Tank Size

[saintrich]

Here is a photo of my set up that I’m working on.
It is 14x6x5 ½ deep.
Right now all I need to do is one rifle receiver.
There is only one anodizing company her in St, Louis and they don’t do rifle receivers.
I don’t mind doing it my self (I think its fun).
I have been on other sites and they say all you need is a 12v battery or battery charger to do a good job, and they have photos to show.
I have anodized in the past with just a 12v battery charger.
They where slot car tools that I machined .And they came out looking good.
With the receiver I have close tolerances, so I don’t want to make any mistakes.
After reading here I'm scared of messing up.
Here on this site you all get into more detail, more precise.
I have limited space, so keeping in mind the formula 720 rule and surface area.
Is my tank size going to work for me?
Any help would be great, Rich

[dmiom]

hi Rich,

Your tank and aeration looks great, and not many would have such neat mitre joints! Your tank may well just be big enough for now (not certain of dimensions for your receiver) so following are general comments

In terms of sizing:

1. You need the cathode (preferrably lead sheet) in there now; and I would have the lead against the tank walls and across the bottom, and the aeration pipes inboard of / above the lead. If you can, cathode area facing the workpiece (i.e. ignoring the face against the plastic of the tank) ideally wants to be 2x or 3x the SA of your workpiece.
2. In terms of cathode disposition, try to get around the tank as much as you can. Its not quite like a sun-tanning-lamp, but you can get shadows.
3. You need room to hang the workpiece and good rule of thumb is that it should be 2" to 3" from any cathode and ideally at least 1" and preferrably 2" below the surface to get even anodising.
4. You may also need to have one or more glass/pyrex acquarium heaters to get the tank up to LCD starting temp (68F); and you also need to consider how you'll stop it getting too hot (70F is a good maximum for LCD method)

Dave

[acidrain]

The tank looks good, but I would be concerned with how you are going to control the amps without a CC power source.
It's possible to use a variable ceiling fan controller inline between the wall outlet and the battery chatger, but you'll need to accurately measure the amps (to .1 decimal place), and constantly monitor and control the output.
At the voltages a battery charger can supply, I would ano at 4.5 amps per sq. ft., and ano to 1 mil.
Before anodizing the receiver, I would practice on scraps first.

[saintrich]

I forgot to mention that I do have a plating power supply.
It is an older one, I don't remimber the amps or voltage off hand.

[dmiom]

I forgot to mention that I do have a plating power supply.
It is an older one, I don't remimber the amps or voltage off hand.

hi Rich,

It would be worth checking out its abilities before you rely on it. What you need for the LCD anodising method is a power supply that can work in constant current mode; deliver enough amps to run at your chosen density (calculated at say 4.5 - 6 ASF); and have enough voltage capacity to be able to push that through (the online 720 rule calculator will give an indication of the likely max voltage you may see - and you need a bit of headroom above that).

Some plating supplies are only constant voltage, rather than constant current - so not really suitable for un-attended use in the LCD method; and some plating techniques only require a relatively low voltage and max out at maybe 10 or 12 volts. If you are anodising at a typical LCD rate of 6 ASF then you can see perhaps 15v (or even a bit more) needed to push that current through the tank.

All I would advise is to check - it may be suitable but if it has a plating heritage it may not be as suitable. If it is constant-current capable, but has a less-than-ideal voltage range, you can drop the current density a little so the voltage doesn't max-out (although beware of dropping it too low as the acidic dissolution will be eating the anodise layer away as fast as its being created).

.... also, it does all seem a lot of hassle at times, but once you're tooled up, if you follow the Caswell LCD instructions, use the right chemicals and keep your process tanks at the right temperature, use the right current settings, are scrupulously clean, rack carefully and watch the timing, you can produce really good and consistent results - have fun !

Dave