Technical & Reference Section > Tech and Restoration
Adventures in Anodising
Avro:
Before:
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After:
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Result! Can not help but feel well chuffed *giggles*
Decals as always by Delcals.
griff:
Brilliant result :4_17_5:
chrisv39:
It's threads like these why I love RAD. I love to see people restoring their bikes themselves rather than spending mega bucks on nos parts and tah dah here's another ridiculously expensive build I've bolted together.
Great work mate :daumenhoch:
dancetothedrummersbeat:
^ exactly. I love it! Well done!
Avro:
Given that I have to move in 8 weeks time, to where I do not know at the moment, I thought I had better get on with a few more adventures in anodising before starting to pack up. The brake calipers were next up. These were subject to a previous attempt which turned out rather well although the anodised layer was too thin as it turned out. That said, I was very much encouraged by the results. The beauty of these experiments is that they are repeatable given that one can strip the part and start over. I finished the brake calipers as discussed before and moved on to the anodising process proper.
I decided to bolt up the connection using aluminium nuts and bolts (greenhouse fittings as it happens). This proved to be a boon as you can use the wire as a handle to dip the parts and no real use for rubber gloves (a disadvantage if you are that way inclined I guess). As it turned out the bolt up connection was far superior to wrapping the wire, no matter how hard you try to crimp the connection tight. Yes, there are small areas where no anodising takes place (you can control this) but the wire is not consumed at all so no danger of erosion.
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I have reread this thread, and the questions asked, and realise some explanation is required on certain points. Polishing before putting the item through the anodising process is crucial. When I refer to rubbing the parts down with ever finer papers that is polishing although not to a super fine grade. The brake calipers were rubbed down, polished, to a finer grade than the pedal cages with paste but only because they demanded it given their profile. Furthermore, the parts I am using are not immaculate, they have scars and imperfections, in some instances they are well used. How do I cope with those? How much material am I prepared to sacrifice to achieve a given finish? The truth is I do not know; although I do know that the better the finish going into the tank the better the result coming out. The variable is the condition of the part and how far you go. I have learnt that much and to err on the side of caution. Although the anodising process is repeatable the preparation is not. When I said 'I have not even polished them yet' I meant that I had not given them a wax polish.
I had planned to anodise some larger items but only if experiments thus far had proved successful. I have a set of cranks and a chain wheel that are currently silver, the cranks for my Bobby Encinas fun bike and the chain wheel for my Laserlite. Those projects will have to go on hold until I move. Both items need a bigger tank, which would be a waste to set up now when it would have to be disposed of shortly after. Incidently I had an interesting parcel delivered a few weeks ago....6 litres of 96% Sulphuric acid! I am still amazed you can order such stuff mail order!
Back to the brake calipers: all prepped and the first batch into the tank. I decided to keep the amps exactly the same as the that used for the pedal cages. I do not know how to work out the surface area of these complex shapes so I am going by a rule of thumb. The first pair of caliper parts went very smoothly, the voltage was extremely consistent throughout at 14.2 volts. Less than with the cages at the same amps. Does this mean that the power needed to maintain 1.17 amps is less for the brake calipers? Presumably so. Is this because they have a smaller surface area or the material is different: I do not have the foggiest.
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The parts fizzed nicely form the start and continued to do so throughout. Everything look good. Time up and into the dye and then fixed. They looked great! Blimely this is easy!! The other pair of caliper parts were next, exactly the same procedure, everything the same. Ummm, not the same fizz and not the same voltage draw. But everything was the same?? I carried on with the experiment, finished in the tank, put in the dye and had a look. Rubbish. Despite everything apparently the same these came out hardly black at all. Deep breath and start again. I stripped them and scrubbed them in the caustic soda, scrubbed them in the nitric acid and, with the finish looking consisitent, popped them in the anodising tank. I decided to up the amps from 1.17 to 1.25 amps as it is really the only varible I knowingly control (given I am a complete muppet at this). This was inspired, the voltage draw, a little more than the first batch, was conistent throughout and a really good stream of super fine bubbles was observed from the calipers parts. Time up, into dye, have a look, Hell Yeah, and then fix the dye. Voila! a set of MX900 calipers in black fit for any Laserlite!
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I have infilled the MX logo with acrylic paint, the most slap dash part of the job lacking a steady hand but meh the job is done. All I need to do now it refit the quick release by forming the new rivet, scared about this but we will succeed.
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