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  1. #1
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    Anodizing Calipers and Master Cylinders

    Just something I am considering with some Hopes for that custom stealth look, I saw a post recently where someonen was having it done but there was no follow up. Has anyone done it and if so did they have any problems?

  2. #2
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    Can't imagine that it worked, hence they did not post back. If you know anything about anodising, you'll appreciate that it 'adds' material to the surface. This would therefore mean that the pistons would no longer fit onto the bores, and new O Rings would need to be measured and fitted. Also, the fittings will likely no longer fit into the threads (would likely need to be chased).
    If everything was masked off/plugged properly - meaning only coating on superficial areas then yes, it could of course be done. If you really want a new colour, have you considered just painting them?

    Brad

  3. #3
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    Bradders, thanks for te response, I know the process involves forming a layer of oxidation on the surface and dying it, and that it adds a layer to all surfaces, hence as you mention the possible issues, but i thought the thickness of the added layer was only microns thick, and was not sure that the machining tolerances would be that tight.

    Had not really considered painting, but guess it could be an option, the only concern would be i guess undercoating with an etch primer first, but also finding a paint resistant to the DOT fluid.

  4. #4
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    Hi Mark,
    From my personal experience of anodising (through my work), it adds a layer 50 microns thick (0.05mm) to each surface. Therefore when you have 2 mating parts, you need to allow 0.1mm for the anodising tolerance.

    In my line of work (subsea machined components) this is quite a large tolerance, and would definitely cause problems if it was not taken into consideration. Particularly because of the high pressures that are involved with the products that we make. A bikes brake system is at very low pressure. However hydraulics being hydraulics will always try to exploit any defects in the system (causing leaks).

    The problem you will have if you anodise will be that the pistons may not fit into the bores/and or they will not retract properly.

    I too had considered pimping my brakes (old Hope Mini), but it is fraught with too many problems in my opinion. I think that painting would be best, I wouldn't worry too much about finding a paint that will stand up to Dot fluid - how many times have you got it on your frame/handlebars?

    Brad

  5. #5
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    i am the one whos been lookin in to it and after some long checking,it will work as the place where i will be going do brake calipers anyway.watch this space

  6. #6
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    for the type of anodizing that would likely be used (type II sulfuric), I doubt that there will be any problems in terms of interference, parts binding etc.

    per our friend wikipedia:
    Sulfuric acid is the most widely used solution to produce anodized coating. Coatings of moderate thickness 1.8 μm to 25 μm (0.00007" to 0.001")[7] are known as Type II, as named by MIL-A-8625

    even on the thick end of the spectrum, .001" on each part is not that significant. general machining tolerances are likely in the +/- .005" anyway.

    also consider that the pistons, master cylinders, etc, are sealed with rubber seals that are made to adapt to varying tolerances.

    my bet is that bradders' business requires a significantly narrower tolerance than normal applications due to the environment. also, I bet that hard anodizing is used more often on his applications, which requires a thicker coating.

    painting would be worse than anodizing in terms of maintaining tolerances. way thicker and leaves open the possibility of chipping. plus the matter that some paints will not stand up to heat (which will inevitably happen on brakes).

    I say ask hope and see what they say about it. if the tolerances are really that tight, then just leave them

  7. #7
    discombobulated SuperModerator
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    When we anodized 'precision ' parts, tight surfaces were masked . Some sort of tape or wax coating IIRC..
    Same went for 'precision' chrome, bearing surfaces were masked by the vendor.
    CDT

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