Small Scale Aluminium Anodising in the Home Workshop

[Music] you hello first off let me just say this isn't meant to be any kind of anodizing how-to it's more of a what did I'm not any kind of expert I've only done maybe a dozen small parts over three years or so while I was getting the stuff together to have another go I thought I'd share my experience from a UK perspective that's a lot of what's out there is by us authors this is the piece I'm gonna wanna dice it's gonna be part of a puller that I'm working on I'm not sure what great the aluminum is and it remains to be seen how well it will work the first thing to say is that unlike painting or other coatings anodizing won't hide anything if you parts not perfect but you're happy with it carry on but remember the way it looks now is the way to look in the end I'm aiming for a satin brushed look for this part here I'm using 400 grit wet and dry with a bit of wd-40 to bring all the surfaces to a similar-looking finish I'll put the part to one side for now and wash my hands and your left the gloves out for something before I do anything with any chemicals here's a disclaimer sodium hydroxide and sulfuric acid can both be very dangerous you need a tidy space to work gloves eye protection and old clothes trust me on the old clothes the acids cost me two pairs of jeans so far when making all the solutions always add the chemical to the water not the other way around there's various confusing rhymes out there that are supposed to help you remember this but this is how I see it chemicals are dangerous Omri sharks are dangerous think of the chemicals as hungry sharks a drop of water into a tank of concentrated chemicals is like a drop of blood into a tank of concentrated sharks they're gonna go berserk possibly covering you in a shower of boiling sharks on the other hand if you drop one shark into a tank of blood you're probably going to be okay I'm using deionized water for this film I've used reverse osmosis water and that work fine I've not tried distilled some people writing soft tap waters good enough I usually use an etch bath made with 2% sodium hydroxide this is fairly easy to get hold of and can usually be found in the cleaning aisle of the supermarket the upside is the parts are made really clean which is crucial the downside is any highly polished finishes tend to be made a bit dull deletions are by weight not volume and my storage bottles hold two and a half liters for water two and a half liters weighs two and a half kilograms two and a half kilos is 2500 grams and two percent of 2500 grams is 50 grams the 50 grams of my final weight accounted for I'll need two thousand four hundred and fifty grams of water from this point on it's gloves and glasses all the way I start by weighing out the water [Applause] then I weigh out the caustic soda remember the reaction is exothermic always add the chemical a little at a time to the water if the bottle starts to feel warm leave it for a few minutes to cool before adding some more chemical next comes the anodizing solution itself the first time I had to go anodizing I tried sodium bisulfate on the grounds that it's meant to be safer and easier to obtain there's a link in the text to a site where they've had good results with this but I couldn't get it to work bear in mind though I had no previous experience to back me up and I used the cheapest sodium bisulfate I could find which could have been icing sugar for all I know most American instructions begin with go to your local auto parts store and get a quarter battery acid you'll struggle with that in the UK battery light to light is available but it's not common you certainly won't get it in Halfords anyhow by chance I came across a type of drain cleaner there's 91% sulfuric acid in a local DIY place it was just on the shelf not even behind the counter no ID required I was a bit surprised given you can't even buy pointy things in the UK until you're 18 as before I'm mixing by weight not volume I want to end up with a total of 2,500 grams of solution 15% of that leads to the acid which is 2,500 times 0.15 which is 375 grams now my drain cleaner is only 91 percent acid so I'll need a bit more than 375 grams in fact it'll be 412 grams I've already got four hundred and twelve grams towards my 2500 grams of finished solution so I only 2,500 - 412 equals 208 8 grams of distilled water first away the distilled water then a way out the acid it looks like I need to restock as I'm just shy on the 412 grams are calculated but a slightly weaker mix shouldn't have too much effect to start with my waters at room temperature at about 18 degrees C remember add the acid to the water and add a bit at a time keeping around the temperature here I've added about a third of the acid and GABA 10 degree rise how did the rest of the acid gradually over the next quarter of an hour or so keeping an eye on the temperature I was mainly trying to avoid the bottle going soft with the heat and collapsing under its own weight interestingly it goes from purple to yellow one is diluted and it goes clear the first time is used for anodizing of every faith in the bottles I use and I've never had one link but just in case I keep the mixed solutions inside extra tubs when they're not being used and I store them on the bottom shelf seems like this way he will cause least mess if one were to let go the last solution to make hope is the dye there's plenty of options for dye lots of people like RIT liquid fabric dyes but I can't get those locally and online the close to the cost at metal dye so I haven't tried them this type of dial on is what all my local shop stock I've tried a couple of colors with zero success there's a lot of stuff in the pouch certainly more than just a few grams of die it's probably great for fur breaker but it's rubbish for metal I've also tried some old fashioned dial on cold water dyed that are picked up to car boot sale evany black emerald green and tangerine orange all worked to a greater or lesser degree this is a piece of scrap dyed with the black this is the orange which has worn off quite a bit and this is the green which didn't work too well because the panel wasn't cleaned properly I found the cold water dyes don't like being stored for months on end over time little bits form in the solution which spoils a result a coffee filter will clean out but it's a messy business and I wouldn't recommend it if you've time to experiment that replace his reporting success with fountain pen ink inkjet printer ink and various other things this will be my first time using proper anodizing dye the instructions say one gram to liter should give good results my diet or whole 750 mils so I need 3/4 of a gram of dye which is just a pinch so that's all the solutions ready to go the next thing is the power supply small parts like mine don't need anything very powerful and this one will give 5 amps of 24 volts for my first attempt I used it as is but after doing some research I found out that a constant current supply gives the best results so I built this add-on unit it's just a bangle switching regulator module put in a box it means I can set the target current and leave it to look after itself instead of having to manually fiddle with it right the way through the final bit of homemade equipment is this magnetic stirrer it's just a little motor an ebay speed control module and a nylon disc with two magnets glued into it these are called fleas are and come from China for not much money I admit this is a bit overkill but it does help to stop bubbles sticking to the surfaces and make the cathodes from thick aluminium foil cut from these party platter plate things they asked for a few girls but are basically disposable LEDs supposed to be a good choice for cathodes but it's surprisingly hard to get hold off I use two or more large cathodes depending on the shape of the part to try with in reason to make all the paths between the electrodes similar my reasoning goes like this if I used a single post type cathode the nearest end to the part would initially see all the current and as the oxide layer was built up an area further up the part might offer the lowest impedance and see some action but it's anybody's guess if the opposite end were anodized at all in order to set the power supply I need to know the surface area of the part I'll just treat it as a rectangular bar and ignore the holes that gives me two surfaces of 11.4 by not 0.9 two surfaces of 11.4 by two point two and two surfaces of 0.9 by 2.2 all told that 74.6 for square centimeters this value is plugged into a seven twenty rule calculator entering the numbers I get a hundred and twenty minutes per mil of thickness for a current of point four eight amps I usually leave the ampere for setting at a default value of six the electrical connection to the part is made with soft uncoated aluminium crushed wire where possible I make two or more connections the reason being as the anodizing progresses the insulating oxide coating will build up all over the part if contact is broken their chances of reconnecting to the exact spot are zero the chances of getting a good contact elsewhere could be difficult if a decent layer of oxides already built up I fold a big end enough to jam it into a suitable hole the connection needs to be good mechanically as well as electrically to minimize the chances of the part falling off and having to fish around in the bottom of the acid tank to get it back the next bit is really important the part must be spotless any greasy fingerprints will be visible on the finished item I start by cleaning thoroughly with brake cleaner until no visible dirt comes off the part I tend to reuse gloves until they fall apart but for this bit I use a clean pair that won't have any oil on them the part and the aluminium connecting wire are given a final clean with M ek and then the wire is fitted firmly into the part with a hanging loop of one end you the first chemical bath is the sodium hydroxide etch it gets about 20 seconds or so in here and then rinse in clean water here power supply short-circuited and the maximum current is set to that calculated by the 720 rule the to cathode plates are connected together and then to the power supply negative once the tankers we with the 15% sulfuric acid solution the part is hung inside on a wooden stick something like equidistant between the cathodes the circuit is completed back to the power supply after a few seconds you can see thousands of tiny bubbles forming in the tank each bubble creates a minut splash of acid when they reach the surface and burst I'd strongly recommend likely covering the tank with the tissue or everything in the vicinity will start corroding and that's it for two hours just come back and check nothing's gone wrong every so often when the time's up the power is removed and the part is thoroughly rinsed in water next comes the dyeing this is optional the part can just be life self color if you just want to make it a bit more corrosion or scratch resistant just add you take the part in the dye until it reaches the color that you want this is my first go with real metal dye and I have to admit it's miles better than anything else I've used the color is deeper and is fully absorbed other dyes I've tried look okay until the rinsed when a lot of the intensity just washes off the final stage is to seal the part I'm simmering it in boiling water for about 40 minutes once cooled of the connecting wire can be removed and the jobs finished this is one of my better attempts though it's still not perfect I've got a bit of a tied mark on one side I'm not sure what caused this perhaps drying the part between baths would help to finish up here's the part fitted in the puller that I was making and that's it thanks for watching [Music]

Channel: The Recreational Machinist

Views: 1,121,187

Rating: 4.9119048 out of 5

Keywords: low current density, metal dying, anodising, anodizing, anodise, anodize, anodising aluminium, anodizing aluminum, anodising at home, home anodising, how to, DIY, in the shed, in the garage, sulphuric acid, battery acid, homemade, custom, shopbuilt, in the shop, machinist, machining, home machine shop, lye, caustic soda, sodium hydroxide, battery charger, anode, cathode, etch

Id: L2RKze7baJw

Length: 15min 10sec (910 seconds)

Published: Wed Sep 19 2018