That's really interesting Flex, thank you for having a crack at it and showing us the results. I have been very keen to see this done and also to analyse how it holds up against the weed at Lilacs (and at my patch if it ever regrows). If you have stuffed the fin, just drop me a line and I will swap it for a new one for free. I can always use failed experiments for more experiments on foil shape and cutdowns etc.
Way back when, I approached a commercial operation to anodise the fins they told me that because it was cast aluminium it would contaminate the tank and therefore would be very expensive to do - I don't know enough about the metallurgy of cast aluminium to know why this is the case.
Just a couple of points to add - there is a bit of research out there on the effect of surface porosity on attached flow. It seems to make bugger all difference, whereas protuberances have the opposite effect. I used to use a bit of spray putty to fill them - now I don't bother.
If you whack your fin in the dishwasher, the hot water and cleaning tablet is alkaline enough to give the same effect as a low-level caustic bath. Like the food dye, the rinse aid leaves you with some interesting patterns through the aluminium.(I did think initially the stainless steel cutlery might be the problem, but if there was no physical contact it was hard to see a stable enough galvanic pathway.) Once again, I need to revisit my material science to understand that properly.
And finally, as a COVID lockdown nerdy bonus on the side - If I understand the physics of fluids and foils well enough, all foils that attempt to hold laminar flow for as long as possible are affected by surface smoothness. (Eg NACA 64 series and similar Eppler designs) Foils that simply aim to keep the flow attached by avoiding low-pressure peaks, with relatively low lift compared to the aforementioned 64 series, are not as sensitive to the surface finish. (Eg NACA 16 series-> propellers.) However, leading edges are a different kettle of fish!
Interesting. I did sand and polish my fin to 2000 and give it a polish with turtle wax. Only cos it looked sooo good being nice and shiny. Now I've never had an issue with spin outs and it's handling the chop really well. Still off the water atm but looking forward to further experiments 
Hey Fangman, I did PM you prior to posting via that oldskool way. I certainly am no expert but your fin really did feel more solid with a crap surface finish. Leaves some question on where the line between crap and polished and which bits to finish at what git are. I spent the last day and a bit setting up my cheap chinese CNC mill (which I bought to cut wood) to cut the powerbox profile better as I know I need (want) another Fangy fin. Trial and error sanding is not the way forward here. The Powerbox fit was the hardest part to get right with your fin (for me) and it seems to my surprise that I can mill Al and Steel no prob with this CNC. One can of worms opened.
Anodising is cheap as...battery acid is extremely cheap if you buy in bulk so the main cost is labour after the initial setup. I can't remember much chemistry but I would think any impurities in the cast should either, A) do nothing, B) vaporise or C) react and sink to the bottom. I can't see how they will hang around and contaminate the solution.
The main purpose for this fin is Lilacs end of year mission as last year I learnt the hard way with a bad fin. The anodising was a way maybe to extend life and add bling. I don't expect a free fin but if you have reject cast material to experiment with to get the speeds and feeds right on the CNC it would be good to try before trying on the real thing. Whilst you lost me on the nerdy NACA stuff a bit I've been going down the rabbit hole on this stuff and brain hurting...opened even bigger can of worms in the process...Have you come across this guy...Fagg as opposed to Fang for his doctorate in Philosophy back in '99..I thought Philosophy was about meaning of life and stuff but seems it is applicable to windsurf fins too:- eprints.bournemouth.ac.uk/12235/1/Simon_Fagg.pdf (beware, its long and maybe well out of date)
In the process of reading this I came across another living legend in Mandurah who may have stumbled across and built..over 30 years ago mind you, the key to next level speed...and then forgot about it. Nothing to do with fins at all. I've sent him an email this morning..hopefully he will reply before I start butchering my gear. End result of the last few days experiments, surface finish questions and reading is I think I need a flow tank to experiment some ideas on as well as play around with all this stuff. I'm thinking the pool pump and some off cuts of poly carb....Should keep me busy.
Select to expand quotekato said..
Interesting. I did sand and polish my fin to 2000 and give it a polish with turtle wax. Only cos it looked sooo good being nice and shiny. Now I've never had an issue with spin outs and it's handling the chop really well. Still off the water atm but looking forward to further experiments
Kato, I'm pretty sure the detrimental effects come more from me changing the profile due to enthusiastically chasing some pitting out rather than the surface finish. Those flapper disks sure chew material quickly... You can clearly see the depression on the first polish photo. No one has reported degraded performance with finer finish so suspect it has something to do with what Decrepit said that an imperfect fin can get flow detachment with a polish finish. That said, I still got 4 PB's with this fin on its second run so it can't have been all bad. However, I was really struggling with the gybes on this day when usually flat water gybes are easy. I seemed to be crashing in many of the left hand turns and that depression was on the left side of fin...not sure I can explain why though...
Sorry Flex, I think the pm has got lost in the ether somewhere. 
Quick points: The paper by Fagg looks like a good find though. I will defo have to plough through that this evening and see what I can learn.
Failed experiment fins eventually go back to the foundry to be recycled, but I will check the returns 'bin' to see what's in there that might be suitable.
You may have already found Pepe47 in Mandurah, he has lots of experience with design and CNC fin manufacturing to the highest level - they are beautiful!
Anodising - the commercial guys said the tank would need cleaning after each batch. I guess the crap falling to the bottom of the tank is issue...(?)
I am very interested to see the outcomes on any experiments esp. the 'flow tank' - there is so much stuff that I don't know and just taking educated guesses at. Keep at it Flex!!
I am on the final stages of getting some V4's ready for action. In the process I have found some laws of the universe cannot be thwarted. For instance, the Law of Certain Fail. Exhibit A. The FF18 V4's left the foundry, which is about 70 kms away from me, in late August. Australia Post, in their wisdom, decided to put them on a truck to Sydney. Once there, they sat untouched for two weeks (due to the congestion with lockdown) before they were put on a truck back to WA, and finally delivered just shy of one month after being posted.
Being keen as a bean, I immediately set to work and I was in the final stages of finishing when, of course, I dropped the fin while buffing. Toast falls butter side down, and fins always fall on a pointy bit. To uphold this indisputable truth, the fin fell toward the concrete trailing edge first. Just as I started to curse the imminent munting of trailing edge versus concrete, the Gods of Luck intervene by placing my power cord in the exact position to intercept the trailing edge before its crunched on the concrete. For a split second the fin is saved. Then the Gods of Sh!tf@ckery laugh and the trailing edge slices through the power cord and contacts the 240 volts of mischief within and just bursting to get out. Flash and bang! A lively short circuit across the fin for a microsecond before the RCD kicks in. Surely the odds of one neatly cleaved power cord and a fin saved from the concrete, but now with a neat chunk blown out of the trailing edge by the electric current, are too high to be just down to chance?
Select to expand quotefangman said..
I am on the final stages of getting some V4's ready for action. In the process I have found some laws of the universe cannot be thwarted. For instance, the Law of Certain Fail. Exhibit A. The FF18 V4's left the foundry, which is about 70 kms away from me, in late August. Australia Post, in their wisdom, decided to put them on a truck to Sydney. Once there, they sat untouched for two weeks (due to the congestion with lockdown) before they were put on a truck back to WA, and finally delivered just shy of one month after being posted.
Being keen as a bean, I immediately set to work and I was in the final stages of finishing when, of course, I dropped the fin while buffing. Toast falls butter side down, and fins always fall on a pointy bit. To uphold this indisputable truth, the fin fell toward the concrete trailing edge first. Just as I started to curse the imminent munting of trailing edge versus concrete, the Gods of Luck intervene by placing my power cord in the exact position to intercept the trailing edge before its crunched on the concrete. For a split second the fin is saved. Then the Gods of Sh!tf@ckery laugh and the trailing edge slices through the power cord and contacts the 240 volts of mischief within and just bursting to get out. Flash and bang! A lively short circuit across the fin for a microsecond before the RCD kicks in. Surely the odds of one neatly cleaved power cord and a fin saved from the concrete, but now with a neat chunk blown out of the trailing edge by the electric current, are too high to be just down to chance?
nice fangy
love your work.
Select to expand quotefangman said..
I am on the final stages of getting some V4's ready for action. In the process I have found some laws of the universe cannot be thwarted. For instance, the Law of Certain Fail. Exhibit A. The FF18 V4's left the foundry, which is about 70 kms away from me, in late August. Australia Post, in their wisdom, decided to put them on a truck to Sydney. Once there, they sat untouched for two weeks (due to the congestion with lockdown) before they were put on a truck back to WA, and finally delivered just shy of one month after being posted.
Being keen as a bean, I immediately set to work and I was in the final stages of finishing when, of course, I dropped the fin while buffing. Toast falls butter side down, and fins always fall on a pointy bit. To uphold this indisputable truth, the fin fell toward the concrete trailing edge first. Just as I started to curse the imminent munting of trailing edge versus concrete, the Gods of Luck intervene by placing my power cord in the exact position to intercept the trailing edge before its crunched on the concrete. For a split second the fin is saved. Then the Gods of Sh!tf@ckery laugh and the trailing edge slices through the power cord and contacts the 240 volts of mischief within and just bursting to get out. Flash and bang! A lively short circuit across the fin for a microsecond before the RCD kicks in. Surely the odds of one neatly cleaved power cord and a fin saved from the concrete, but now with a neat chunk blown out of the trailing edge by the electric current, are too high to be just down to chance?
RCD ???
Select to expand quotekato said..
RCD ???
Sorry my bad Kato: RCD: residual current device. An Important bit of kit to stop clowns like me electrocuting themselves.
en.wikipedia.org/wiki/Residual-current_device
used to be known as ELCB, Earth leakage circuit breaker. So basically it's looking for an imbalance between active and neutral. the difference is what's going to earth somewhere. So in Fangy's fin, situation, it's shorting active to earth.
Waisted or Wasted?
I somehow ended up reading up on the theoretically low drag Sears-Haack body. ( I have pasted in some links to the wikipedia entries for a summary of each item of interest for further backgrounding if you are really desperate to get to sleep)
en.wikipedia.org/wiki/Sears-Haack_body
This turned into reading some research on avoiding wave drag. This occurs primarily in the region of shock waves but exists in some form wherever there is a localised increase in pressure. Long story short, a bloke named Whitcomb came up with the a rule that dictated that an aerodynamic shape should change in cross sectional area as as smoothly as possible from front to rear in order to minimise wave drag.
en.wikipedia.org/wiki/Area_rule
Early supersonic aircraft had wasp-waist fuselage designs in order to accomodate the increased cross sectional area caused by the wings and tail.
All of this assumes that the plane has no yaw, which is not the situation on a fin, but I couldn't quite resist the temptation to do the experiment regardless. I realise given that the shock wave effects are due to a compressible fluid, which obviously water isn't, the theory doesn't extrapolate to hrdrodynamics directly. Quite possibly this might be yet another situation where I have applied the incorrect theory to situation and still get a result. Regardless, I have trimmed the fillet to create more area to diffuse and reduce the pressure peak in the area from the foil max thickness.
Exhibit A: Exaggerated Wasp Waisted FF (prototype 16 series foil shape)
I don't know how much reduction is required, so I have re-shaped the fillet to what I think is an exaggerated waist in the hope I will be able to pick some change, for better or worse, in the fin performance.
I think I can visualise what happens on the high pressure side, but the low pressure side is not so clear to me. What happens to the pre existing vortex flow that that was created by the fillet, does it get get disrupted or intensified or what?
If I feel there is something to be gained I will sit down with the CAD files and try and work out the amount of fillet reduction required in order to maintain the same cross sectional area.
So the next job is to try it out and see what happens.
Not wasted
First run yesterday. I can say with a good degree of certainty that the fin is no worse. It did not misbehave in any water conditions. It may just be confirmation bias, but the fin actually felt less draggy and consequently faster. Given this is almost the worst possible scientific method, there is lot more testing to come. On the plus side, because I have posted this on the interwebby thing, I am pretty sure some sort of magic happens whereby the sciencey stuff becomes automatically 100% factual and correct. In any case, the initial indications are that wasp waist FF might be on the cards as a recommended hack. More to come when I have trashed another few fin fillets ...
^ So the Waisted fillet is further research of Katos reduced fillet positive results?
Keenly following your findings.
Fangy, do you ever sleep???
Select to expand quoteolskool said..
^ So the Waisted fillet is further research of Katos reduced fillet positive results?
Keenly following your findings.
Fangy, do you ever sleep???
I have it on good authority that Kato will soon be called to front ICAC to give evidence on the Corruption of Fillets, Fins and Physics 101, so I can't say anything more until this matter is heard. 
As for sleep - yes defo. It's one of my strengths and possibly when I do my best work.
Select to expand quotefangman said..olskool said..
^ So the Waisted fillet is further research of Katos reduced fillet positive results?
Keenly following your findings.
Fangy, do you ever sleep???
I have it on good authority that Kato will soon be called to front ICAC to give evidence on the Corruption of Fillets, Fins and Physics 101, so I can't say anything more until this matter is heard.
As for sleep - yes defo. It's one of my strengths and possibly when I do my best work.
What did I do wrong??. I just drive the thing your honour
Somewhere back there.... Decrepit said something about polished fins and laminar detachment.... 
In that Fantasia period of my windsurfing speedsailing, distant history, when Mal Wright was designing and CNC cutting new assy speed fin prototypes every other week, (on this home made CNC machine!!! 
) and Sandy Point was Duneless, crescent curved, sexy speed sailing heaven, Mal would come down on every good forecast with his new creations.
We had a cathartic relaxation routine every night before the big wind day, (quite a regular occurrence in that past era - the big winds I mean) sitting on the verandah, spray putty painting and wet and dry sanding fins to within an inch of their life - or is that a Micron? Of course, our conversation themes tended to focus around physics and mathematical stuff that Mal was fluent in, and I understood nothing of. But I kept asking dumb questions anyhow.
Somewhere in there I mused about the effects of polishing v's 800 grit matt finish and Mal decided we should experiment. It turns out that that soft 3D spray paint/putty stuff in a can polishes up really, really well with some very fine cutting compound paste and a soft cloth. We soon had some fins staring back at us with distorted versions of our own likeness! Slightly disturbing now I think about it, but we were on a mission and that part didn't register at the time. 
i can definitively report that we noticed,................. absolutely no increase in speed, that could not be accounted for in about ten thousand other ways. Blind controls we didn't have. 
BUT! One thing I did notice was that on almost every first run with the mirror finish fins, I felt.... a kind of intermittent incipient spin out. I called it squirrilly in the complete absence of any kowlegable, technical expertise to describe the phenomenon. It's not something you would call a positive outcome for your confidence.
The strange thing was that subsequent runs (yes, amazingly I persevered in putting my body on the line for the sake of science), that effect seemed to quickly disappear on second or third runs, and the fins behaved in a much more familiar way. That is to say, rock solid and FAST!
We never did formulate a good hypothesis to explain this observation, but maybe it was related to the very thing that was mentioned above somewhere by the great, wise, 'Decrepit' elder of windsurfing about detachment of laminar flow, and perhaps proposed what we didn't want to believe: That all our meticulous sanding, didn't work like we thought it should 
.
Shrug?!
Those good old days of Sandy Pt. in it's prime, sure were fun though.
Just a few of the early TM asymmetrical prototypes Mal Cut: left to right (roughly) V1, V2, V3, V4n, V4r, and god knows what the two on the right are, but they were all Srarboard tack assys.
Select to expand quotesailquik said..
>>>>maybe it was related to the very thing that was mentioned above somewhere by the great, wise, 'Decrepit' elder of windsurfing about detachment of laminar flow, and perhaps proposed what we didn't want to believe: That all our meticulous sanding, didn't work like we thought it should .
Shrug?!
Those good old days of Sandy Pt. in it's prime, sure were fun though.
Thanks Daffy, but I was only repeating what Mal had said somewhere. Something along the lines of, high polish only works on perfect/near perfect foils, otherwise you'll probably get detachment, the creation of a small boundary layer helps the flow to follow the foil's curve.
I'm not surprised Mal tried a high polish, as I'm sure his foils would have been very good.
Select to expand quotedecrepit said..sailquik said..
>>>>maybe it was related to the very thing that was mentioned above somewhere by the great, wise, 'Decrepit' elder of windsurfing about detachment of laminar flow, and perhaps proposed what we didn't want to believe: That all our meticulous sanding, didn't work like we thought it should .
Shrug?!
Those good old days of Sandy Pt. in it's prime, sure were fun though.
Thanks Daffy, but I was only repeating what Mal had said somewhere. Something along the lines of, high polish only works on perfect/near perfect foils, otherwise you'll probably get detachment, the creation of a small boundary layer helps the flow to follow the foil's curve.
I'm not surprised Mal tried a high polish, as I'm sure his foils would have been very good.
Yes, but you remembered it! I am sure I have heard such gems many times and they have completely escaped me now.
Oh yes, the fins were cut to amazing tolerances, and became 'micron' accurate when he went to professionally CNC machined moulds for the V7 and V8 Carbon moulded models.
I wondered if the polished effect/shine or something Hyrophobic in the paint, polish or cutting compound wore off after a couple of runs.
Maybe it supports my now lazy notion that lots of fine filling and sanding does not improve a foil that is very good to start with?
Just to confuse things even more on the unpredictable squirrely handling conundrum: The 'No-Slip condition' dictates there will always be a layer of water molecules on the surface of the fin, moving relatively slowly compared to the free flow, until such time as some force convinces them to give up their mutual attraction and be somewhere else. These Viscosity effects decrease with an increasing Re number, but the Inertia effects increase. Some clever fella that I can't remember, said that at such high Re numbers ( anything over 10^5) the inertia effects are so dominant the flow show be considered to be in pipes, and so rather than stream/flow lines, instead they are "pipelines" of mass and more allergic to going around corners more than any US muscle car ever was.
I thought that I would do an update as I've been playing with the FF28 for a bit now.
I've now tried polish v unpolished and although there wasn't much speed difference the polished felt slipperier and I would probably continue with the shine.
This fin was designed to get me to 30kts in 8/10 kts which it does but I'm finding the I'm using it more and more in stronger winds. (20Kts with a 7.7) Its opened up some areas that we don't sail cos its just too shallow. Yesterday was a perfect example as I could explore the shallow areas as the rest were still playing on the edge in the chop.
The rake also means that when you hit something its not so brutal. I unfortunately hit a large stingray at 25kts, not so good for the ray but I didn't crash. Hopefully it survived.
No issue with chop either which was a surprise, It reconnects really when bouncing out of the waves, yes I took it for a play into the surf. Small waves.
Look forwards to returning to Lake George and chasing some higher numbers with this fin now that I had some solid sessions with it.
Sounds like you can throw all your other fins away Kato ..it's turning out to be a allrounder
looks like I'm about to sand my fillet 
Select to expand quoteTardy said..
Sounds like you can throw all your other fins away Kato ..it's turning out to be a allrounder
looks like I'm about to sand my fillet
Not yet, but it is pretty great for light wind and weed.
I do want to confuse Ross and get it to 40kts too
Select to expand quotekato said..Tardy said..
Sounds like you can throw all your other fins away Kato ..it's turning out to be a allrounder
looks like I'm about to sand my fillet
Not yet, but it is pretty great for light wind and weed.
I do want to confuse Ross and get it to 40kts too
You are not setting a high bar there Kato...these days I am confused by half the threads on SB and even struggle with the opening instructions on my Weet Bix packet, let alone when you do freakish speeds on the recycled tail fin off an A380.
Had the pleasure of sailing with the Fangman a few weeks ago on his home turf. As nearly always, was sailing with my first Fangy fin22. The one I butchered anodising 11 months ago. First time though the master Fangy checking it out. Despite a lot of distance he reckoned it was holding out very well. ( I haven't calculated exact distance logged on this fin but it must be in the order of 4000km. Mostly in weedy abrasive conditions and lots of dredging. All posts logged but can't find a way to easily determine actual distance but some out there might be able to.)
With the complete absence of any wind I was motivated to have another crack at anodising my other 3 Fangy fins (and hopefully soon one from the Fangy fin skunk works). I have my favourite light wind 24, my ultra light wind 28 and my high wind 20 (cut to 18). All fins except the 18 have had lots of use where as the 18 has had one run in marginal conditions and I could not get upwind at all (finish was 40 grit pass of 20 seconds)
From the first attempt and reading more, the surface finish is key to getting a nice anodising coating. It was/is pretty clear that my first attempt (look further back in this thread for photos) was surface finish was lousy. I blame polishing as you can polish over a surface and it looks great but the underlying surface is pretty dodgy.
So this time around I spent a lot longer with the 1200 grit paper and whilst tedious it really started to show the underlying grain structure. Polishing at any time and it looked a million dollars but hitting it with the 1200 again you could see the effects highlighted with the dye in my first attempt.
It was a law of diminishing returns so after way too long with the 1200 grit I called it and brought out the polish. There was still porosity but I have a feeling there is no way to completely eliminate the porosity. (I have 1500 and 2000 grit paper but thought I would try this finish as a starter)
Effort to this point = 4hrs
This time round I thought I would skip the desmut process. The thinking being the Fangy fins have lots of porosity and the etching just enlarges that porosity. To compensate I pressure washed the fin, hit it with methylated spirts, pressure washed, acetone then pressure washed, then hot soapy water/scrub/rinse/do it again.
Chucked it in the anodising esky and this time did 90 minutes at maximum current I could achieve from my 12V camp battery which was average about 15amps. The acid looked black this time. Skipping desmut starting to look like a bad idea.
Brought it out and fin looked a lot darker and there was what seemed like a speck of grass on the fin, could not blow it off so tried my finger...damm, huge finger print. ****, what to do...decided to cook it off and see the result so steamed the fin for a good hour++ (probably 2 hrs)
Brought it out and was surprised that the surface was finger paint. This black stuff washed off easily but just kept coming...at least the finger print also washed off. Truly unbelievable amount of impurities...First 2 attempts I did desmut with Castic soda and the acid is crystal clear. Note, I washed 4 times and each time the black **** kept coming out so pretty sure the back bits you can see in photo will disappear once on water.
Not sure if the anodising is fine and all the impurities came to the surface. (oddly you may notice the completely polished surface appearance is identical to the raw foundry finish of the Tuttle mount) Hoping the H2So4 tank that looks completely black will settle out overnight so I can salvage most of it otherwise you might see some cheap acid on the sell pages soon.
Moral of story: do sand finish as best as possible but do not skip desmut. Next fin in the queue is the 18. This time will desmut + organic dye
Photos below of original fin 11 months and many km on (the dye should only be where the anodising worked), polished 24 before anodising, finger paint after harden, finished fin, dirty H2SO4 tank
Select to expand quoteFlex2 said..
Had the pleasure of sailing with the Fangman a few weeks ago on his home turf. As nearly always, was sailing with my first Fangy fin22. The one I butchered anodising 11 months ago. First time though the master Fangy checking it out. Despite a lot of distance he reckoned it was holding out very well. ( I haven't calculated exact distance logged on this fin but it must be in the order of 4000km. Mostly in weedy abrasive conditions and lots of dredging....
Oh Snap Flex, after seeing your fin I was so impressed I am now working on my own set up. Thus far I have gone the Sodium Bisulphate and Aluminium cathodes method for anodising bath. My kick arse 30v 30A power supply is still on a camel somewhere on the Nullabor, but I have been mucking about 'electropolishing' with phosphoric acid + sodium bisulphate brew and a battery charger. This has got me a good etch and easy de-smut process. From what I have read/found out so far, acid etch is better than caustic etch on cast aluminium alloys.
Electropolish at low amps blows off the crap on the surface and attacks the grain boundaries to give the cool etching patterns. Higher amps/area should actually polish the aluminium, but I will wait and see on that one.
Cast aluminium alloy has higher amounts of silica and magnesium and is hard to get uniform results as a result - the silica ( I think it is the black sh!t)) particularly is probably the reason the commercial anodisers didn't want to do the fins way back.
I am hoping to achieve a pseudo Type III Hard anodised surface, but until I get my power source, I must admit it's just been quite fun watching the effect of different acid strengths/mix/times. I will take some photos when fully set up and post here as well.
If you find a cheap source of phosphoric acid 85% for my electropolishing bath, pls let me know (best I have seen is about $25litre and ideally I need another 20 litres:-(
Nice one Fangman, electro polishing sounds like fun. I might try the caustic bath once more as is far cheaper and simpler solution.
Cheapest 85% Phosphoric acid I can find is $210 + GST for 20 litre. $160 + GST for 10 litre. It gets significant cheaper per litre to buy 200 or 1000 litres. Supplier is "All Chemical" in Malaga allchemical.com.au/shop/phosphoric-acid-85/ Delivery is $60+ as DG but can pick up for free. Its where I got my Sulphuric acid from.
My acid bath sort of settled overnight so will try the FF18 with that.
Set up costs so far: DC Power supply can be battery/charger, but if you want a bit more control of the process then a dedicated power supply is required. Probably around $650 to get enough grunt and control. (Ideally you want to be able to apply 10-15 amps per 1000 cm^2 surface area depending on finish desired)
The chemicals can add up to a few $. Happily most of it can be bought at Bunnings or a Pool Shop. The Sodium-Bisulphate ( alternative to Sulphuric Acid) is $46 for 6 kgs which will make up 30litres or so depending on the required concentration . Caustic is $8 for a tub. Phosphoric acid from my local brewer $140. (Flex's supplier in the post above is a cheaper option) Degreaser and Desmut depending on technique used can be as simple as Gumption or Detergent. I have a high quality reverse osmosis system for autoclaves that produces very, very low conductivity water so the 100litres of de-ionised water required for the acid baths and rinsing baths was no cost. If you had to buy this I guess it would be a few $ too. I am not colouring post anodising as I am trying to get a 'hard coat' anodised layer, but dyes are cheap. Low temp post anodising sealant $40 ish.
Buckets/tubs/Esky will suffice , but they need to be big enough to get a ratio of ideally 15g of aluminium per litre. Scrap Aluminium( for anodising) and Stainless( for electropolishing) for cathodes I had lying around the place, but I guess you could score most of it a salvage yard for not much.
An aquarium bubbler to agitate the solutions $10 on Gumtree. I use my tool air compressor and just bleed a gentle air flow into the tubs to keep them stirred.
Other stuff: The next level sophistication requires immersion heaters and coolers to change bath temperature as required for each technique. Obviously with a heater and plastic tubs you have to be careful. Pumping high current into the baths for long periods will warm them up. This good for electropolishing, and not good for hard anodising. Plastic freezer ice packs to drop the temp is simple and cheap.
A bit of Bicarb for splash protection/wash is a good idea. Gloves/Boots/Eye wear etc also.
These guys sell most of the stuff and you can get a good idea of costs from their web site. However my experience with them so far has been totally underwhelming:
www.caswellplating.com.au
So we can have a yellow Fangy that glistens in the sun like a gold tooth .?
Titanium nitride ?
Select to expand quoteImax1 said..
So we can have a yellow Fangy that glistens in the sun like a gold tooth .?
Titanium nitride ?
Dunno Cap'n Feathersword! From what I have read; Type III - Hard Anodising, which is what I am aiming for, does not pick up dye very well because the anodic pore is very small. It's left 'clear' and is typically dark grey in appearance. Black is the most commonly used dye colour with Type III.
Type II anodising( which is probably what I will get) holds colour better because the pore has a wider diameter. However the amount of silica and magnesium in casting aluminium alloys causes mischief with the formation of the anodised layer and so you end up with spots that hold more dye than others, and a blotchy non uniform appearance. Methinks there is lots of fun to be had experimenting, but I will just let Flex get a bit further along the learning curve first and hopefully I will then learn what not to do.
In the interest of doing an apples to oranges comparison (anodising is supposedly all about surface finish) and Fangman throwing down the challenge with his fancy Phosphoric Polish and big words high tech stuff..... I remembered whist decanting my contaminated acid from yesterday (lost only 500ml!) I'd bought some high grit sandpaper for some other project.
After a few hrs searching, I found the stash and proceeded to finish one side of the FF18 to 7000 grit. The sun was shining and it was kinda fun taking metal polish this far. Oddly the grain structure of the Al shows clearly at 1200 grit but slowly disappears for above grit. Right (starboard?) side of fin is finished to 7000 (first photo), other side is maybe 1200 grit (probably can do better) Yes, there is still porosity but some is never ending....will chuck this in the caustic bath, ano and dye tank tomorrow. Will the extra work with surface finish make any difference? Thinking I will skip polish step as can't find grit size of polish I was using. Standby for another exciting episode...
