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Zeeflyboy
07-08-2017, 08:08 PM
Hi guys,

I've been doing my research on anodising and while there are some guides on cobbled together systems using lead acid chargers and dimmer switches, it seems like the message is that the most important part for consistent results at home is using a good constant current power supply.

However, the amperage requirement for reasonable sized parts (around 2-3ft^2 in my case) makes it quite hard to find a reasonably priced supply and I don't seem to see many recommendations in all the various blogs/forum posts.

To that end, just wondering if anyone had come across a supply they could recommend? Using the LCD method described by caldwell, it seems they talk about 4.5amps per sq ft so really I'd be looking at a supply capable of around 20 amps

I did come across this, which might be suitable... while its not crazy expensive it's not pocket change either and I really have no idea if this is the sort of supply I need. https://www.reichelt.com/gb/en/?LANGUAGE=EN&CTYPE=0&MWSTFREE=0&CCOUNTRY=447&ARTICLE=146018&PROVID=2788&wt_guka=22596711737_79177291337&PROVID=2788&gclid=Cj0KCQjwn6DMBRC0ARIsAHZtCeMzr3KLl7SMipNN4AqQ UG2LUJGdzhlwh6-Q2yNt3t-koR8mUNm7k3MaAkl2EALw_wcB


Alternatively I have a rather powerful PSU that I bought a while back to use for my RC charger, capable of 2000w and 12v or 24v output. I believe it is basically two pc power supplies combined, but of course I would need some way to turn that into a constant current system... and I'm largely an electrical dunce. would my rc charger (two 500w outputs, can do lead acid up to 24v in the options) be suitable or is the clever charge circuitry going to get in the way?

Any advice would be gratefully received!

Zeeflyboy
07-08-2017, 09:42 PM
alternatively, this one is a bit cheaper...

15v should be sufficient? Allows up to 6amps/sqft according to the 720 calcs.... any thoughts on whether it is desirable to be able to do more than that?

https://www.reichelt.com/gb/en/?LANGUAGE=EN&CTYPE=0&MWSTFREE=0&CCOUNTRY=447&ARTICLE=110539&PROVID=2788&wt_guka=22596716177_79177295777&PROVID=2788&gclid=Cj0KCQjwn6DMBRC0ARIsAHZtCeMzClCJWKBXELsdbM6Z tjDblfmB1tK1Y253OaaUTPniyVVMWFmdkyQaAlKfEALw_wcB

m_c
07-08-2017, 10:21 PM
Something like what you've linked looks good.

Alternatively, have a search over on the EEVblog forum, as I'm sure I've read some posts on there about constant current supplies (I've not been on there for a good while, so I may be getting confused with somewhere else!).
I'm sure there's plenty constant current schematics around, but when you get to that amount of current, they have to be well designed to avoid releasing magic smoke.

Zeeflyboy
13-08-2017, 03:12 PM
Thanks for that, I'll have a look over there but since you say one of those I linked is suitable I will probably go for a proper retail unit rather than try building my own.

Cheers

Jonathan
13-08-2017, 07:50 PM
One of these:

https://www.aliexpress.com/store/product/RD-DPS5020-Constant-Voltage-current-Step-down-communication-digital-Power-Supply-buck-Voltage-converter-LCD-voltmeter/923042_32821185351.html?spm=2114.12010612.0.0.2238 8c28Yvk2a1

With a suitable transformer - or batteries if you want.

Housed in a case, if you want ...

22568

Boyan Silyavski
13-08-2017, 08:30 PM
I was in that doubt before some time.

Maas HCS 3400 (http://www.maas-elektronik.de/MAAS-HCS-3400-Schaltnetzteil-40-Ampere.2.html) 1-15V, 0-40A Bench Power Supply was the one i bought and i believe is a best heavy duty budget one that could cover quite big parts like alloy wheels and so on. Its well tested and serves for the purpose, German quality control , its Chinese but bit better than no name crap.

Clive S
13-08-2017, 08:36 PM
I was in that doubt before some time.

Maas HCS 3400 (http://www.maas-elektronik.de/MAAS-HCS-3400-Schaltnetzteil-40-Ampere.2.html) 1-15V, 0-40A Bench Power Supply was the one i bought and i believe is a best heavy duty budget one that could cover quite big parts like alloy wheels and so on. Its well tested and serves for the purpose, German quality control , its Chinese but bit better than no name crap.

The one Jonathan linked to is 0-50V yours is 0-15v but it does need an external supply

Boyan Silyavski
13-08-2017, 09:53 PM
The one Jonathan linked to is 0-50V yours is 0-15v but it does need an external supply

Anodizing needs Amps not Voltage . Its perfect for the purpose, i wouldn't have recommended or bought it if it was the wrong one...

Now if he was anodizing Titanium or messing with plating, a better supply will be the 3602, which is 0-30VDc 0-30A. And yes, thats maybe the best Lab PSu to have at home for multipurpose, but its quite more expensive.

There are other cheaper possibilities:

http://www.ebay.es/itm/MLINK-KPS3030DA-30V-30A-REGULATED-ADJUSTABLE-DC-POWER-SUPPLY-DIGITAL-DISPLAY-/252536278070?hash=item3acc55cc36:g:BT8AAOSwgmJX1p2 V

https://www.ercmarket.com/digital-lab-switching-power-supply-with-regulated-mode-30v-20a-ps3020.html

https://www.ercmarket.com/maas-power-supply-1-30v-dc-0-30-a.html

Clive S
13-08-2017, 11:45 PM
Anodizing needs Amps not Voltage I don't think you can have one without the other:cower:

Zeeflyboy
14-08-2017, 01:52 PM
0-15 volts is ok for up to about 6amps/square foot which is fine for the LCD method it seems, if going with 6asf that allows some fairly large pieces to be done with a 40 amp power supply.

30v would allow you to run at 12amps/sq foot, so you could get parts done more quickly but the power requirements quickly get out of hand for anything other than small to medium sized parts, but it is twice as fast.

I think 0-30v and 40 or so amps would be ideal, my largest part so far is about 2.6 sq/ft so at 12 asf would require 32 amps but I haven't seen any capable of that sort of power within a reasonable price range. The closest is that first link at 0-30v and 30 amps. I'm not doing it on a production basis so it's not a huge problem to run at 15v and 6 amps/sq ft and just accept that it'll take 2 hrs for a mil rather than 1 hour.

Jonathan - that looks interesting, I'll do some reading up and looking around at your link a bit more closer later thanks. The amps of the one you linked won't be sufficient to do the larger parts at 12 amps/sq foot but maybe I could just drop down to 6amps/sq foot for the larger pieces and it still leaves me the option to run at a higher voltage to do smaller pieces more quickly at 12 amps/sq ft.

Thanks for all the input guys!

Boyan Silyavski
14-08-2017, 03:01 PM
40AMP 15vdc PSU will be good for ~7 square foot at 6Amp/Ft² density which is the recommended density for home scenario. Here (http://ndhsubmersiblescience.com/ano/720rule.html)is the calculator which i assume you know of, but anyway i will pass the link. I have tested it many times and it works perfectly.

For me price wise it was the perfect one PSU, having in mind i bought the acid in 20L

Clive S
14-08-2017, 03:19 PM
For an experiment could you just use a standard lead acid car battery 3 sq/f would take 3 hours at 12A

Boyan Silyavski
14-08-2017, 07:06 PM
For an experiment could you just use a standard lead acid car battery 3 sq/f would take 3 hours at 12A

I used that while waiting for my PSU. The thing is that there are certain times where you have to take certain steps and there is nothing better watching at the display what's happening with the Amp draw. In fact you have to limit it at the beginning, hence the need for Volt Amp separate control. I guess with and digital amp meter you could do that monitoring. With the proper PSU and using the calculator above, i was able to reach desired anodizing thickness at first try.

Zeeflyboy
14-08-2017, 09:06 PM
I used that while waiting for my PSU. The thing is that there are certain times where you have to take certain steps and there is nothing better watching at the display what's happening with the Amp draw. In fact you have to limit it at the beginning, hence the need for Volt Amp separate control. I guess with and digital amp meter you could do that monitoring. With the proper PSU and using the calculator above, i was able to reach desired anodizing thickness at first try.
I'm certainly no expert, but from my reading it seems the key to consistent results (especially when dying the parts after) is to use constant current from a proper power supply.

Have you guys ever found a source for 6063 T6 aluminium for cathodes or do you just use lead and be done with it? I can't find 6063 T6 in any decent size.

Boyan Silyavski
15-08-2017, 08:56 AM
I'm certainly no expert, but from my reading it seems the key to consistent results (especially when dying the parts after) is to use constant current from a proper power supply.

The constant current is to limit as i said to a certain current the current draw. Then current starts to drop at a certain time, when certain thickness is achieved, hence you can judge the thickness by the current draw. You can not give more current than it could take when there is the anodizing layer already formed


Have you guys ever found a source for 6063 T6 aluminium for cathodes or do you just use lead and be done with it? I can't find 6063 T6 in any decent size.

I don't know how big you are going to make your tank but here is some friendly advice:

1. Dont be cheap on the container and if possible buy proper anodizing container. make sure it's from the right plastic. And keep the rest in dark place inside.

I used a plastic one from chinese shop which i deemed good at the time and it worked well. In fact i bought 2 of them , transparent, and one was fit inside the other as extra security.

That did not stop the original 20l plastic container to brake in my hands half full with acid when i was moving house next year and 10l of acid to fall and splash from 1 meter around me. Luckily my reaction was fast and as i always use full face protector , working trousers and protective boots around acids and when welding, so i got without a scratch. The plastic have deteriorated which is very strange, but i think that was result from me leaving it outside, though it was covered. The chinese transparent boxes were ok though

2. Junkyard is your best place to go and find aluminum sheet. Any sheet will work. I used 1mm sheet with great results. If anodized, just use the other type of acid that you will use for cleaning your pieces to wash away the anodizing. Do the tank properly and use aeration, temp monitoring. If you do the tank big enough there will be no need for temp control, though if you are serious enough its not a big deal to DIY a way to cool the tank. No need to say that you must heat it using fish tank heater to the proper temperature.

3. If there is a way to do all that outside open air beneath a shelter or sth, that's the best way. It stinks and is dangerous for health. I wear respirator with proper filter / which is different from normal painting filter/ . Maybe you know summer here in Spain, every time i was anodizing i was dressed like a nuclear response team, sweating like a pig, but health is quite more important. My tank was about 70x50x50cm and i dont see how sb will do that inside if there is not an extractor on top of it. Anyway, is best to use an extractor even outside so fumes go somewhere else , hopefully not your neighbours bedroom window


4. Check all that works correctly with water before using actual acid in the tank. Do yourself a favor and buy a water osmosis sytem as you will need a lot of water, so buying distilled water will not do. Even for small projects.

Zeeflyboy
15-08-2017, 04:00 PM
The current dropping off is doing a constant voltage technique though no? You seem to be describing constant voltage but with a limit on the current.

My understanding is that the constant current technique tries to maintain whatever current you have set by raising the voltage. So one takes the sq ft of the part, multiply by 6 (if using 6asf) and then set that result in the power supply, which will then slowly raise the voltage as necessary to maintain that current. Using the 720 calculator you can then determine that at 6asf for example, the final voltage will be 15v and it will take 2hrs for a 1mil layer.

Thanks for all the tips - I believe I should be using a polypropylene tank, my slight problem is that my larger parts are quite long. I found a suitable polypropylene container in home base, but to get enough length its a 60L tub, which is a lot of acid, heavy and a big thing to store when it's far wider than needed in reality. I could get away with something much thinner, but never seen anything suitable and not sure how I would go about building my own tank.

Would a fish tank work? You can get those fairly long and thin, but not sure about the sealant they use and the acid.

Clive S
15-08-2017, 05:38 PM
If it is only for one long part you could use some heavy duty membrane (think dpc under concrete) and make a temp. trough with timber to support it (outside of course). Or dig a channel in the garden to support it

Boyan Silyavski
15-08-2017, 06:27 PM
Long pipe cut along in half ? like the ones they use now for drainage or water, they are from some heavy duty PP or PE. Any construction site will have pieces thrown

Zeeflyboy
17-08-2017, 06:30 PM
Decided just to buy an 80L polypropylene crate.... Internal dimensions are about 600x400x400ish mm so will fit the longest parts I currently plan to use and means I can do batches of smaller parts to save time.

It's wider than I needed, but I have designed a little PVC pipe cooling system which will eat up some of the volume... will just run cold water through it to keep the tub cool. Whether or not it's necessary really, probably not, but at least it takes a few litres of displacement out of the tank which is a few less litres of acid to deal with!

Cheers for the assistance chaps