Rig for Anodizing Pen Barrels?

[LadyTiger]

Hello, all. As part of my senior design project, we're making prototype aluminum fountain pens (10 total; 5 in one color and 5 in another). We want to anodize the pen's barrel, cap and a sealing end-piece such that all three pieces color match. The system that we're using belongs to the university machine shop, so I'm not sure of the details. I do know, however, that the anodizing "tank" was a medium-sized beer cooler in a former life.

Our stock is 6061 Al.

I've got several questions that I bet some of you can help answer:

1) Would it be possible to anodize all parts simultaneously and get them to color match that way? (Each piece has a very different size and surface area.)

2) We're thinking that the endpieces (which will friction fit into the bottom of the barrel) would be best anodized by drilling holes in a thin sheet of conductive metal and letting the endpieces sit in the holes. Is this a reasonable approach? Would a similar system using dowels be a good way of anodizing the caps and barrels?

3) If we were to sand-blast the pieces and anodize sans dye, would that give a nice slivery-white finish to the pieces?

Thanks for your help!

[acidrain]

Yes, you will want to ano all the parts at once for a good color match.
Your connection approach doesn't sound good... I would use Ti wire (if you can find it) and bend into a kind of inside clamp. Then it can be shoved into the barrels without blemishing the outside.
Calculate all of the surface areas, and multiply by your target CD for the required amps.
They should all turn out exactly the same as long as all the parts are the same alloy.
Instead of sand, use very fine glass beads to give a satin silvery finish... sand will embed contamanants.

[destroyer125]

Id use some .030 titanium rods. I have some laying around if your interested, feel free to PM me

[LadyTiger]

thanks for your replies! my group members vetoed the Ti wire (for silly reasons) and we will be using "steel paper clips" as recommended by the professor who runs the machine shop.

how should we connect the endpieces? they're essentially peg-shaped. will bent wire also work for them? (i'll try to remember to post some pics in a bit.)

[acidrain]

Ha ha, steel connector wires in sulfuric acid? I don't think so.
Aluminum wire will work, but any ferous metals will contaminate the acid and cause problems.
Let us know how things work out!

[snipescastle2]

Do as the guy's say, or you will have a mess on your hands and a lengthy lesson to learn. Ti wire or even a good, stiff aluminum wire would be best, I know they make MIG welding wire for aluminum that would be perfect for what you are trying to do, a roll costs about $25.00 to $30.00.
Ben

[destroyer125]

If your going to use paper clips, Id suggest going and buying some long gloves, You will need to grap your pen pieces out of the bottom of the tank.

[hurricaneracing]

Paper clips = bad idea. You can get a roll of aluminum wire from Home depot or maybe walmart it is used for electric fencing maybe a little less exspensive than the welding wire.

[LadyTiger]

Boy am I glad that I checked that idea with you folks! We have since found some Al wire that we're going to use.

Of course, the guys have this bright idea that we're going to hang the Al wire from an electrified copper rod so that we can more easily anodize multiply pens at once. Yet I suddenly suspect that this idea is another poor choice given that Al and Cu are pretty reactive...

On a different note, I've calculated that each pen will have roughly 0.144 sq-ft of surface area. Will a 12 V, 2 Amps power source be adequate for treating 5 pens (~.75 sq-ft) simultaneously? Alternatively, we have an 8 V, 3 Amp source that we could use.

We've cut some test blocks of 6061 Al slab that we're going to anodize in the morning using the 12V power source. I'll be sure to let you know how that works out.

[acidrain]

Sounds like a good choice of connection wire!
The aluminum to copper connection is not too bad as long as it is out of the acid.
You'll need to have a good solid connection... not just parts hanging on a hook. As the ano layers build (both the parts and the wires) you'll loose the connection (ano layer is an insulator). You'll see this as wires that take dye easily, but the parts do not.
The most common problem with beginners is loss of connection.
I would think the smaller PS would be adequate, but you really should be measuring the total surface area, and multiplying by your target CD to get the required amps. 6 amps per sq. ft. is a good CD (current density). At that CD, the time in the tank calcs out to 1-1/2 hrs for .75mil ano build.
Post some pics when you're done. I think you're well on your way now.