in various sizes. You'd be shocked how fast you go through it.

Yep. Amazon. 1/8" 3mm White Braided Elastic... https://www.amazon.com/dp/B0BBW3DVTQ?ref=ppx_pop_mob_ap_share

 

[Tractionengines]

Long drill bit. Drill up from motor mount, and glue in a plastic coffee stirrer. Loop kevlar over the MMT and up thru stirrer tube.

Makes inspection and future replacement easy too.

 

[cwbullet]

Yep. Amazon. 1/8" 3mm White Braided Elastic... https://www.amazon.com/dp/B0BBW3DVTQ?ref=ppx_pop_mob_ap_share

The best part is that they have both 1/8" and 1/4" at a relatively good price. They are nominal sizes with 3 and 6 mm.

 

[brockrwood]

Long drill bit. Drill up from motor mount, and glue in a plastic coffee stirrer. Loop kevlar over the MMT and up thru stirrer tube.

Makes inspection and future replacement easy too.

Plastic coffee stirrer! Cool trick!

 

[SolarYellow]

Amazon has cotton sheathed elastic in 1/4 and 3/8 in bulk. https://www.amazon.com/gp/product/B004KVTS44/

I haven't found it in 1/8 anywhere.

This post discusses why cotton and links to a source with neoprene elastomer instead of the latex used by Dritz in the Amazon link above.
https://www.rocketryforum.com/threads/sources-for-1-8-wide-elastic-shock-cord.177868/#post-2391597

 

[mh9162013]

How do you attach the kevlar in an Estes kit that uses the tri-fold piece of paper shock cord mount? I am always afraid it will just cut right through the shock cord mount.

You want to try and avoid using the tri-fold (tea-bag) paper shock cord mount altogether. This is because it potentially impedes the movement of the recovery system.

If you must use a tri-fold method and want to use Kevlar, you tie a loop at the end of the Kevlar that glues into the paper tri-fold. So it's the loop and knot of that loop that tugs on the paper saturated with glue, not a single strand of Kevlar.

Another option is to use a "shock lock" (see page 55 from the Handbook of Model Rocketry Seventh Edition).

There's also attaching Kevlar to the MMT, as has already been mentioned. I don't like this method because it's permanent. Someone has already mentioned a way to do with using a coffee straw so the shock cord be be inspected and replaced in the future (I think Chris Michielssen invented this...or at least helped develop and refine it). I've never used this method, but I get the impression it works pretty well with a negligible increase in weight. I wonder how well it will work when using a screw-on motor retainer; I imagine it will still work.

Lastly, if you have the vertical space in the rocket and an extra 5-7 grams of payload capability, you can use a removable baffle system and tie the Kevlar to the removable baffle.

 

[SolarYellow]

You want to try and avoid using the tri-fold (tea-bag) paper shock cord mount altogether. This is because it potentially impedes the movement of the recovery system.

I did a BT-20 build where I used 100 lb Kevlar in a tea bag mount. I used E6000 glue because it cures flexible and I wanted to avoid the pitfall of gluing Kevlar where stress is concentrated at the edge of the glue and the strength greatly reduced. Unfortunately, the E6000 stayed rubbery and does somewhat impede the loading of the streamer due to its high friction. Will be using a different method in the future.

 

[cwbullet]

Amazon has cotton sheathed elastic in 1/4 and 3/8 in bulk. https://www.amazon.com/gp/product/B004KVTS44/

I haven't found it in 1/8 anywhere.

This post discusses why cotton and links to a source with neoprene elastomer instead of the latex used by Dritz in the Amazon link above.
https://www.rocketryforum.com/threads/sources-for-1-8-wide-elastic-shock-cord.177868/#post-2391597

That is good stuff also.

 

[86mustang408w]

I got this from Amazon, lol.

 

[brockrwood]

Check this out. This is 1/6 inch (4mm) flat elastic from Amazon.

100 Yards - 1/6 inch (4mm) Flat Elastic for Sewing https://a.co/d/8dXXOss

100 yards. Would have been nice to be on a spool. Check out the weird “braid” when stretched.

 

[BEC]

How do you attach the kevlar in an Estes kit that uses the tri-fold piece of paper shock cord mount? I am always afraid it will just cut right through the shock cord mount. If I can modify the kit to use a Quest style shock cord mount, I use kevlar. If I am building it stock, I replace the rubber shock cord with elastic, just because I can lengthen it a bit and it seems to last longer.

The Estes tri-fold works fine with Kevlar and lets you use that style mount in tubes as small as BT-20. Or at least it lets me do that. It's more secure (but thicker) if you do it the original way where the shock cord is folded twice but is OK with the current way it is shown.

Lately I've ditched it in favor of FAI tan sport rubber from FAI Model Supply. Tri-fold mounting 3/32 rubber in BT-20 works with a small 'chute (9 inches or so).

Enjoy using your elastic....

 

[GusGrissom]

Check this out. This is 1/6 inch (4mm) flat elastic from Amazon.

100 Yards - 1/6 inch (4mm) Flat Elastic for Sewing https://a.co/d/8dXXOss

100 yards. Would have been nice to be on a spool. Check out the weird “braid” when stretched.

View attachment 600728

View attachment 600729

Don't strippers use that?

 

[SolarYellow]

Check this out. This is 1/6 inch (4mm) flat elastic from Amazon.

100 Yards - 1/6 inch (4mm) Flat Elastic for Sewing https://a.co/d/8dXXOss

100 yards. Would have been nice to be on a spool. Check out the weird “braid” when stretched.

View attachment 600729

4mm is ~5/32. Weird size. Looks probably weaker than standard 1/8-in elastics.

 

[brockrwood]

4mm is ~5/32. Weird size. Looks probably weaker than standard 1/8-in elastics.

Yes, it seems more decorative than strong. Still, I pulled on it pretty hard and it did not break.