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  1. #1
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    Material for brake rotors

    Hi guys,

    i've bin fiddling around with having some new rotors cut for me by one of my suppliers who has a laser cutter, however the stainless steels i've tried haven't exactly had the strength for the job an i got a couple of pretzled rotors lying on my desk at the mo hehe. Anyone out there got an idea of what material the rotors are cut from?

  2. #2
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    Got pics?

  3. #3
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    Some companies use different alloys of aluminum for their rotors, but i can only assume that without proper heat treating and tempering, thet they would do the same, not to mention you can only use certain pad compounds with them...sintered pads will EAT alu. rotors alive! The "normal" material that most use is in fact stainless steel (not sure of the alloy though) but I'm sure that they are tempered or heat treated in some manner in order to make stronger. On a side note...can you post a pic of these crumpled rotors? Aside from wanting to see them, i bet you could get some good feedback on the design...maybe the "arms" of the rotor are not beefy enough or something. Cheers!

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    i don't know about the heat treatment mostly because i know from experience stainless warps like a b*tch when you really heat it. I've been looking at using a duplex stainless however my supplier doesn't stock it which is a bit of a kak one. Spose the joy of laser cutting means that i can cut pre tempered/heat treated steel but which grade is the big question. I did run some FEM analysis on the design however that doesn't look too much at the 3d picture, more the 2d plane so the results always came back positive. Starting to work with a more powerful package so hopefully i'll be able to get some decent results before i risk my neck again. The FEM model is the new design with the arms 50% bigger than the one in the photo
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  5. #5
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    watch this 1:40-2:00 if you want to consider aluminum. i love top gear

    Anyways I'm no engineer but where do you cut first? My idea is to cut out the center first.

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    Forget aluminum. I would go for 316 stainless first. Most finished rotors are 2mm (.078") thick or just under so you will have to buy it thicker than you want and have it blanchard ground flat and to size. This will take care of removing the stress from the materials skin and make it dead flat.

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    problem with 316 and 304 is that they arent the strongest materials around, i've been onto my material supplier gonna try get a nice piece of duplex steel out of them which should have the strength i need, also won't warp under heating. yea ali is the last material i'd go for jus way too weak and prone to cracking and sudden failure!!! i've made rotors for quads before but they nice and beefy with existing hubs so they haven't had any issues will see how this latest design works out with the duplex nice thing is that it hasn't cost me anything so far so trial and error should work out alright, forgot to mention earlier that stress model was calculated by working out the forces braking from 40mph to 15mph in 2sec (using only the front brake) then multiplying that by 2 and converting it to a torque, might be a bit of overkill but i don't want the disc to pretzel when i actually do it

  8. #8
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    I had some brake rotors made for me by a guy i know.
    They work freakin sweet...better than my std avids infact.

    Will post up a coupla pics for ya.

    Not too sure what kinda stainless he used but i will send him an email to find out for ya.


    Patience is not a virtue, its a weakness!

  9. #9
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    Good thread. That pretzel is fantastic
    Quote Originally Posted by saturnine
    that's the stupidest idea this side of pinkbike.

  10. #10
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    I was just looking on Galfer's website, and they use 420 or 410 stainless for their rotors...and theirs are legit. Just thought i would throw some more into the pot...

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    you should try metal matrix composites, a couple of the professors at my college own a side engineering business and they've been playing around with them for motorcycle and truck brakes. I saw one and the material looks friggin sweet and its crazy light.
    I lubed my disc brakes because they squeaked.
    Man was that fun to work out

  12. #12
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    My buddy and I use 410 stainless for our rotors.

    We found that it was difficult to find full hard material, so we ended up laser cutting from softer material and heat treating to full hard when done. As you noted, it warps quite a bit if you don't fixture properly.

    Since we purposely bought thicker than required material to start with, we were able to double-disc grind after heat treatment down to size which took care of any warping issues during heat-treat.

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    Quote Originally Posted by AnGeL_DusT
    i don't know about the heat treatment mostly because i know from experience stainless warps like a b*tch when you really heat it. I've been looking at using a duplex stainless however my supplier doesn't stock it which is a bit of a kak one. Spose the joy of laser cutting means that i can cut pre tempered/heat treated steel but which grade is the big question. I did run some FEM analysis on the design however that doesn't look too much at the 3d picture, more the 2d plane so the results always came back positive. Starting to work with a more powerful package so hopefully i'll be able to get some decent results before i risk my neck again. The FEM model is the new design with the arms 50% bigger than the one in the photo

    try superduplex or 17-4 ph, the 17-4 ph is one of the strongest stainless you will find except for martensitic knife/tool types which are´nt really stainless anyway.
    Quote Originally Posted by Curmy
    Carbon is a fad.
    Quote Originally Posted by robicycle
    Just lube your ass with asscream and ride for how long you want.

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    Quote Originally Posted by courtjester_78
    I was just looking on Galfer's website, and they use 420 or 410 stainless for their rotors...and theirs are legit. Just thought i would throw some more into the pot...
    Forgot to mention, that Hayes rotors I have in my posession are 410 stainless.

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    nice thanks guys will get a couple made up an see how they operate

  16. #16
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    420 or more readily available 416 work well.

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    Quote Originally Posted by vk45de
    watch this 1:40-2:00 if you want to consider aluminum. i love top gear

    Anyways I'm no engineer but where do you cut first? My idea is to cut out the center first.
    OMG that was too damn funny!

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    Quote Originally Posted by cort
    OMG that was too damn funny!
    No kidding, had to watch part 2 afterwards. Too funny ROFLOL
    Quote Originally Posted by saturnine
    that's the stupidest idea this side of pinkbike.

  19. #19
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    OK...

    The rotors that were made from me were made from SAF2205.
    It has a high tensile strength i am told so that is the reason Chris used that for rotors.
    Patience is not a virtue, its a weakness!

  20. #20
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    # Sandvik SANMAC SAF 2205™ is a duplex stainless steel (austenitic-ferritic). It is characterized by:high resistance to stress corrosion cracking in chloride-bearing environments
    # high resistance to stress corrosion cracking in environments containing hydrogen sulphide
    # high resistance to general corrosion, pitting and crevice corrosion
    # high mechanical strength – roughly twice the proof strength of austenitic stainless steels excellent machinability
    # good hot-working properties
    # high resistance to erosion corrosion and corrosion fatigue
    # physical properties that offer design advantages
    # good weldability

    Information provided by Sandvik

    UNS S31803, S32205; EN 1.4462

    http://www.matweb.com/search/DataShe...2f1f577&ckck=1
    Quote Originally Posted by Curmy
    Carbon is a fad.
    Quote Originally Posted by robicycle
    Just lube your ass with asscream and ride for how long you want.

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