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  1. #26
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    Quote Originally Posted by PissedOffCil
    Very nice!
    I would probably add more venting to the fins though.
    Thanks

    Keep in mind that these are for a Hope M4, so there is actually more heat sink than the Ice-Tech as far as I can guesstimate.

    Anyhow, keep in mind this is an experiment, so we will have to wait for the facts till tomorrow.
    Then I will make some thermal images with regular pads and with the Carbon pads.
    Once we have the thermal images, the rest is a piece of cake to adjust for.


    Magura

  2. #27
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    Dayum. You have mad fabrication Kung Fu, my friend!

    My only critique might be to make a more defined 'pad' area. If the pads wear around the rotor, you wouldn't want the two pads to tough above the rotor, making a perfect little U where the rotor goes. If the pads touch, then you won't be able to apply pressure from the caliper. I've seen this happen with brakes that were not adjusted correctly, and the brake caliper was too high in relation to the rotor.

    Are those Hope M4s top loading like Shimano? My 2004 Mono Minis are not. You have to drop the wheel out to remove the pads out of the bottom of the caliper. It's going to make for a difficult heat sink shape, I'm sure.

    This is all my 'skillz' could muster with a hacksaw, a vise, a dremel and a couple hand files:





    I haven't determined the final shape of whatever sicks out of the caliper yet. I'm waiting to see what computer heat sink parts I can get my hands on.

    This is just a quick and dirty trial.I'm worried that the copper backing plate is too thin, and wont' be a big enough 'pipe' to wick heat up to the heat sink. OTOH, something is better than nothing. The question is, whether it makes a big enough difference to be worth it.

    *edit*

    I was thinking of something like these little guys:

    Last edited by pimpbot; 04-22-2011 at 12:08 PM.

  3. #28
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    Quote Originally Posted by pimpbot
    Dayum. You have mad fabrication Kung Fu, my friend!

    My only critique might be to make a more defined 'pad' area. If the pads wear around the rotor, you wouldn't want the two pads to tough above the rotor, making a perfect little U where the rotor goes. If the pads touch, then you won't be able to apply pressure from the caliper. I've seen this happen with brakes that were not adjusted correctly, and the brake caliper was too high in relation to the rotor.

    This is all my 'skillz' could muster"


    I haven't determined the final shape of whatever sicks out of the caliper yet. I'm waiting to see what computer heat sink parts I can get my hands on.

    This is just a quick and dirty trial.I'm worried that the copper backing plate is too thin, and wont' be a big enough 'pipe' to wick heat up to the heat sink.
    Thanks.
    As I wrote earlier, this is just a rough prototype, simply to make a proof of concept, and to get a ballpark figure regarding the effect. The brake area will sure be more "defined" on a later model.
    This is as quick and dirty as possible, simply to get out and collect some real world data, to replace our guesstimates with

    If your system works is easy to tell. Go down a hill and when you are done braking at the bottom, just check if the copper sheet is warm/hot.
    If so, it sure works, next step is to tell how well it works
    There is nothing wrong with quick and dirty style prototypes, in fact I think it's the only way for one man bands like us to get anywhere.

    Magura

  4. #29
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    Yeah....

    Quote Originally Posted by Mr.Magura
    Thanks.
    As I wrote earlier, this is just a rough prototype, simply to make a proof of concept, and to get a ballpark figure regarding the effect. The brake area will sure be more "defined" on a later model.
    This is as quick and dirty as possible, simply to get out and collect some real world data, to replace our guesstimates with

    If your system works is easy to tell. Go down a hill and when you are done braking at the bottom, just check if the copper sheet is warm/hot.
    If so, it sure works, next step is to tell how well it works
    There is nothing wrong with quick and dirty style prototypes, in fact I think it's the only way for one man bands like us to get anywhere.

    Magura
    It all makes me want to read up on how heat conducts through solids... how the formula works. I know for electricity, its all about the surface area of the cross section of the conductor (and naturally, the conductor's material). I imagine heat conducts in a similar way.... and also, the temperature differential between the heat source and the heat sink.

  5. #30
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    Quote Originally Posted by pimpbot
    It all makes me want to read up on how heat conducts through solids... how the formula works. I know for electricity, its all about the surface area of the cross section of the conductor (and naturally, the conductor's material). I imagine heat conducts in a similar way.... and also, the temperature differential between the heat source and the heat sink.
    It works exactly like electricity, where you have conductivity, resistance, cross section, and so forth.

    In your case, you can measure the difference in temperature between the heat sink and the brake pad, and you will know the thermal resistance of the heat sink/brake pad interface.

    My one piece brake pad-heat sink is a lot more simple to get some numbers from, as all I have to do is to make a couple of thermal images, and compare.
    Another fancy property of the Carbenix carbon, is that the heat conductivity is directional, so I have made it to transfer heat in the direction between the heat sink and the pad, and only let about 25% go in direction of the caliper. That in itself ought to make a difference.
    Now the big question to me is how well the Carbenix works with steel rotors. I have never tried that configuration before. My hope is that it will rub off on the rotor, and effectively become a carbon/carbon brake interface.

    In your case you could actually also get away with just measuring the temperature of the caliper, as that is the aim of this project, to keep the temperature down. All you really have to do is to figure how much you need to lower the caliper temperature, to get a significant improvement over regular pads with no heat sink.


    Magura

  6. #31
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    awesome thread...been fun to read all the things you guys are doing, especially with the machined pads...

    keep up the innovation...
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  7. #32
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    Really interesting thread! I hope You Know Who doesn't show up...

    By the way, at the risk of sounding like a neanderthal, why do you suppose it is that downhillers and other brake fluid boilers stick with hydro brakes when mechanical disks are immune to this form of power loss? Honest question.
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  8. #33
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    @Buddhak

    My guess it takes less finger pressure/hand effort to activate hydros than mechs

  9. #34
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    Quote Originally Posted by buddhak
    Really interesting thread! I hope You Know Who doesn't show up...

    By the way, at the risk of sounding like a neanderthal, why do you suppose it is that downhillers and other brake fluid boilers stick with hydro brakes when mechanical disks are immune to this form of power loss? Honest question.
    My reasoning behind hydraulics, is better modulation, and better finger force to brake power ratio.
    At some point the amount of force it takes to brake, becomes an issue on a long downhill section.

    Magura

  10. #35
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    Quote Originally Posted by pimpbot
    *edit*

    I was thinking of something like these little guys:

    Those little heat sinks look good for the purpose, but the adhesive backing needs to go, as it will not like the temperatures you will expose it to.
    Epoxy would be the ticket, and is cheap as well.


    Magura

  11. #36
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    Time for a test ride.

    I had to wait till the Loctite on the rotor bolts cured (floating rotor, DIY as well), but now it's time for a test ride.

    Magura

  12. #37
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    Just returned from the initial test ride.

    In short: This kicks a$$ BIG TIME!

    Loads of modulation, more bite than ever, caliper around the temperature of a grave diggers butt, heat getting transferred to the heat sinks, carbon transfers nicely to the rotor.

    Whats not to like?

    Some more scientific test later today, as it's too hot for riding hard enough to heat up the whole system (if possible).

    Big thanks to Pimpbot for pointing my thoughts in this direction.
    I wonder why it has never occurred to me before to use Carbenix for bike brake pads, now that I've used it before and had it in stock.


    Magura

  13. #38
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    They're not

    Quote Originally Posted by buddhak
    Really interesting thread! I hope You Know Who doesn't show up...

    By the way, at the risk of sounding like a neanderthal, why do you suppose it is that downhillers and other brake fluid boilers stick with hydro brakes when mechanical disks are immune to this form of power loss? Honest question.
    They don't have fluid to boil, but when the pads get hot enough, they offgas and get slick also. Mechs stop working when they overhead just like hydros do. THey don't have fluid to go into vapor lock, but the pads and rotors still get hot.

    I've had BB7s on a bike before, and overheated them to the point where they stop working.

    Plus, nobody really makes a really big pad mechanical... like the equivalent of a 4 or 6 pot big brake. At least, as far as I know.



    Dang! Gatorbrake 8 pot brake!


  14. #39
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    Too hot to ride?

    Quote Originally Posted by Mr.Magura
    Just returned from the initial test ride.

    In short: This kicks a$$ BIG TIME!

    Loads of modulation, more bite than ever, caliper around the temperature of a grave diggers butt, heat getting transferred to the heat sinks, carbon transfers nicely to the rotor.

    Whats not to like?

    Some more scientific test later today, as it's too hot for riding hard enough to heat up the whole system (if possible).

    Big thanks to Pimpbot for pointing my thoughts in this direction.
    I wonder why it has never occurred to me before to use Carbenix for bike brake pads, now that I've used it before and had it in stock.


    Magura
    Is that even possible in Denmark? When I was there, it once got to 28C, but I was told that was really unusual. It's not unusual to ride in 38C weather here in California.

    It probably did occur to somebody, but like you said; that Carbenix stuff is crazy expensive. It's awesome you have access to little scraps to play with.

    Hey, can you post picks of the installed final result? I would love to see them. *edit* Okay, you did post pics. For some reason, my browser didn't load it the first time.

    Last edited by pimpbot; 04-23-2011 at 07:42 AM.

  15. #40
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    Quote Originally Posted by pimpbot
    Is that even possible in Denmark? When I was there, it once got to 28C, but I was told that was really unusual. It's not unusual to ride in 38C weather here in California.

    It probably did occur to somebody, but like you said; that Carbenix stuff is crazy expensive. It's awesome you have access to little scraps to play with.

    Hey, can you post picks of the installed final result? I would love to see them. *edit* Okay, you did post pics. For some reason, my browser didn't load it the first time.
    It's like 24-25C and sunny now, but keep in mind that we are not used to heat at all. Back when I lived in eastern Europe, I was happily riding in 30C or more, but there it was a usual summer temperature.

    I have more than 100kg of Cabenix in stock, so if you want, you can have a piece to play around with.

    I just wondered why I didn't think of it before myself, as cost is not really a factor, having already paid for the stuff in the first place.

    As I wrote earlier, once it gets colder, I'll put my thermal imager in the hands of the Mrs., so we can get some facts on the table.


    Magura

  16. #41
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    So, finally the temperature got under 20C and the sun is setting.

    The two images are thermal images, made with my Fluke Tix Thermal imager.

    The temperature points are corrected for emission factor, so are fairly accurate.

    As you can see, the pad temperature is almost half on the carbon pad, of what it is on the sintered pad. Half, as in half of the temperature rise above ambient.
    The rest is self explanatory I guess, just look at the colors.

    Magura

  17. #42
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    I have done something similar with the IHS of CPU's. Making the surface of the CPU and heatsink flat results in lower operating temperatures.

    Lapping the back of the brake pad and copper plate could work well. The use of a thermal epoxy is only to make to uneven surfaces as flat as possible thus aiding heat transfer.


    Taken from a thread of mine:

    "What you need to lap, is a series of increasing fine sand papers and something extremely flat (a sheet of glass is good). You're looking to go from something like 400, 600, 800, 1200, and finally 1600 grade papers. You can use even finer grades as upto 2500 and beyond as they're fairly easy to get hold of and even metal polish for that final shine but the benefits for cooling are minimal if anything. Wet and dry paper is better as the water acts as a lubricant and aids with the sanding process."

  18. #43
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    Never mind, post deleted.


    Magura

  19. #44
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    Quote Originally Posted by pimpbot
    It probably did occur to somebody, but like you said; that Carbenix stuff is crazy expensive. It's awesome you have access to little scraps to play with.
    If you'd like, I'll send you a piece of Carbenix, big enough for a set of pads for front and rear.

    Then you can make the style of heat sinks / pads as you see fit.


    Magura

  20. #45
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    Reading this tread with great interest since I've been thinking of ways to better cool my brakes. So I found a pic of the Shimano pads and it doesn't appear that there is much contact area between the pad and the heat sink. I'm wondering how much of the addition cooling from the new Shimano brakes have to do with their new rotor design.

    Perhaps an easier approach would be to design some type of ducting/fan that would improve air flow, but without throwing excessive dirt at the caliper.
    Attached Thumbnails Attached Thumbnails Homebrew Heat Sink?-shimano_xtr_m980_brake_pads_600.jpg  


  21. #46
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    Would you mind sharing with us how you manufactured the carbenix pads?

  22. #47
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    Quote Originally Posted by BitterDave
    Reading this tread with great interest since I've been thinking of ways to better cool my brakes. So I found a pic of the Shimano pads and it doesn't appear that there is much contact area between the pad and the heat sink. I'm wondering how much of the addition cooling from the new Shimano brakes have to do with their new rotor design
    The heatsink material is sandwiched between the pad and backing, giving excellent heat transfer and isolating the caliper further from the heat source (this way around the steel backing would heat/cool slower against the caliper). I'd probably go with more surface area on the fins as they seem a bit chunky (too cautiously biased towards sturdiness), but otherwise it looks like quite an effective setup.

  23. #48
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    Looks to me...

    Quote Originally Posted by BitterDave
    Reading this tread with great interest since I've been thinking of ways to better cool my brakes. So I found a pic of the Shimano pads and it doesn't appear that there is much contact area between the pad and the heat sink. I'm wondering how much of the addition cooling from the new Shimano brakes have to do with their new rotor design.

    Perhaps an easier approach would be to design some type of ducting/fan that would improve air flow, but without throwing excessive dirt at the caliper.
    ... like the heat sink is one piece to the brake pad, with a plate behind it.

    I'm just not sure the heat pipe cross section is that big between the pad and exposed heat sink.

    Heh... funny about heat isolation on non-finned brake pads. My XTR pads have copper backs, while the Hone pads I got with a caliper are made of steel. They are basically interchangeable pads. Some of the XTR pads for my generation brakes are Ti, which is a horrible conductor of heat. I think they were just thinking of the weight reduction.


    Quote Originally Posted by Mr.Magura
    If you'd like, I'll send you a piece of Carbenix, big enough for a set of pads for front and rear.

    Then you can make the style of heat sinks / pads as you see fit.


    Magura

    Sounds great. I might take you up on that. I wonder how you shape it, without the benefit of machining tools, CNC, etc. I only have hand tools at my disposal. Also, what is the MSDS on that stuff. I'd imagine you rreeeaaally don't want to breathe that dust.

  24. #49
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    Quote Originally Posted by Mr.Magura
    Time for a test ride.

    I had to wait till the Loctite on the rotor bolts cured (floating rotor, DIY as well), but now it's time for a test ride.

    Magura
    Anybody else find it funny that Mr. Magura is riding on Hope brakes?
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  25. #50
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    Quote Originally Posted by pimpbot
    ... like the heat sink is one piece to the brake pad, with a plate behind it.

    I'm just not sure the heat pipe cross section is that big between the pad and exposed heat sink.

    Heh... funny about heat isolation on non-finned brake pads. My XTR pads have copper backs, while the Hone pads I got with a caliper are made of steel. They are basically interchangeable pads. Some of the XTR pads for my generation brakes are Ti, which is a horrible conductor of heat. I think they were just thinking of the weight reduction.
    Thanks for the clarification Cubits and Pimpbot. So when the brake pads wear out, you toss the heat sinks too?

    Is it difficult to machine Carbenix? Is the dust abrasive?

    Are the finned Carbenix brake pads necessary? You have (I assume) a friction material that will cause your rotors to glow orange before the performance falls off. If that's the case, then the extra cooling really isn't necessary, except to prevent the brake fluid from boiling. In auto racing, that is done by having notched pistons to minimize the contact area with the pads and the use of a thin titanium plate.

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