can you use Carbon Fibre?

[Greg Perkins]

hey CD,

I was wondering, can you use Carbon Fibre? or is it considered a Exotic Material like titanium?

[Lord Nerdlinger]

Originally Posted by Greg Perkins

hey CD,

I was wondering, can you use Carbon Fibre? or is it considered a Exotic Material like titanium?

i'm not 100 percent sure, but i don't think you can. Also the cost would be tremendous

[Cory]

Following the flowchart, you are allowed to use it, since they removed the part about exotic materials.

Cory

[SarahB]

Originally Posted by Lord Nerdlinger

i'm not 100 percent sure, but i don't think you can. Also the cost would be tremendous

If you don't know, you shouldn't answer.

As the rules read now, you can use carbon fibre on the robot as long as it is accounted for in the budget and it isn't likely to damage the field or other robots. See the flowchart on page 10 of section 5-The Robot.

[KenWittlief]

personally I would not recommend it - when it cracks or splinters it produces very nasty little needles that can get in your skin and cause all kinds of health problems

sorta like fiberglass with a bad attitude!

[ChrisH]

Originally Posted by SarahB

If you don't know, you shouldn't answer.

As the rules read now, you can use carbon fibre on the robot as long as it is accounted for in the budget and it isn't likely to damage the field or other robots. See the flowchart on page 10 of section 5-The Robot.

There is also the rule against hazardous materials. Sorry I forget the number. While carbon fiber is not terribly toxic, the resins you use to support it are. There are carbon fibers on the market in a form that would be affordable to a FIRST team, if used properly. So cost may not be the issue you think it is if you know where to buy and how to take best advantage of them.

But consider this:

I am a professional engineer who has spent more than 20 years building things out of graphite epoxy and other composite materials. I am an expert at what I do. I not only can make straight things, I can make shapes the metals guys ony dream about, and I do it routinely. I have a 300 lb stash of "scrap" carbon fiber at work that I can use for "free" (Aside from accounting for the raw material cost of course). We have applications on our robot this year that positively cry out to be made from composite materials. BUT WE ARE NOT USING THEM.

Because I can't figure a way to do so in our facility without exposing somebody (including me) to hazardous materials.

At work, we have a facility that is set up to handle this stuff and people who monitor the way we use it, to minimize the hazards. But it is never safe and because of the way the chemicals attack your system, it may be twenty years before you find out you just made a big mistake. Maybe I just know too much about it ... but right now I don't think it is worth the risk.

BTW if you MUST use a composite, use fiberglass. The machining is much more straightforwards as you do not need special cutters as much. It is also stronger than, (Surprise!!!) but not as weight efficient or stiff as, carbon. It is also much cheaper.

If you want to try something, let me know and I'll tell you what I think what you're doing. Though I'll probably try and talk you out of it.

Even if something is "legal" to do, it may not be wise.

ChrisH

[Cory]

Chris brought up some good points. I felt a need to elaborate on some of them.

I am an avid mountain biker. Some components, mainly handlebars and seatposts are made of carbon fiber to save weight, and improve stiffness (Some manufacturers make complete bicycle frames as well).

Chris pointed out that Carbon fiber is not as strong as fiberglass, but stiffer. Be aware that carbon fiber does not give any warning signs of impending failure. It looks just fine and all of the sudden it snaps in two.

If you put even a small scratch into a carbon fiber handlebar, there is a high probability that it could catastrophically fail, and possibly severely injure you.

Obviously on robots, you wont be severely injured if it fails, but there is likely to be lots of robot on robot contact. If you're constantly scuffing up carbon fiber that is used as a structural material, it is likely that it will fail.

Some things to keep in mind

Cory

[Greg Perkins]

Well, i thank you all for the answers..


but i am an avid battlecombat robot builder, and carbon fibre is an excellent material. its light, and strong. and despite what you guys say, its easy to machine with a simple jigsaw, or a badsaw. i know, i worked with it on many robots. it is also reasonably priced.

I had proposed the idea of making "god plate" which is pretty much the place where everything is mounted...it would go along nicely with the flow of the robot.

[ChrisH]

Originally Posted by Greg Perkins

Well, i thank you all for the answers..


but i am an avid battlecombat robot builder, and carbon fibre is an excellent material. its light, and strong. and despite what you guys say, its easy to machine with a simple jigsaw, or a badsaw. i know, i worked with it on many robots. it is also reasonably priced.

I had proposed the idea of making "god plate" which is pretty much the place where everything is mounted...it would go along nicely with the flow of the robot.

Depending on the resin, you can get away with a bandsaw for some cutting with the proper blade choice, especially if you're willing to put up with a few splinters. I tend to use high temp resins that are little more finicky when it comes to machining. We can also scrap a $1M part for a few splinters in the wrong place , a problem which you may not worry about quite so much. Consequently we are pretty picky about how we do our machining.

If you use graphite/epoxy plate stock that comes pre-cured, then there is probably no issue. Cured composites are not generally considered hazardous, it is the uncured resin and particularly the hardeners that are dangerous. You still have the splinter issue, but many stock plates come with a fiberglass outer ply to reduce splintering. A lot of bike parts include this now as well. The glass is practically invisible and it's presence may not be mentioned by the manufacturer or distributor. I know what to look for and have been unable to find it at times, even when I know it is there. So the casual observer can be excused for not noticing it.

A couple of minor concerns to add. Graphite composites are conductive. I wouldn't mount any electronics on them unless you take special precautions to keep things electrically isolated. That includes isolating the scews and bolts holding things down too. Also grapite and aluminum are a galvanic pair. That means that if you get them wet and they are in contact, the aluminum will eat at the graphite. This is a HUGE problem for aircraft that fly off of carriers, but probably not too big a deal for a FIRST robot, unless you have your shop/ storage area 50 yds from the beach in an un-heated building like we do. This can be prevented by ensuring that the fiber and the aluminum never come in contact, another reason for a glass outer ply.

From your original question I thought you were intending to do you own layup. While this can be done with materials that have been legal previously, like epoxy resin, the new rule against using hazardous materials is unclear as to just what level of hazard is acceptable. Everything is hazardous under the right conditions.

Again I might just be a little paranoid here. After all the hazardous materials list where I work includes such items as nitrogen (70% of what you are breathing but too much is deadly), sodium chloride (if you eat too much you can get sick), corn oil (they use it in food, I don't know why it's on the list), Aluminum (as a powder it is a hazard and they wouldn't let me use it!) and my personal favorite, de-ionized water (if you breathe too much it is bad for you).

[Joel J]

Originally Posted by ChrisH

... and my personal favorite, de-ionized water (if you breath too much it is bad for you).

Ahaha.