Me and some people on our team are looking into using carbon fiber (hopefully) in the near future. What grade of carbon fiber do you recommend we get. I’m looking into getting a roll and seeing the price difference I don’t want to overspend on something we don’t need.
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There’s a correct answer right within that statement.
“we don’t need”.
If you’re going to use carbon fiber, buy pre-made pieces (rods, hockey sticks, etc.) rather than making your own. If you can’t find something in the right shape, pre-preg carbon fiber is going to be your friend. But for the vast majority of FRCFIRST Robotics Competition teams, see the response to :
Factor to consider: Making spare parts.
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What is your reasoning to support this? What advantages do you think you will get? Do you know how to design in a way that uses carbon fiber in an advantageous way? Are you prepared to deal with the hazards? Are you wanting to use it for “the cool factor”?
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Where might one buy these?
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For the hockey sticks, ask the Canadian teams. (Or your local hockey store.)
For the rods–actually, I should have put “tubes”, it’s been a long day. McMaster has some (and rods), but you’ll have to ask someone other than me for the rest. I don’t deal with composites much if at all (and usually it’s a FRP electrical box if I’m working with them).
We use these guys.
Bonus - they come in some very fun shapes. We used hex tube in 2019, and we used some leftover hex and some octagonal tubing this season. Benefit of those is they shouldn’t spin in the printed part we attached them to, whereas a round tube will.
Also to add onto the otherwise already sound logic responses by other members of this community, I will say, if you REALLY want to use a carbon fiber based material, they make Nylon X thats just as durable and at a reasonable price.
Be aware your printer needs to be able to print the material as the requirements are extensive.
Our team uses:
for parts that need to be lightweight, but also handle a lot of abuse.
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Canadian here!
If you have a local hockey league/club, talk to them about possibly getting some broken hockey sticks donated. I haven’t needed or tried to source any recently, but this is how we used to get them when I was with 2386. You’d be amazed just how many sticks get broken on the ice and then thrown away as a result.
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Or for the hockey sticks check the dumpster behind a rink …
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If you’re not using a standard shape like tubes etc. Then you can 3d print the molds and mold them yourself https://youtu.be/25PmqM24HEk?si=Xm0FVtHIMI0qsZw4
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We switched to Clearwater Composites last season. They have the same 15% educational discount as RockWest but are somewhat more local in Minnesota, and their prices seem to be like 10% cheaper.
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Looked at them, but for non-round tubes the size options are much different. Great place for the smaller stuff for sure! Did the tubes look and feel the same as RW?
We’ve only used the round. They’re where we bought the huge round tubes for our 2023 bot. They seemed just an woven and shiny and rigid as the woven shiny rigid tubes from RockWest.
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Warning, could be terrible advise because I am not an expert.
The main reason I had no complaints pulling the trigger on CF this year - it was cheaper and lighter than aluminum.
We designed our CF arm around 500mm lengths because, in my experience, you get a significant price break there. My best guess is that this has to do with the drone market.
$15 / 500mm CF tube
vs
$20+ / ft for aluminum tube
(yes I know it feels ridiculous to link McMaster as the price comparison to buy aluminum, but we have some purchasing difficulties and haven’t found a good local metal supplier)
Strength was not an issue for us. The arm took a couple significant hits including one where it turned out to be stronger than the max tube on our elevator.
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We use mcmaster for tubes and rods
Nylon X isn’t anything close continuous carbon fiber. NylonX has a rated tensile modulus of 6 GPa and an ultimate tensile strength of 100 MPa while continuous fibers can have youngs modulus and ultimate tensile strength of over an order of magnitude higher.
I’m not saying that Nylon X is bad, but, it is not remotely comparable to actual carbon fiber in applications that would call for using carbon fiber.
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A couple good companies for getting carbon fiber (or other composite) stock are rockwest, dragonplate, goodwinds, and mcmaster, among others. Rockwest also has a great page going over how to properly bond prep and select adhesives if you chose to bond your structure. Also keep a look out for clearance / offcut sections on these websites, sometimes they will sell odd lengths of tubing much cheaper than you could normally get.
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