Weird fabrics

Nate_Laverdure · June 24, 2022, 1:12am

This hot girl summer, it’s time to get good at weird fabrics.

I’m talking

Public transit seat cloth
Restaurant tablecloth vinyl with the flannel backing
Aluminized ripstop nylon
Advanced multi-ply fabrics with breathable membranes
Neoprene wetsuit material
Waxed duck

Let’s get into it. The weirder the better. Let’s find applications to robotics that we didn’t know were possible.

To kick us off, earlier this week I bought 40 books of fabric swatches from two of the biggest weird fabric stores.

In my first pass through the books, to get familiar with them, I first downselected the books where the fabric was available in both red and royal blue colors. I then ripped out a piece of 1000D cordura nylon. Then I ranked the books (subjectively) on the basis of slipperiness versus the scrap piece of 1000D cordura, from slipperiest to stickiest. Here were my results:

400D nylon pack cloth
Wrong side of heat sealable Oxford
70D PVC backed nylon taffeta
Diamondback composite nylon ripstop
Heat sealable Oxford
WeatherMax UV resistant polyester
Marine grade upholstery vinyl
500D cordura nylon
Wrong side of 70D PVC backed nylon taffeta
Sur Last urethane coated polyester
Neoprene wetsuit material
Taslan nylon
600x300D PVC backed nylon
1680D urethane coated Traveler
10 cotton duck
1000D cordura nylon
Wrong side of 400D and 500D cordura nylon
Wrong side of 1000D cordura nylon
Wrong side of 600x300D PVC backed nylon
Micro suede polyester
Vinyl coated polyester

Here are the books arranged roughly in that order:

What else would people like to learn about my swatch books?
Can you think of a way I can test relative resistance against slashing and puncture damage?
Are there other ways you think I should evaluate the fabrics’ friction characteristics?
What kinds of weird fabrics have you seen used in FRC?
What kinds of weird fabrics do you interact with personally and professionally?
What fabrics are the best and worst?

Nate_Laverdure · June 24, 2022, 1:38am

One of the weirder fabrics I came across recently is C-3 Fabric, a tight-weave polyester with a strand of carbon fiber running through it in a grid pattern [1], to give the fabric static dissipative properties in cleanroom environments.

I considered acquiring some to make a cool-looking equipment cover, but just went with regular ripstop nylon instead.

[1] Quite like the much-discussed infinite grid of 1-ohm resistors

Nate_Laverdure · June 24, 2022, 2:28am

This is an exciting thread but let’s pause a sec to take a look back at

Important Moments in the History of the FRC Legality of Weird Fabrics in Bumper Construction

The first thing to say is that the history of the legality of weird fabrics in FRC bumper construction is forever entangled (perhaps interwoven, heh) with the concept of “layers”.

In 2016, we see that # of layers is unlimited, as long as the bumper cross-section still looks pretty much right.

2016 - Q621
Q.According to R21 part D multiple layers of bumper cover material are permissible so long as it does not compromise the cross sectional layout and it complies with R27. Is there a limit to how many layers of fabric that may be covering the noodles at once? We were looking into a reversible bumper design that has a maximum of four layers of fabric covering part of the bumper at once.
A.There is no explicit limit on the number of fabric layers in any portion of the BUMPER provided that the crosssection is not significantly altered.

In 2018 we see people press harder for confirmation that multi-layer construction techniques are legal, and there’s a significant backpedaling as a result.

2018 - Q61 Layered Bumper Fabric
Q: Per Rules R27 and R30, bumpers are permitted to have layered fabric to ensure “each robot is able to display > Red or Blue Bumpers to match their Alliance color”, however, do the multiple layers of cloth have to be of the same material? If one were to layer (whether by sewing or adhesive) a slicker fabric (such as 200 Denier Nylon) on top of a thicker, more durable fabric (such as Cordura Duck fabric) of the same color, would this custom multilayer fabric be a legal construction for R30 D?
A: No, using 2 layers of cloth (regardless of whether they are the same or different materials) of the same color is not “needed to accommodate !R27” as either layer would accommodate !R27 on its own.
(Asked by 2410 at Jan 11th 18)

2363 gets involved for the first time at this point. We make a (IMO cheeky) reference to the rope-definition-struggles of 2017.

2018 - Q106 Understanding “layers” of bumper fabric
Q: In the context of R30D and Q61, what constitutes a single “layer” of fabric? Many commercially-available woven fabrics are constructed of several layers of flexible, non-metallic fibers sewn, twisted, tied, woven, knitted, crocheted, intertwined, or braided together. Is it acceptable to cover bumpers with a single rugged, smooth fabric constructed of fibers of two (or more) different materials provided that the cross section in Figure 8‑6 is not significantly altered?
A: A single layer of fabric, as purchased from a manufacturer, regardless of the number of layers of woven fibers, is what is intended by a “single layer of fabric.” If the manufacturer sells it as multi-layer or 2+ ply, it is not considered a single layer.
(Asked by 2363 at Jan 12th 18)

In 2020, a similar question came up again, and was answered the same way.

2020 - Q261 Multiple layers of bumper cloth clarification
Q: R24-D states, in part, “…multiple layers of cloth … are permitted if needed to accommodate R21…” which reads in part, “Each ROBOT must be able to display Red or Blue BUMPERS to MATCH their ALLIANCE color…” In order to improve the durability of our bumper cover material, and maintain the color requirement, is the use of multiple layers of the same color cloth, (eg the 200D slick bumper material from a VENDOR-not-to-be-named here) legal?
A: Use of more than a layer of BUMPER cloth for reasons other than to display Red or Blue (i.e. satisfy !R21) or to display Team Numbers (i.e.satisfy !R22) is not permitted per !R24-D.
(Asked by 5881 at Feb 7th 20)

So Triple Helix continued annoying the bear. We asked:

Q265 - Does a fabric’s weft and warp thread directions imply that it is made from multiple layers?
Q288 - Can we use excessive amounts of backer material around the areas we have embroidered our bumper numbers?

We were even joined by 3487, who asked Q267 - Can we have a 3rd color permanently installed beneath our two removable red and blue bumper colors?

These were all fun to ask, and fun to receive answers to. I encourage fellow weird fabric historians to explore the archive here.

In 2021, teams did not need to comply with bumper color and marking rules!

Were there any notable 2022 events in the history of weird fabrics in FRC bumper construction?

AllenGregoryIV · June 24, 2022, 4:59am

I think several 2022 teams choose their bumper fabric based on how it interacted with the balls and their intake. This is something we have seen before most memorably from 971 in 2017 when they used the exact wording of the rules at the time to place large numbers and first logo on their front bumper to help intake the fuel.

What fabric did people find that helped their intake the most?

wgorgen · June 24, 2022, 2:11pm

After seeing Spectrum using Dacron sail cloth for bumper material in 2019, we used it in 2020 and it was great in terms of how it interacted with the very sticky 2020 power cells.

I interact with a lot of modern sail materials. Although I suspect that these days many of them no longer qualify as “fabric”.

As far back as the early 1990s, high performance windsurfing sails were being made with sheets of Kapton film rather than fabric. I still have a bunch of these and they are still going strong.

North Sails started molding sails using a technology that they called 3DL (3D Laminated) technique where the sail was constructed on a molded shape and individual rovings of carbon fiber or kevlar or other fibers were laid down by a gantry type machine (much like 3D printing). These rovings are laminated (heat set) between a thin mylar film coverings on the front and back surface to lock the shape in place. In 2010/2011, they developed a new technique that they call 3Di where, instead of individual rovings, the sails are made by laying down tapes. The sails are still molded on a 3D form using heat to lock in the shape, but the process no longer requires the mylar films as the sails are actually a proper composite construction of fiber and resin.

Since these sail materials are properly defined as fiber reinforced composites, I suspect that they are not purely fabric any more (and would certainly not qualify as bumper material).

marshall · June 24, 2022, 2:21pm

The textile industry has a word for those. They call them fabrics.

wgorgen · June 24, 2022, 2:26pm

Well, sometimes… but I have a feeling that the GDC would have as hard a time with composite bumper material as they would with round bumpers

scubadiv3r · June 24, 2022, 2:28pm

Not exactly fabric related, but we had a bit of a tragically funny situation happen with how our bumpers interacted with the balls. We realized part way through season that the reason cargo were struggling to go through our over-the-bumper intake path was because we put our custom vinyl team number right in the middle of the bumper, and the vinyl was slick enough that the cargo were just spinning on the ground between the intake and the bumper. We ended up replacing the duck cloth and scooting our numbers to the edges and it worked like a dream, such a frustrating way for a mechanism to fail

(photo of our bumpers after they were fixed

)

Tom_Line · June 24, 2022, 3:04pm

Which is interesting because about 20 years prior to that another company pioneered using tapes along the load paths of sails.

I suspect in the future as things move along we’ll start seeing epoxy / resin with single strand printers set up so that instead of woven cloth the fibers are laid down along the load paths for sports like F1 etc.

Tom_Line · June 24, 2022, 3:09pm

Pfffft. That’s like calling a wisdom tooth extraction a procedure and open heart surgery a procedure.

wgorgen · June 24, 2022, 4:01pm

Same company. It was in 2018 when they had switched their production over to 100% 3Di. They actually produced the first 3Di sails in 2010. My bad. I edited my post.

My mind was sufficiently blown when I toured one of the lofts years ago and witnessed those sails being made.

B_Turnbull · June 24, 2022, 4:12pm

I have no idea what fabric team 4481 was using this year but they had the shiniest bumpers I’ve ever seen.

anon91718515 · June 24, 2022, 4:12pm

Interesting that you did this Nate. I have always obsessed over finding the stickiest and the slipperiest fabrics that are long-wearing and easy to work with. In the past my favorites have been:

Schoeller Keprotec, which is a Kevlar material used for motorcycle safety clothing. It has everything I like, but several drawbacks. One, it’s extremely hard to find and purchase, and two, it’s prohibitively expensive. It’s also a neutral fabric in terms of slickness, so it’s neither good for being particularly slippery nor sticky.
Yaya Han cosplay fabric, sold at Joann Fabrics, in the four-way stretch vinyls. These are great for making stunning vanity bumpers which have turned out to be surprisingly durable in general messing-around driving. We haven’t dared to use this for competition bumpers yet though.

This year, I drove to Rockywood Fabrics which is about an hour north of me and tried every single fabric they sold in blue and red. I ended up purchasing the following fabrics, which ended up on our final competition bumpers. To test them I set up a plywood platform 3’ long, and clipped a bolt of fabric to it. I had a 6" diameter disk of typical 1000D Cordura glued to a flat 5 pound weight (a lathe faceplate), which i placed on the fabric bolt and tilted until the disk slid off. I kept notes on the angle of release.

Propex Curv 600D polypropylene composite, turned inside out. It was by far the stickiest option, and we put it on the front and back ends of our bumpers.
VX21 Terrain X-Pac laminated ripstop. This was as slippery as sail cloth but much more durable. We used this on the sides of our bumpers.

If your team is interested in these products, you can purchase them through Rockywoods.

AaronUp · June 24, 2022, 7:28pm

As a professional upholsterer with hundreds of yards of fabric and thousands of sample books in my shop, this is an exciting topic.

I haven’t explored many fabric options- I mostly work with commercial and residential fabrics, but I’m happy to offer any advice or help where I can.

You’ll find most fabric has an abrasion rating- either the Wyzenbeck or Martindale test (wyzenbeck seems to be most common in the US). This is a test where the fabric is set in a buck and rubbed until two threads break, or significant wear is noticed. A standard used in upholstery is 15k double rubs is “heavy duty” and 30k double rubs for regular or commercial use.

Finding an exact abrasion resistance for 1000d Cordura isn’t easy in my searches- it’s more typically used for things like bags, tarps, etc, not as an upholstery fabric. It is very puncture and tear resistant, but there isn’t really an industry standard test for those things.

Denier is the thickness of individual threads- 1000d has a very thick thread, but most upholstery fabrics don’t use denier as a measurement. For example: I have some fabrics I use for doctors offices, malls, and restaurants that have a durability of 1 million + double rubs abrasion resistance- but you could stab a pen through it with little effort.

We’re sort of in this odd category where we are upholstering bumpers, but need fabric not typically used for upholstery. I’ve used Sunbrella in the past, which seemed to work fine for a season but didn’t have near the same puncture resistance as 1000d Cordura.

On the topic of slick vs rough fabric- I’ve been working with 500d Cordura lately and it’s noticeably more slick than 1000d. It’s relatively thin, but still a very tight weave so I would guess the puncture/tear resistance is very good.

While looking for Cordura durability, I did find these two interesting articles:

I think another thing to consider is durability of noodles, but that may be getting us off topic.

wgorgen · June 24, 2022, 8:52pm

Since the subject of puncture resistance and cut resistance came up, I thought I would elaborate on our experience with using Dacron sailcloth for bumpers in 2020. We ordered our material from Sailrite. They had a good selection of colors so we could get red and blue material. While we didn’t have a full season of wear in 2020 we did have one competition with typical rough and tumble robot to robot interaction. The 4 oz dacron cloth held up reasonably well, but I am not sure I can claim that it was better or worse than Cordura or some of the other fabrics we have used over the years.

BUT… Most sailboats have numbers on their sails as well as class symbols and sometimes other markings. These markings are normally applied to sails using stickyback dacron material. Sails are normally white and the markings are normally contrasting colors like black, blue and red. Therefore it is easy to get stickyback dacron number material in blue and red (as well as white as a contrasting color to those black molded sails). On the Sailrite page I linked above, it is referred to as insignia cloth. And since this material is designed to stick on Dacron sails, it makes excellent patching material to patch punctures and rips in the bumpers. The white material also makes excellent material for team numbers and sticks extremely well (without needing to be ironed on).

One final note: we always had difficulty damaging our competition bumpers while practicing, so in 2020 we decided to make some practice bumpers. Sailrite sells 9oz Orange Dacron material (ostensibly for storm sails) that not only provided a much stronger material than the 4 oz material on the comp bumpers, but was also in our team colors!

Mr_V · June 24, 2022, 9:59pm

To test the fabric for slashing and puncture damage I’d first take a look at Project Farm to get some ideas of DIY test rigs.

For slashing in the PF vein I’d drive a nail through a 2x4. Hinge it to a work bench, put a bolt up through the other side to hold some weights and you are ready to go. Lift up the 2x4 place your sample fabric between the nail and bench then pull it out, keep adding weight until it fails.

For puncture resistance you can build a ~1’ long bumper section, reset your rig to allow the bumper section to fit in and again increase weight until a puncture occurs.

Instead of a nail you could use a piece of some sort of extrusion as your slasher/hole puncher.

Or just make a request from PF and maybe ship your sample books to him.

Nate_Laverdure · June 25, 2022, 12:51am

PVC backed nylon taffeta is by all accounts a weird fabric, so it definitely deserves to be discussed in this thread.

It’s also a fabric that every FRC participant sees (and some get to touch!) at every in-season competition we attend, so we’re quite familiar with it already.

Here is some of the material in an atypical application:

Jared_Russell · June 25, 2022, 4:04am

You made a beverage cooler out of a blue banner?

I love it.

Nate_Laverdure · June 25, 2022, 7:29am

Thanks! It’s actually a lil tool bag that might replace the one we keep on our robot cart. Soda cans for scale.

This was a misprint banner that was replaced for us later in the season.

jaunvie · June 25, 2022, 2:05pm

It pains me I don’t have enough time to really read through all this at this exact moment. (Leaving for vacation right now) but,

We used “truck tarp” material for only our front bumper this year. Because it sticks. We used “weathermax” marine fabric for the rest. Because it’s slick. (And I could get both free. I am a marine textile fabricator)

I have looked into many sellers fabrics, (I’ll try to post an in depth look later) but my current favorite is not for the robot, but for the pits. It’s called “kanvas light”. It would love to make a 10’x10’ tent type with it.
https://kanvaslight.com/