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 

[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

[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.

[griff]

Speak to Steve Animal about re-riveting calipers, he's done a bunch of 'em

[Chris123]

Use titanium wire for connecting parts, it doesn't erode, doesn't need stripping after every use and makes a far better connection.

A much better way of doing it to to use constant voltage rather than constant current, you don't need to **** about working out surface area then. Although you would likely need a better setup with a pump to circulate the electrolyte.

What ratio of acid are you using and what temperature is the electrolyte at?

[Avro]

Moving house today so my anodising should recommence soon.
Thank you for the input Chris. I read up quite extensively before beginning these experiments and found a concensus that constant amps was the best way? Using constant volts would be easier, and require a more simple set up, but would it be any better? As I have said I am finding my way as best I can and very happy to make mistakes and look stupid!

The electrolyte is at around 20 degrees C. I bought a fishtank heater, thinking I would need one, but this has not been required yet. A fishtank pump was also on my list to buy but I don't think I need it, at least not for my little tank. When I set up the bigger tank then I think I may get a pump. I Suspect that larger parts my harbour more bubbles so agitation will be required, it certainly will do no harm.

I am using 20% acid solution.

[Avro]

*waves* Right, back in the game.
A few well earned days off work and back into the lab, or as it is now called 'The Man Cave'.
I had planned to ease myself back into the anodising with small parts again. I picked up a Hatta MX100 head set, for my Laserlite, off the Museum recently which was raw with the remnants of gold anodising visible. My plan was to anodise the cups and top nut black. However this will not be possible as the cups have steel inserts to form the bearing surfaces. I will have to paint the headset, never mind.

So, I had to tackle one of the larger items on the list and set up a bigger tank. This is a journey into the unknown as I do not know what difference the larger tank volume and distance between cathodes will make. Anyway, only one way to find out. One fun thing was making the acid solution. Into a 10 litre bucket I put around 7.2 litres of de-ionised water and then, very carefully, added 1.8 litres of 96% sulphuric acid. When you do this you get a scarey roar when the acid hits the water, quite alarming really! My set up is just as before, no changes there.

The first victim was a raw Sugino chainwheel for my Laserlite. As the Laserlite should have a black finished chainwheel with machined finished teeth I had a go at masking. This is done with polyester sticky tape. Here is said chainwheel, sanded, polished and masked, ready to be cleaned and etched.
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In it went into the caustic soda solution for around 5 minutes. If fizzed immediately and very aggressively, I think I have made a stronger solution than before. All was well and the wheel took on a grey-gun metal finish. I forgot to get the nitric acid solution (it can be tricky as nitric acid is for restricted use only) so I had to desmut as best I could by hand in de-ionised water. This is fine but dipping in nitric acid is far, far better, that much I have now learned. Here is the wheel just out of caustic soda solution. The colour change is the imputities sitting on the surface.
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Then into the anodising tank. This is where things were very different from my previous attempts. My acid solution is 3-4% stronger than before and the part started to fizz instantly. I had not observed that before. Also, when the power was turned on, the voltage did not ramp up in the same way at all. I had very accurately worked out the surface area, quite easy this time given the shapes, so set the amps accordingly. The voltage slowly ramped up to 5.3v and stayed there. Before I was seeing voltages typically between 12 and 15v. I do not know why such a low voltage. Something to do with volume of acid or distances between the part and the cathodes I guess. Anyway I let the experiment run for the allotted time. Then into the dye. Then to fix or seal the anodised layer. Before I was using the temperature method where you hold the part in water at around 90 degrees C for 20 minutes or so. This obviously impacted on my electricity bill and is terribly inefficient. So, I tried a chemical that allows fixing at room temperature and it worked fine. It adds a complication as it is partially consumed each time it is used. This alters the ph of the solution and the efficacy of the process. You have to add more chemical to maintain the correct ph, I think this in turn keeps the concentration within parameters but I am no scientist!

Here is the chainwheel out of the dye.
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As you can see the masking failed. Next time I will spend much more time on this element. Not to worry as removed the anodising on the teeth using a fine paint brush and caustic soda solution and, voila, a black Sugino chainwheel with machined teeth detail. I am pleased with it and the job is done.
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[In2bmx]

Nice work 

[MartyC]

That's a pretty good job, might try that trick on a chain ring I have 

[Avro]

I have done a bit more today, parts for my 'Racergoose' aka Bobby Encinas bike.
The Sugino cranks started out as silver anodised, the SR chainwheel was raw. I did not put a lot effort in preparing these, the chainwheel none at all. I am prioritising a couple of other builds and my time is limited. The lack of prep. work does show, also my 10 litre tank was not really big enough to suspend the cranks and you can see where one has been touching the bottom. On the chain wheel you can see a finger print Grrrrr.

Cranks coming out of the caustic soda solution and still smoking:
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...ready for the anodising tank.
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Cranks being cooked:
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Blue cranks:
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Blue chainwheel:
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[Avro]

...oh, and blue fingers
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[SH101]

Nice 
Would you do any anodising for anyone else ?

[Avro]

Within reason! Small parts like those shown, I hope to do rims and handlebars but need to research a whole lot more and get more experience. After all it gets a little dull redoing the same piece to get experience
If it helps someone with a build, then sure but remember I am working in a mancave in my spare room, I have a job and committments; I am not a professional anodiser!

[dancetothedrummersbeat]

Excellent work 
I absolutely love these threads! This is where the forum based sites are so much better than facebook. Great 'how to' guides and threads that people can refer back to. Keep it real, keep it  and long may it continue 

[MartyC]

Amen ^^^^^

[monkian]

Awesome work Peter. Great thread

[Jmc Jason]

What an awesome thread. I have always thought wouldnt it be great to have a go but time patience cost.  Put it in the to hard basket
well done for having a go and great results, 

[Swivel]

Awesome thread, needs to be a sticky!

Great work mate 

[CustardLips]

Awesome thread, needs to be a sticky!

I agree... them XCll's look awesome Peter. 

[insectbones]

Awesome thread, needs to be a sticky!

I agree... them XCll's look awesome Peter. 

I'll third that, great thread this 

[Avro]

*cheers* and thanks for that. The spare room, sorry Lab, sorry Man Cave, has run out of work on the anodising front. However, I am trying to source dated Tech 3 levers for my Laserlite which may need re-anodising. I have the parts and tools to rebuild the levers, so I should be able to start up soon. Rebuilding the levers presents a new challenge, the rivets are not shouldered, but I am determined.

I know many take a dim few of the restoration of period parts, and I was about to take them on, but nah, all is good. Thanks again, any input is much appreciated.

[In2bmx]

Great work ..

Thread set as Sticky 

[Avro]

Blimey, a stickie! I am honoured, and not a little pleased.
More to come I am sure, most importantly a pair of Tech 3 levers for my Laserlite which I will record, warts and all, as they progress.
Thank you agian for the continued interest and encouragement.