Anodizing Bench - starting my own...

[aeroHAWK]

I joined this forum about six months ago because I saw Tom's anodizing bench thread. I had planned on setting up my own anodizing line, and Tom did such a great job of explaining and showing how to do it, I joined the forum and began setting thing up. I've done some work in that regard, so I figured I had better post some progress....

I'm using smaller tanks than Tom did. Mine are two gallon instead of five. Plus I'm using picnic coolers for the heated baths. The ones I found are Igloo 9 quart coolers.

I made a manifold for pumping air bubbles into the tank to keep it "stirred".

Since the acid bath warms while anodizing, I opted for a larger tank for the increased thermal mass (and therefore slower heating). It is in the four gallon range, but since it isn't insulated like the coolers, it doesn't take up a lot more room.

I haven't yet made a bench nor have I gotten all the parts together to have my anodizing line complete. However, I have clear anodized over 50 parts of various sizes, with good success. And of course, I learned A LOT in doing so.

The most important thing I learned is to use a Constant Current power supply. I started with an old manual automobile battery charger. Fortunately it died (although it didn't feel fortunate at the time). The failure had me scrambling to find an alternative since I had a job to finish and I was behind schedule.

The parts I anodize are not large so I don't need a huge power supply. I had a surplus Laptop charger/power supply lying around so I connected it to a Current Control module I got on eBay. This what the charger looks like:

I was able to finish the job, but more importantly, the Constant Current module made a huge difference! The Laptop charger is 19 volts and anodizing in my tanks needs 13 - 16 volts (this will vary with the size of the parts, temperature, pH, cathode, etc.), the Constant Current module is a "Buck" (or step down) converter. It has a digital display for both Amps and Volts, and looks like this:

The Laptop charger is only 65 watts, and I would like a little more "headroom" for the larger parts I may anodize, I am "upgrading" to a Desktop PC power supply. It is really old (from a 386) so it is still limited but 120 watts at 12 volts is still an upgrade....

Since it is 12 volts, the Constant Current module needs to be a "Boost" (or step up) converter.

The one I got on eBay doesn't have the Amps/Volts display so I also got a separate display from eBay.

I'm currently in the process of putting it all in an enclosure. The module uses small 10-turn trimmer pots to adjust the current and voltage, so I am planning on removing them and wiring in a standard panel mounted pot for easier use.

Oh, I almost forgot... here is a sample of the anodizing I have done:

[Bluechip]

I see no pics ??? Just the dreaded black cross.

Dave

[John Rudd]

 :mmr:nice pics....

Are you going to add some colour to your items?.....Blue perhaps? 

[DMIOM]

hi Aero,

good to see your setup developing.

Couple of quick thoughts :

Glad to see you're going with constant current, that's the way to get reliable, repeatable small-scale results.

Your actual anodising tank - you've got your aerating pipes right in the corner - ideal situation to avoid shadows is as close as you can to 360 degree surrounding with the cathode - lead flashing sheet or similar. I would fit the lead lining first and then the pipes on top.  Bubbling on its own may not be enough - you may need pumped circulation as well...   Note your comments on larger liquid mass reducing probs with heat build - but remember you may need to inject some heat to start with as well.

Talking of heat, note you're using coolers - what temp will they safely stand? especially boiling sealant.

You may find it interesting to read this MadModder thread on anodising (p.s. that's spelt the way the rest of the world does so if you searched anodizing you may have missed that thread!    )

Dave

[Arbalist]

Nice setup, your results look good.  The last anodising I had done was what they called "hard anodising" which is I think done the same way except the acid solution is kept very cold? The results were good anyway.

[aeroHAWK]

Are you going to add some colour to your items?.....Blue perhaps? 

Yes, I have dyes for black, blue, red, and yellow. Since the job I showed, didn't require color, I haven't yet set up those tanks. I need to make the bubble manifold and work out the heating (the dyes need to be at 140 deg. F). I have heaters that look like this:

I'm still working on the temperature controller....

Your actual anodising tank - you've got your aerating pipes right in the corner - ideal situation to avoid shadows is as close as you can to 360 degree surrounding with the cathode - lead flashing sheet or similar. I would fit the lead lining first and then the pipes on top.  Bubbling on its own may not be enough - you may need pumped circulation as well...   Note your comments on larger liquid mass reducing probs with heat build - but remember you may need to inject some heat to start with as well.

Good points Dave. Thanks for the suggestions. Your point about the cathode being 360 degrees has me thinking of making a new one. The bubbles seem to be working well, so it doesn't look like a pump is needed - it's not a large tank. Also, I keep my shop heated year round so the acid tank stays a good temperature.

Talking of heat, note you're using coolers - what temp will they safely stand? especially boiling sealant.

Another great point. I neglected to show that I'm using a stainless steel pan for the sealant tank...

(p.s. that's spelt the way the rest of the world does so if you searched anodizing you may have missed that thread!    )

Thanks Dave, I did notice that we Yankees tend to spell things a little differently. I'm still getting used to the spelling of "colour" also (my spell checker doesn't like it).

The last anodising I had done was what they called "hard anodising" which is I think done the same way except the acid solution is kept very cold?

I have considered this too. I found some additive that makes it so it doesn't have to be so cold.

[Arbalist]

I used to belong to an Air Rifle club and one of the other members worked at a metal finishing company. Some of the Anodised parts he brought in looked stunning, many of them were multi coloured. One example was a part that was mainly blue but had a random silver "thread" running all over it. Some other items were red and blue. I didn't think to ask how it was done I think it may have involved a wax resist?

[aeroHAWK]

One example was a part that was mainly blue but had a random silver "thread" running all over it.

It may be what I understand is "splash" anodizing. I uses a masking solution and bleach to remove unwanted die. Here's a YouTube video:

[DMIOM]

Thanks for extra pics Aero. One thing to watch with those heaters is that you don't get the dye too hot, even in just one location. You can (don't ask me how I know!) get the dye too hot, and even just one hot spot can cause a problem. You would think, in general 'chemical' terms, hotter is usually faster which can often be better. The problem is that if the dye is too hot, you can get premature sealing of the oxide matrix you've carefully grown in the ano tank - you may just get a bit of dye in the top of the matrix and it'll "self seal" - but it won't be full-depth, can be particularly noticeable on black dyes where it will look paler and potentially longer-term wear unevenly.

Re circulation etc. in the actual ano tank - your pipes look to have a row of holes on the top. That will give a rising curtain at each side, and will induce some circulation; but depending on the geometry of the part, it may not be enough, particularly if you've got areas where bubbles can be trapped. The actual ano process out-gasses, and if those micro-bubbles get trapped they act as a localised insulator, so you can get an un-even depth of matrix and hence uneven colour if you're dying it. If you're going to stick with just bubbling then you may want to (a) have some holes at varying angles, and (b) consider having some transverse rows across the floor of the tank.  I have pumped circulation through a chiller, but also bubble pipes every 2 inches.

There are a few more points (which you may already know about!) in that thread I linked to earlier.

Dave

[bertie_bassett]

if I remember rightly, for multi coloured parts you dye the whole thing with the lighter colour, then use bleach to clean off the dye where required, and re colour those areas.  followed by sealing with steam.

might be wrong though!

[aeroHAWK]

The problem is that if the dye is too hot, you can get premature sealing of the oxide matrix

Thanks Dave, this is something I knew about, but it is good to be reminded. There are so many little things that can sneak up....

If you're going to stick with just bubbling then you may want to (a) have some holes at varying angles, and (b) consider having some transverse rows across the floor of the tank.  I have pumped circulation through a chiller, but also bubble pipes every 2 inches.

Your comments seem to put more attention on something I have been being casual about. So thank you, I'll make some changes. One thing I found was that the manifold would fill with solution when not in use, and it would take a lot of air to clear it out and produce bubbles from all the holes. I have been planning on remaking the pipes with much smaller holes to get higher air pressure. I'm thinking this will help evacuate the manifold better. I'll put holes in different places when I do it.

[Will_D]

I'm still working on the temperature controller....

Just search e-pray for STC-1000!

Can be got for about a tenner from China, 20 from the UK.

Basically its contoller with 2 x 10 amp realys that can switch heaters or coolers. We use them all the time in th ehomebrewing world

[Arbalist]

That's probably it aerohawk, although the stuff I've seen looked a lot better than that demo. 

[aeroHAWK]

Just search e-pray for STC-1000!

WOW! Will, Thanks! That's great.

That's probably it aerohawk, although the stuff I've seen looked a lot better than that demo. 

I 'll bet... the video shows a good method. The execution of that method is something else....

[aeroHAWK]

Dave,

Well, you've got me thinking. I doesn't look difficult or expensive to use a submersible pump for circulation. It seems it may be more effective than bubbles. Since my tanks are small, I assume it doesn't take much of a pump. I'm looking at this:

http://www.ebay.com/itm/Ultra-quiet-Submersible-DC12V-Micro-Brushless-Motor-Oil-Water-Acid-Pump-0-60-US-/201232368198?pt=LH_DefaultDomain_0&hash=item2eda624246

Also, do you have any suggestions for tricks to get good circulation? I am also looking at using it in my detergent tank, since bubbles stir up a lot of suds.

[Brass_Machine]

Very nice. I am dying to do this. Any chance on doing a "how to" on the actual anodizing process?

Eric

[aeroHAWK]

Any chance on doing a "how to" on the actual anodizing process?

Yes Eric, I'd be happy to. Although, it may be a while before I have all my ducks in a row.

In the meantime, you should watch the video Tom did using his anodizing bench. You can watch it here:

[Jonny]

Best of luck I gave up on it 10 yrs ago really hit and miss over 3yrs.

Did have a twin digi psu but kept packing up so went for the analogue Maplin one Tom uses at 14.4v.

One major problem I used to have was electrical breakdown. No way could use wire wedged in to a part, best had was around 5 mins as anodic layer built up between the two joints. Ended up filing anodising off aluminium 6082 and forcefully wedging in to a hole. Pro anodisers use titanium sprung clips of various styles hence why theres always a scratch area.

Up to the last 10 years there was literally 5 sources of information on how to and they all told a vastly different story in every process often missing vital info. Done hard anodising twice.
Dyes were one concern, tried everything I could get my hands on eventually settling on a powder what the pros use. Fairly sure it was around 90 degrees any higher it sealed the parts or turned it maroon to brown. Used fish tank thermostatic heater, cheap.
Ampage used to drop within 2 mins of putting part in, something like 5" round drawed in excess of 6A, after 2 mins down to sub 2A.

Still got the small 1foot fish tank the 4 foot x16" high level one my nipper broke, gallons of 21% sulphuric escaped. Use one of two pros now but theyre stinging me £40 cash for a few parts or loose a vital part or even scrap the jobs sent in that took months to produce.

Last link above is called splash anodising no need to do what he did, pros just flick something across the part hence the term splash.