Hey, guys, Fermin here from 6017
We’re interested in implementing CF on our future robots, I wanted to know how you use it within your robots, and maybe get some tips, on where to get it, and how you machine it.
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For CF sheets, I’ve gotten them from cnc madness, at least in my scenario, it beat out the price of sourcing our own cf and manufacturing it ourself.
However, I wouldn’t suggest using a significant CF in FRC unless you can get it for super cheap or get sponsored by a CF supplier. CF, while strong and stiff, is brittle and will not absorb a significant amount of energy in an impact, and FRC robots don’t care that much about weight. For superstructure mechansism, this may be fine if they stay within the frame peri, but for many other mechanisms, it is a significant risk. CF tube for arms with proper mitigations or camera mounts is fine, but for elevators/arms that have intakes on them that can get hit, you can end up in serious trouble.
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There was a thread a few months back on this very topic, lemme see if I can find it
edit: Ok, here is an older one:
I think looking around to what other teams have done with tha material is a good start. It is a cool material for sure, but far from the end all and be all.
Check out teams 33 and 67 for some good uses of CF and keep an eye on what manufacturing techniques were required. 2767 has done some cool things with it as well that really take advantage of the properties (2023 btb) where they “twisted” the elevator/arm frame for fine tuning gamepiece placement.
One of 67’s tricks, iirc, is to design around common sizes for drones. It makes it much more economical.
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The main thing to keep in mind is that CF, like any material, has strengths and weaknesses (see the Titan Submersible).
CF is very good for tensile and flexural loads where you need the part to be stiff and lightweight. Common uses are things like game piece handleing rollers, mid/low load but high stuffiness bars (camera mount struts, amp deflector bars from this year, etc) and some strutural applications like 971’s 2023 arm. Again, the biggest bonuses of CF are its stuffiness and weight (or, more accurately, lack thereof). There are a ton of great uses for it if you are creative enough.
All of that said, keep in mind, cf isnt a magic bullet, it perforns pousrly at compressive loads and tebds to fail suddenly, so its important to use it when it fits best as a material, particularly considering its non-trivial cost.
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I’ve worked a lot with carbon fiber since i’m an aerospace engineering major at my school. Working with Carbon Fiber/composits is very difficult and dangerous. Drilling holes through it is difficult and and particles created from machining are extremely dangerous to inhale. Any student at my school who wants to work with composites is required to wear an inhaler.
I would HIGHLY HIGHLY suggest if you really want to having a sponsor or professional company do the manufacturing for you because in order to do it safely is going to cost a lot of money.
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CF is only worth it if you’re optimizing for the final 0.1% performance on your robot. It’s difficult (and potentially dangerous) to manufacture and you can use aluminum or ABS plastic in its place in most cases.
I’m not saying it isn’t useful, but it isn’t a thing I’d put a ton of effort into if you aren’t already pushing the limits of your team’s capability. Replacing a part with a CF version won’t make a bad design suddenly become good.
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My team used carbon fiber for our climber this past year. It can make a cool element to a robot when you play into its (tensile) strengths! But in the case of using CF structurally I agree with the people who have replied to this before me is probably not the best idea for the vast majority of situations.
I don’t agree with these statements. To begin, drilling a hole in a carbon fiber plate is no more difficult than drilling a hole in a fiberglass plate. Which is fairly easy. Certainly easier than drilling steel.
The safety requirements of fabricating in carbon have repeatedly been over-started here. Carbon fiber isn’t a boogey man that people should be afraid of or avoid.
Controlling particulate is important when machining carbon. But it’s actually very easy to do. A water or lubricant mist, a shopvac (with filter) or other methods will make it quite safe if proper care is taken.
Like anything else, knowing how to do it is important. Doing it wrong will get you in trouble. But carbon fiber is not a scary thing.
I don’t think I’ve seen it mentioned, but make sure to wear proper gloves when handling cut CF/ particulate. Carbon Fiber splinters are quite nasty.
Maybe it’s just the composites we work with at my Uni since we create our own instead of just buying. I am still new to the material and thats what some of the upperclassmen here have told me so maybe they’re just over exaggerating. Sorry if what I said is wrong
We have used CF on our robots for the past 3 years for various reasons, but mostly for stiffening of structure that is higher up on the bot.
Our shooter pivot plate in this pic of our 2024 robot:
Our conveyor/shooter vertical structural frame of our 2022 robot:
In both cases, we used prepreg carbon sheet stock and cut it on a waterjet.
The result was several pounds lighter than aluminum sheet (and stiffer)
Another note: we also use a decent amount of titanium sheet on the robots, in those photos above most of the brackets are titanium (also waterjet — titanium is very hard to drill through)
I don’t know that they’ve been overstated; maybe other users have been vague but the dangers are 100% real.
Here are some credentialled resources that include in-text citations:
[1] “The adverse toxic hazard as defined by the Safety Data Sheet (SDS) is classified as an acute
toxic substance with no known cause of disease but carbon dust and fly can cause transient
skin irritation. This effect is compounded by the curing agents used for fiber sizing, in which
case human contact should be limited by the use of proper hazard controls. Pitch-based fiber
has demonstrated in some studies to be associated with an increased risk of skin cancer,
although evidence is weak (Ahmad 2009, OSHA 1999).” (https://ntrs.nasa.gov/api/citations/20150012180/downloads/20150012180.pdf)
[2] “Skin irritation has been observed among workers in
carbon fiber manufacturing and processing plants. A study
at such a Russian facility indicated that 24% of the workers
had occupational dermatitis characterized by inflammatory
eruptions of the skin (34).” (https://apps.dtic.mil/sti/tr/pdf/ADA194835.pdf)
[3] “Pitch-based carbon fibers may be associated with an increased risk of skin cancer, although the evidence is weak. PAN-based carbon fibers did not cause tumors when the same test was conducted. Standard mutagenicity tests conducted on PAN-based carbon fibers were negative (…) The principal hazards of carbon-fiber handling are mechanical irritation and abrasion similar to that of glass fibers. Skin rashes are common and reportedly more severe than from glass fibers.” (https://www.osha.gov/otm/section-3-health-hazards/chapter-1)
I would rather that teams be overly cautious regarding the risks involved than overly lax and to potentially put themselves in positions where students are risking their health, including potentially lifelong lung problems and increase risk of skin cancer. I especially don’t like the phrasing in your post which I feel implies that teams should take the dangers of carbon fiber less seriously, or emphasize them less. This is a thread about fabricating carbon fiber. The risks related to carbon fiber fabrication (cutting, drilling, and routing) are absolutely relevant and, if anything, routinely understated.
(Currently attending a college in the US, it has been less than 24 hours since I saw someone demonstrate cutting fiberglass tube with a hacksaw in a moderately-crowded room, without anyone in said room full of engineering majors knowing whether or not it was safe. I don’t believe it was.)
I’m not saying you can’t fabricate carbon fiber safely, but I don’t think anyone here is overstating the dangers of cutting carbon fiber. The common thread between all of the sources I cited above is that we don’t know with confidence what the long term effects of extended exposure to carbon fiber particulate are. Until then I don’t think anyone should be claiming that carbon fiber is entirely safe to fabricate, or waiving concerns people have with fabricating CF parts in-house.
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I know you mean actually carbon fiber sheets, but just wanted to add that our team has used carbon fiber 3dp filament before to print things, and they have ended up being pretty strong!
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Oh for Pete’s sake. This is exactly what I’m talking about.
PLEASE reread my post. Don’t create a straw man argument. If you take proper precautions, carbon fiber fabricating is considered safe.
Use methods to reduce dust through wetting, and a dust collecting system with a quality filter.
FYI, fiberglass is a very well understood material. Cutting a piece with a hacksaw in a room presents very little risk to anyone, other than getting some very itchy hands.
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I read your post in full; I also pointed out exactly where I took issue with it. If you could point out the lines where you believe I’m strawmanning, I would greatly appreciate that.
For clarity, disagree with the sentiment in this exact line in your original post, which I quoted at the beginning of my post.
I believe carbon fiber is absolutely something to be wary of. I cited sources to my claim that the scientific community does not know with confidence what the long term effects of extended exposure to carbon fiber particulate are. I don’t think the safety requirements of fabricating in carbon have repeatedly been over-started in this thread. I think saying this devalues posts with great advice about the risks of fabricating carbon fiber. I think this was all made pretty clear in my original post.
I also made sure to acknowledge that you can fabricate carbon safely at the beginning of the last paragraph. My alumni team has done so, and did so while I was on the team. We used a wetsaw with dust-collection, I believe through a HEPA filter. Considering the second line of your reply, I trust that you likewise read my post in full.
To your point about cutting fiberglass, most sources I could find recommended wearing a half-face respirator while cutting it, even by hand. Here’s one of many: (Fiberglass Fact Sheet)
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I’m going to directly quote your post here.
Do you trust a bunch of high schoolers without a mentor who knows carbon fiber or fiberglass handling to do it correctly?
If you do, then you are a much bolder man than I am! Particularly given the second half of that statement, repeated here for emphasis:
So, I trust that you are going to give more guidance on how not to do it wrong, then? Or are you going to let the rest of the Internet teach us, possibly incorrectly?
All you’re saying is “wet it down and collect the dust”. Wet with what? What if we don’t have a dust collecting system? What if we need to handle near the cut/drilled edge? What about hand-drilling or hand-cutting? Are we talking about prepreg or laying up the team’s own material? What’s the recommended PPE? (I can tell you what some pros use–Tyvek suits, nitrile gloves, safety glasses/googles and mask or higher protection for the face–from seeing them work in a nearby area. Heck, my crew of aluminum workers got a short CF safety briefing when those guys moved in across the aisle from us, just so we wouldn’t freak out/mess ourselves up.)
Also, I would characterize “itchy hands” as “undesirable outcome” or “mildly hazardous”. Sounds like someone should wear gloves when doing that, no?
I would rather students reading this be properly educated in “how to do this safely” than a handwavey “it’s safe if you do it right” with no further details. I don’t know for sure how to work with CF safely; I know others do, and would appreciate those others posting their knowledge.
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what are the problem you are tryin solve with cf?
You do not need to fear the cleaning agent chlorine trifluoride.
(from the wonderful webcomic Freefall)
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As far as carbon cutting goes, the inhalation risk I’d imagine is similar to that of lead-based solder vapors as well as spraypaint / powder coating paint. These are a good characterization of long term injury risks. Meanwhile, table saws and miter saws are short term injury risks.
I wouldn’t leave a student alone to do any of these tasks without initial training and ongoing oversight. But once the proper training is in place, none of these are less safe than the other.
Though with all my racing drone experience I can attest to the pain and annoyance of carbon splinters in the hands.
Now I wouldn’t go using carbon fiber on a deep sea submersible, but handling around the robot shop with the proper tools and safety precautions I don’t have too much of concern with.
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