Sewing my own chutes

[kmcquown]

If I were to sew my chutes using Ultra Thin PU Coated Waterproof Nylon Ripstop Fabric, what type of thread would I use? Would normal thread work or do I need to use Kevlar, or something else? It's just a thought. I really haven't done any cost comparison to see it it would save me any money versus purchasing them. Again, it's just a thought.

Thanks in advance for the input.

Kevin

 

[Banzai88]

I use the MARA 70 thread from my ripstop supplier, https://ripstopbytheroll.com/

About 8 stitches to the inch with just about any synthetic thread will be fine. In all the parachutes that I've made, never once have I torn the threads or a shroud line loose, the fabric fails before the thread does.

Get more thread and fabric than you think you'll use, and spend lots of time working thread tension, dog feed speed, needle size, and foot tension to get things right on scraps before sewing your masterpiece together.

 

[kmcquown]

Thanks Banzai88. Do you recommend a different fabric than what I mentioned?

 

[MCriscione]

There's really not much need to spend the extra getting a PU coated type. Grab some standard 1.1oz calandered ripstop nylon instead. The lightest, coated fabrics will be even more difficult to sew. 'Standard' 1.1 calendared is difficult enough, and plenty tough for chutes. I was doing this same thing for the first time over the summer. As far as I could tell, research found that (for chutes like ours, i.e. not skydiving parawings) having some porosity was actually better (increased Cd) compared with zero-porosity fabrics.

 

[Coop]

I generally use B or E nylon thread.

Later!

--Coop

 

[Handeman]

When you cut the nylon, use a hot knife, NOT scissors....

The hot knife melts through the nylon causing the edge to melt together and preventing any unraveling of the material. My first chute was cut with scissors and it lasted until I put it in the wash machine the first time.

I also make my gore patterns from 1/8" Hardboard. They hold up much better to the hot knife and there is much less chance of mis-cutting then when using paper patterns.

BTW, buy a cheap 25w soldering pencil and flatten the tip to a spade shape, works great. Just don't flatten it too much, it will fold and curl when hot if it's too thin.

Here's a LINK to my build thread for my biggest chute. It should give you some ideas of what chute sewing is all about.

 

[Coop]

Re: hot knife.... Just make sure you have an appropriate cutting surface to handle the heat. Also, you can only cut 1 layer at a time, as the heat will fuse multiple layers together.

Later!

--Coop

 

[kmcquown]

Thanks guys for all the helpful information. It will definitely come in handy. When I get one one done (albeit in the distant future), I'll post a picture. Thanks again.

 

[MikeyDSlagle]

Never sewn chutes but
I have a soldering iron with multiple tips, one of which is something like an exacto knife. Ive never cut ripstop but just thought it was worth mentioning. Think it came from Radio Shack. Hobby Lobby may have something similar.

Mikey D

 

[Coop]

I've found those ones aren't as good as just a long, thin, round tip for ripstop fabric. It does just fine cutting paracord, though.

Later!

--Coop

 

[stealth6]

I've made a bunch of my own chutes.
I have used Kevlar thread, but in my experience it's unnecessary overkill, and regular consumer-grade sewing machines don't like it. The thread tends to bind up and stick in the machine, due to it being stiff and coarse compared to "normal" thread. On the other hand, I've also used regular old standard sewing thread which always worked perfectly fine....easy to work with, cheap, readily available, sews just fine, and I've never had any actual problems in use/flight with it.

The suggestion for using 1.1 calendered ripstop is a good one. All my best chutes (by far) were made with this material. It's wicked light, packs tiny, opens easily in use, and performs great. That said, it IS kinda tricky to sew - mainly due to it being so slick. In sewing, it's very slippery and extra care is needed running it through your machine. I've found good deals on E(vil)bay for the material.

s6

 

[MikeyDSlagle]

I've found those ones aren't as good as just a long, thin, round tip for ripstop fabric. It does just fine cutting paracord, though.

Later!

--Coop

Yeah I can see where there may be some issues with it on fabric. So far I have only used it to cut plastic mesh wire loom.

 

[ttabbal]

Never sewn chutes but
I have a soldering iron with multiple tips, one of which is something like an exacto knife. Ive never cut ripstop but just thought it was worth mentioning. Think it came from Radio Shack. Hobby Lobby may have something similar.

Mikey D

I have an el-cheapo soldering iron from Harbor Freight I use for this sort of thing. Cutting foams it's really handy. Pretty sure I paid all of $5 for it.

 

[AlphaHybrids]

Re: hot knife.... Just make sure you have an appropriate cutting surface to handle the heat. Also, you can only cut 1 layer at a time, as the heat will fuse multiple layers together.

I actually cut one side of the pattern out using 1/8 hardboard so that it WILL fuse it together. Then you already have one seam of your parachute basted together and it goes through the machine much, much, much easier.

If you can't cut them and fuse at the same time, then what I do is lay them together and melt the edges together so they are basted. You'd find that you get better quality that way because it doesn't slip when sewing.

Edward

 

[Handeman]

I actually cut one side of the pattern out using 1/8 hardboard so that it WILL fuse it together. Then you already have one seam of your parachute basted together and it goes through the machine much, much, much easier.

If you can't cut them and fuse at the same time, then what I do is lay them together and melt the edges together so they are basted. You'd find that you get better quality that way because it doesn't slip when sewing.

Edward

I hadn't though to doing that, but great idea!

 

[Coop]

I actually cut one side of the pattern out using 1/8 hardboard so that it WILL fuse it together. Then you already have one seam of your parachute basted together and it goes through the machine much, much, much easier.

If you can't cut them and fuse at the same time, then what I do is lay them together and melt the edges together so they are basted. You'd find that you get better quality that way because it doesn't slip when sewing.

Edward

I suppose that would work, depending upon the type of seam you're making. I don't find that slipping is really much of a problem on my machines. They all seem to feed the material quite well.


Later!

--Coop

 

[AlphaHybrids]

I started out making the felled seam for all my parachutes. The I found a rolled hem foot. That is what I use now. I have a 1/4" rolled hem foot that I use for all the gores with bias tape on the edges. As for strength, I've found the joint to be stronger than the fabric every time it has been tested. Last weekend a parachute met it's fate when a rocket came in ballistic and the parachute deployed at just over 600 fps. Shroud lines held where they were sewn, seams held where they were sewn, parachute fabric ripped between gores where it was not sewn. I've observed this multiple times when a parachute has opened under non-ideal conditions and failed. A rolled hem seam is also much faster, as the fabric can be melt-basted or tacked and then ran though the machine in one step to complete the seam.

Edward

 

[T-Rex]

Thank you for the good info here! I have a brand new TFR X-type that a puppy chewed the lines off of. (Yep, just the lines, fabric is perfect). I have been thinking that it is time I attempted to attach some new lines and fly it. TFR will put new lines on, but the cost was similar to the cost of a whole new chute, so it has been sitting in a drawer....

 

[soopirV]

I started out making the felled seam for all my parachutes. The I found a rolled hem foot. That is what I use now. I have a 1/4" rolled hem foot that I use for all the gores with bias tape on the edges. As for strength, I've found the joint to be stronger than the fabric every time it has been tested. Last weekend a parachute met it's fate when a rocket came in ballistic and the parachute deployed at just over 600 fps. Shroud lines held where they were sewn, seams held where they were sewn, parachute fabric ripped between gores where it was not sewn. I've observed this multiple times when a parachute has opened under non-ideal conditions and failed. A rolled hem seam is also much faster, as the fabric can be melt-basted or tacked and then ran though the machine in one step to complete the seam.

Edward

I would LOVE to see a video of this, if you were willing and able to make one? I'm a novice with sewing, but my mother-in-law is a veritable seamstress...I may be able to either get a lesson, or even puppy-dog-eye my way into picking them up finished

 

[dixontj93060]

I would LOVE to see a video of this, if you were willing and able to make one?...

Me too!

 

[AlphaHybrids]

I'll find a couple pieces of fabric and run it through the machine for you all.

Edward

 

[crossfire]

What happens with the sewing machines that most people have is Kevlar the thread will cut into metal parts of the machine and cause it to hang up and get stuck. You don't need Kevlar thread. We have never used it in 25 years of making chutes. If sewed right the fabric or shroud lines will fail first.

 

[Coop]

What happens with the sewing machines that most people have is Kevlar the thread will cut into metal parts of the machine and cause it to hang up and get stuck. You don't need Kevlar thread. We have never used it in 25 years of making chutes. If sewed right the fabric or shroud lines will fail first.

"Metal" being a bit generous... Those with plastic where metal ought to be are really asking their machine to take four or five steps beyond that which it is designed for. For a general rule--if you can lift your sewing machine with one hand, you probably should not use Kevlar thread in it.

Later!

--Coop

 

[raptor22]

I have a comment on the fabric discussion:

Some of the members of our collegiate rocketry team did a bunch of windtunnel tests on parachutes they sewed last semester. Using a low porosity fabric recommended by an advisor at the local "dropzone" yielded a 25% increase in drag when compared to an equivalent fruitychutes design. That low porosity fabric was also measurably worse in performance than zero-porosity, but the stability was far better.

Careful selection of fabric for porosity might not be necessary for rocket parachutes but it seems to offer some significant improvements.

 

[Handeman]

That low porosity fabric was also measurably worse in performance than zero-porosity, but the stability was far better.

Was the low-porosity compared to zero-porosity with a spill hole? The spill hole should increase the stability of the zero-porosity chute. I would be very interested if it drops the Cd down to where the Cd was for the low-porosity chute and if there is a size as a percentage of chute area where you get stability in the zero-porosity but still better Cd then the low-porosity.