Bumper Material
 

Hello CD, My team has come to the recognition that we want to start using the "Slicker" bumper material. The material when contacted with other bumpers will cause less friction, which is what our team wants. I know that team 971 The Spartans use it and I'm sure many other teams use it also. If you could just reply with the name of the material or the website that you get it from. Thanks!:D

Re: Bumper Material
 

I know team 67 used a pleather (foe leather) material on their bumpers. Adam Freeman shared a link on another thread

http://www.joann.com/pleather/xprd757783.html

Thread: http://www.chiefdelphi.com/forums/sh...d.php?t=127938

They looked amazing.

Re: Bumper Material
 

We've flipped the Cordura fabric and used what would be considered the back of the fabric as the front whenever we've wanted a slipperier surface.

Re: Bumper Material
 

971 used a material called Ballistic Nylon this year, and it helped us enormously in getting out of friction pins. Our entire drivebase design, from the shape to the bumper material helped us evade defense and was a big reason why we were so successful.

Ballistic Nylon has a coefficient of friction of 0.3 on the normal Cordura, compared to a coefficient of friction of 0.5 of Cordura on Cordura. It terns out this difference is enough to get out of most pins. Our testing showed that we could drive out of pins even without an octagonal shape.

Many other teams have used low friction bumpers this season and in the past. 1678 and 1717 both used the Ballistic Nylon fabric this year. Other teams (and they will have to correct me if I get these fabrics wrong) include 1114 and 148 using sailcloth and 2056 using some kind of vinal. For championship, 254 decided to change from Cordura to sailcloth, and it really upped there performance. They were much harder to defend at championship than at SVR or on the practice field. Sailcloth has a coefficient of friction of 0.25 on Cordura, but tends to be more expensive that Ballistic Nylon. It is also less durable than Ballistic Nylon.

We also experimented with using Sailkote on our bumpers (Sailkote is a sail lubricant for those who don't know). This seems to only help significantly with the actual sail fabric, and take the coefficient of friction on Cordura down to 0.2 from 0.25. However, we'd likely need to get some sort of Q+A ruling to do that to be safe, as it becomes a user applied material to the fabric. We tried spraying it on Ballistic Nylon and it did not work well enough to justify the effort involved and the extra cost.

Some low friction materials are not as sturdy as Cordura, which is why we did not use them. We did stress testing on the Ballistic Nylon and found that it was about as strong as Cordura. Ballistic Nylon does wear, but not to the extent that it would not be considered a "smooth, rugged material" as specified in the manual. Materials like silk are slippery, but just fall apart during the rigors of FRC gameplay.

Also, a note on the pleather material that HOT uses: they would be better served to talk about this than me, but I was talking to Mike Schreiber at championships, and he mentioned that pleather is very slippery on Cordura, but gets stuck to field elements. The positive of these other materials is that generally doesn't happen.

There's been a lot of advancement in bumper materials over the last couple years, and it definitely makes a difference in on field performance.

Hope this helps.

Re: Bumper Material
 

The Pleather was very slippery on the Cordura, but the combination of it's stickyness on the walls and the degraded appearance (stretching) after aggressive play, we will not be using it moving forward into 2015.

I am most hopeful to find the sail cloth material that 254 used, since it had a great appearance all through Champs, and was extremely slippery.

As Kevin mentioned, their Ballistics Nylon material also seemed like a great material that was very durable, good looking, and slippery.

I will say that I think the bumper material is really the icing on the cake to a properly designed drivetrain and driver training. Effective drive design for # of wheels, wheel type, track width, wheelbase, etc... are probably far more important than finding the very best bumper cover material. Even with the slippery material that we had this year, we had a drivetrain that was extremely succeptible to t-bones, side pins, being pushed off course, etc... We will be working this summer and next year to design a better drivetrain that can either get out of and/or make it harder for us to get stuck in these situations. I don't think we know exactly how to do this, but we have some ideas.

Re: Bumper Material
 

How did the teams with alternate bumper material feel about their ability to defend (namely "friction pin") other teams?

Re: Bumper Material
 

Just as it was harder to lock us up, it was definitely harder to friction pin teams. We "tried" to play more of a positional defense on in-bounders and scorers to not let them get to their desired spot...but once they got around, we had a hard time holding.

It didn't effect us too much, since we were usually playing defense while waiting for the ball to advance or get scored, so we were only doing it to try and add time to cycles...not completely shut teams down.

My opinion (as a mostly offensive team) is the slippery bumper could help give that little edge to save a split second to get into position to score quickly. I subjectively feel they are more of a benefit to an offensive team, than a detriment to a defensive team.

If I wanted to build a defensive machine, I would stick with the Cordura. Cordura on Cordura seems to be like velco "hook and loop" on the field.

Just my $0.02

Re: Bumper Material
 

Our bumper making team will not be happy when I suggest we make four sets of bumpers next year...

Re: Bumper Material
 

Direct friction pinning is generally harder to do with lower friction bumpers, but we were still able to play effective, and in some cases more effective defense than we did last year. This was mainly due to the octagonal shape, as we we able to more easily get the front of our robot onto another robot and into a pinning position. We could also pivot and use the side of the drivetrain to block a robot from escaping.

One thing to consider for a defense robot is the opposing alliance's ability to play counter defense on it. It will actually be harder to play counter defense on a robot that has lower friction bumpers, so it isn't necessarily a bad idea to go all in on low friction bumpers. If you want to make a T-bone machine, go for the Cordura. However, there are things you can do with robot design that will make a lower friction bumper defensive robot just as or more effective than one with higher friction bumpers.

Though, to expand off of Adam's comments, a better bumper material won't be the difference between fielding a bad drivetrain and a good drivetrain. A lot of the teams doing it are chasing that last 1-5%. Making sure you prioritize drivetrain design is a better goal for most teams to focus on. That being said, it's probably easier to change you bumper material than it is to design a new drivetrain. It's just important to keep in mind there are many factors that go into building top notch drivetrains.

Re: Bumper Material
 

Well, if you're going to make 4 sets, why not make a 5th set that's just for display?

Re: Bumper Material
 

What about cordura on the front and back, and sailcloth or ballistic nylon on the sides? Best of both worlds.

Re: Bumper Material
 

This is certainly possible, and something we considered (albeit very briefly) for this season. One issue is that the colors all the fabrics come in are quite different, so while you might get the desired functionality, the aesthetics of you bumper would arguably not be as good. We considered having higher friction material in the front of our robot to aid in ball pickup, but we tested our prototypes with lower friction material and it wasn't a problem.

Additionally, lower friction bumpers doesn't just help you get out of friction pins as the colloquial definition of a "friction pin" would dictate. Having a lower friction bumper material simply helps you avoid getting caught or slowed down on other robots and field elements, and this can be a benefit to not just avoiding pinning, but also to ensure better mobility around the field. As such, having lower friction bumpers on all sides of your robot.

To explain our reasoning, we realized that having ballistic nylon could limit our ability to pin other robots, but we felt that our defensive abilities were not limited to just pinning people. Our driver(s) and our drivetrains are far more versatile than that, and we have other defensive play in our playbook. Therefore, and costs were outweighed by the large benefits. This year, we still think we were able to play effective defense, and we didn't feel we were hurt by having lower friction bumpers.

Re: Bumper Material
 

Why not use the recommended bumper material like everyone else? I'm surprised FIRST hasn't put the hammer down on the exact material that must be used (rather than recommended).

Re: Bumper Material
 

They are following the rules EXACTLY. They are using rugged, smooth cloth.

Nothing wrong here at all.

Re: Bumper Material
 

What's wrong with engineering better bumpers? If they feel their robot performs better with a different fabric, I don't see any major concerns because they still serve the same function: protecting the robot and other robots.

Re: Bumper Material
 

While Cordura makes for good luggage, it makes for terribly boring robot matches when half the field is friction pinned for the entirety of the match.

Re: Bumper Material
 

I'm not saying they aren't following the rules.

Are the bumpers really doing their job better? Do they protect your robot any better than bumpers made from the standard material? The intent of the bumpers weren't to make it easier/harder to pin people. The entire intent was so that your robot (and mine) were better protected against collision.

Re: Bumper Material
 

On the other hand, does this different fabric protect the robot any less?

Re: Bumper Material
 

I know we're talking semantics, but that's a different question.

I would argue that the reason for the leeway in the bumper material rules is in the case a team isn't able to obtain the exact material specified, not to provide a means of gaining an advantage.

Re: Bumper Material
 

If you were to run a four piece bumper system, could you just have the higher grip fabric on the front and back bumpers so you can play defense, and have the slick fabric on the side bumpers to get out of defense and friction pins?

Re: Bumper Material
 

Has anyone used Silicone fabric spray (used to reduce friction in sewing) on their bumpers? I believe it would still meet the letter of the rules (it wouldn't make sense that you could buy treated fabric, but couldn't treat your own).
http://www.nancysnotions.com/product...icone+spray.do

Re: Bumper Material
 

Oh OK, I see your point. I think of it as minimizing a side effect of the bumpers. While they are meant to protect the robot, they introduce a new flaw in a robot inadvertently. It's like another challenge teams have to overcome.

Also I think the recent surge in defensive play and the need for speed and maneuverability have contributed to this. Some teams have mechanically adjusted for this with either omni or caster wheels, while others have looked to new frame shapes to avoid direct contact or low friction bumpers, especially teams that use tank drives.

Re: Bumper Material
 

In terms of whether teams should just use the recommended material because that is what is recommended, I would respectfully disagree. Arguably, the recommended bumper material follows the rules less than these other materials. The rules specify that a smooth and rugged material must be used, and the colors must match those of the FIRST logo to a reasonably astute observer. Having a lower coefficient of friction means that these fabrics are smoother than Cordura. As I mentioned before, we also tested the fabric to make sure it was suitably rugged. Multiple smooth fabrics we tested out we decided against using because of this requirement. We feel we have found a solution that is well within the rules that also gives us an advantage, which is really how it should be.

Now, if someone decided to take this another way, and use fabric that had more friction instead of less, that would be a bit more of an issue. At some point, it ceases to be a smooth material and starts becoming something that you design to deliberately catch on other robots. I have a feeling FIRST would rule against something like this.

Another note: in terms simply using the recommended fabric, it is clearly stated in the rules that it is a recommendation, not a requirement, which could change of course. However, if teams were to just do as recommended, there would be much less innovation and thoughtful design in FIRST. There are certainly other teams that use alternate bumper fabric, but the teams I mentioned (1114, 2056, 1678, 1717, 254) are all amazing teams. They have seen a part of the rules (arguably a loophole, though I think not) that they can use to field an ever more competitive robot. Before now, not many teams have even considered bumpers or bumper fabrics an area for innovation. Good teams always find ways to innovate. They work to find creative solutions to real problems, in this case the large amount of friction pins in a wide open game. People might not like it, but I see it as a way to create a better design in a creative way.

I would actually argue that having a smoother bumper material can result in benefits for safety. Less robots caught on other robots and on field elements smooths out gameplay and makes it harder for other robots to use their bumpers as a wedge to get under other robots. It's hard to tell whether it would result in dramatically safer matches, but overall it could be good for FIRST to have more lower friction bumpers out there.

Re: Bumper Material
 

I agree, FIRST as a whole would be a lot more fun if more teams used slick bumpers. Cordura should not be the gold standard of bumper material. It should be ballistic nylon, sail cloth or equivalent. Watching pinning is very boring and not inspiring.

Re: Bumper Material
 

This one's a real stretch. Even if you can find a way to overcome the R21 problems (BUMPERS must be constructed in accordance with Fig 4-8), you still face this issue:
I know this rains on everyone's parade.

Re: Bumper Material
 

To be fair, we did this testing before the season even started, and made the decision not to use anything before the rules came out. I know other teams have tried to use sailkote in the past, but we wanted to collect data on what the effect would be. It was mainly for experimental purposes. I probably should have phrased it better.

Asking the question on the Q+A would likely result in a ruling against sailkote, so asking the Q+A "to be safe" wasn't exactly the right choice of words. That we would ask the Q+A before proceeding is probably a better description of how we would treat the situation, if it ever came up.

Re: Bumper Material
 

Would you say a solid lubricant contravenes that rule? A silicone or teflon spray dries hard and does not transfer to other objects. If you still object, be sure none of your bumper materials have stain-resistant treatments from the factory which amount to the same thing.

Re: Bumper Material
 

For the purposes of FRC rules, it's not the same thing at all. If the stain-resistant treatment is applied at the factory, it is part of the rugged, smooth cloth, and thus perfectly legal (given that all other applicable rules are followed).

If you apply it at your shop, it is NOT part of the rugged, smooth cloth, it is an added product that may or may not be legal depending on what the GDC has ruled.

It's like using a metal hose from the compressor to the first fitting. If a team decides to buy a metal pneumatic hose/tube (larger than allowed tubing, most likely), attach it to their compressor, and try to pass inspection, chances are it'll be ruled an illegal part. HOWEVER, if that same metal hose comes with the compressor and the MANUFACTURER says that the compressor needs to be used with that hose, then it is ruled part of the compressor! (And yes, the GDC did make that exact ruling in a Q&A--though not in the same words.)

The difference is slight, but it makes a huge difference in whether you're playing or not.

Oh, and on the solid lubricant: I would consider it to be in violation if the GDC had ruled that bumpers had to be constructed per the rule and that adding stuff to the cloth to modify its effects was illegal (as I recall, they made enough statements that tended to go that way that I'd be pretty comfortable with a "no pass" call, probably with a side of "LRI to confirm"). Remember, though, what I said earlier: If the cloth comes that way from the manufacturer, it's legal (unless the GDC has ruled otherwise).

Re: Bumper Material
 

Sounds like a great new revenue stream for the AndyMark Fabrics Division.

Re: Bumper Material
 

Exactly. Placing the division at "comes that way from the factory" is silly (although I recognize that may be the way it is). In that case I would happily have my local fabric store apply the coating, then offer it back to me as a "commercial part". It would be counterproductive to FIRST goals to have rules that discourage in-house fabrication but allow purchasing the same item from 3rd parties.

Please note that this question is purely academic for this year - We didn't modify our fabric at all. I'm thinking about next year.

Re: Bumper Material
 

I think it is time to revive this discussion. Has anyone come up with a better bumper fabric material that they would care to share?

We're experimenting with sailcloth now. We're also looking into embroidering the numbers rather than painting them.

I'm curious to see what revisions FIRST makes to the rules this year for bumpers. They need to be easier for rookie teams to implement and for veteran teams to assist with. We advocated to Andy to make some corner brackets to make them easier to build. He had a prototype at CMP that was pretty cool but no word yet on whether they will be building it or teams will be able to buy it. I'm hoping for it personally.

Re: Bumper Material
 

Are you talking about this and/or this? If so, they are available now. And have you felt the iron on number that came in the kit? We have used them for the two previous years and they are pretty slick against standard Cordura nylon. I haven't had a chance to test sailcloth or ballistic nylon but I would imagine it would be just as slippery.

Re: Bumper Material
 

We have been embroidering numbers on bumpers for some time. You have to be sure to specify stroke width & height to the embroiderer. I looks great & durable. I am not sure if it helps or hurts in T-Bone situations.

Re: Bumper Material
 

When I had the ear of an AndyMark engineer at this year's Global Community Conference I pushed hard for them to make an include a bracket system for the up coming season's chassis. He did say it was something that was worth consideration.

Those are for the old C-base and would not work with the most recent AM14U and since the 2015 drive base is reported to be the AM14U2 it seems unlikely they would work for it either.

Re: Bumper Material
 

What about making our own high-durability 'cloth' out of UHMW tape backed by aircraft-grade duct tape?

Has anyone tested sailcloth-on-sailcloth friction (sorry for not searching)?

The Cordura, under rough FRC conditions, seems to have the puncture resistance of a balloon... There are 2 'cuts' in our bumpers this year after years of having nothing wrong.

Re: Bumper Material
 

I was not talking about either of those but rather something entirely new. Andy had a 3D printed version of it that was cool and the inspectors were all eyeballing in St Louis. Hard to describe but basically an extrusion profile that allows two boards to be fit into it at 90 degrees to each other. It would definitely simplify the bumper corner construction process for teams, at least we think so.

We tried the iron on numbers in the kit but had no luck with them. I'm not going to claim we put them on correctly mind you but we really couldn't get them to stick. We opted for paint this past year since we had used it previously. That and the standard bumper fabric.

We are aiming to do more this year... assuming the rules allow for it.

How about pool noodles? Who is using hollow core and who is using solid core?

Re: Bumper Material
 

Ah, I see what you are saying. Yeah they are quite tricky to put on.

Re: Bumper Material
 

We got our bumpers screen-printed this year and used the same fabric (a tougher, slicker alt to Cordura, no idea where it came from unfortunately) and the blue covers came back from Alamo just fine but the red ones were totally rekt from the rough play. No other issues.

We need to get new bumper material, but I don't want to dump money into bumpers in case any of the rumored changes come to pass.

Not buying into any conspiracies, just that bumpers are a very specific assembly in FRC and the cloth for them doesn't really serve a different purpose, and plywood and noodles aren't preferred building materials for other stuff on the robot.

Re: Bumper Material
 

Congratulations, you just figured out the game hint. 2015 will be Arial assist without bumpers & unlimited CIMs on the drive train. The name will be "Rockem Sockem"

Re: Bumper Material
 

We use a t-shirt press and t-shirt vinyl like Siser Easy Weed. The key to getting them to stick is to use even pressure. An iron is a really bad tool for that. See if there is a local place that will press them for you. Any custom clothing shop should be able to do it for pretty cheap. You only need 8 sets of numbers and 8 presses, so compare that to having 8 t-shirts made. Even if they charge you and cut the vinyl I would have a hard time believing it would be more than $50. I have all of the stuff in my classroom so it is pretty simple for us.

Re: Bumper Material
 

Didn't get to see any of the teams that used "SailCloth" Or "Ballistic Nylon" up close but I am definitely interested in trying to find ways of keeping robots mobile when others are trying to immobilize them. I'd love to try some of these out.

Does anyone have links to online sources for either of these?

A Google search pointed me to here for "sailcloth" (Red / Blue). Here is another variety of Dacron sailcloth that comes in red and blue that looks FIRST legal. Are any of these materials the ones that teams used successfully.

As to "Ballistic Nylon" there seems to be a 1050 variety and a 1680D variety. The 1050 doesn't seem to come in Red & Blue (or at least I couldn't find it). The 1680D has some shades of red and blue that seem to be FIRST legal for bumpers (link here)

Same question to folks. Is this the Ballistic Nylon folks have used or is there something else I should be looking for?

Do tell.

Joe J.

Re: Bumper Material
 

Team 1126 used a combination of sailcloth bumpers on the side with cordura on our front and back bumpers. This allowed us to use friction to our advantage to pin and escape from a pin. We also use the reversible bumpers (blue on one side, undo some velcro and flip it to red).

We changed our bumper material between events and saw a noticeable difference in our ability to get through defense. If anyone has any questions let me know!

Re: Bumper Material
 

The first link is for lightweight 3/4 oz cloth used for spinnakers. It will rip with the slightest snag on something sharp. The second link for 4oz dacron is what you want. There are tons of sailcoth types and weights available, I'd recommend visiting a local sail loft and feeling it first hand.

Re: Bumper Material
 

Last season we used the 1680 that you linked to.

I think that some people are getting their sail cloth from Seattle Fabrics. You may need to call to get the blue and red Dacron because their website is pretty sparse.

Re: Bumper Material
 

Just out of curiosity, has anyone found a high CoF, tear resistant cloth that a dedicated defensive robot could use? (basically the flip side of what Dr. Joe is asking)

Re: Bumper Material
 

P.S. I hate you. ;-) Just kidding. Bring it on...

Re: Bumper Material
 

Or maybe it will be Aerial Assist with mandatory football-shaped frame perimeter

()

and ultra slippery bumpers. The name will be "Greased Pig".

Re: Bumper Material
 

I believe 67 had a really sticky bumper to start out in 2014 (someone mentioned they were pleather), but ended up having difficulties moving when pinned against the sides.

Re: Bumper Material
 

It was discussed slightly in this thread. I agree with Nate that the best option would be a coated nylon fabric. I have seen vinyl, polyurethane, silicone, and neoprene coated nylon. However, many of these are created for waterproofing and not strength. While quite thin at 1.9 oz., the silicone impregnated nylon looks promising. I might order a sample to do some testing.

Re: Bumper Material
 

Looks like that is a 70 Denier fabric. The Cordura commonly used in FIRST is likely at 1000 Denier, so it is 10X heaver thread (~3X thicker fabric). Based on that (and the description/recommended uses), I bet that the 70D will get torn apart.

Re: Bumper Material
 

It most likely will. I have only been able to find 1000D nylon with a polyurethane coating.

Re: Bumper Material
 

How can it follow the rule less than other materials if it is in the rule?
The 1000D Cordura is recommended because we know it is durable and won't easily tear. It has nothing to do with dictating robot to robot interactions for some desirable effect. The parts of the bumper system were chosen for one reason and that is to prevent robots from being beaten on to the point where they can't play. The system was derived from testing robots running full speed into immovable objects with no frame damage. The materials were chosen to be easily obtained by most teams and to not break the bank for purchase. If you choose to use more than one bumper system, all of them need to be inspected, weighed and recorded. Have fun everyone.

Re: Bumper Material
 

We at Robopromo have every kind of bumper material you could want or need - from offensive to defensive to everything in between. We've got pre-sewn corner bumpers, pre-sewn reversible bumpers (in offensive and standard), and a variety of other kits and fabrics. Check us out at robopromo.com.