Anodizer problem?

Will52100 · Dec 5, 2006

I finaly got ahold of a variac, 0-150v, and built an anodizer using Bob Warners plans, http://www.warnerknives.com/anodizer.htm

It works, but I am now blowing fuses in a second or less. The rectifier is rated at 6 amps, and the variac has a fuse between the output ac and the rectifier. The fuse that was in it when I got it seemed pretty heavy, lot heaver than 6 amps and worked for a while but then blew. I put a 6 amp fuse in and it blew almost imeadeatly.

I've wired it up temporarily like the first diagram, and use a cheap volt meter to check leads out till I'm satisfied everything works rite then I'll wire the volt meter in for a display. Also I tried a split hook out of ti, to hang the linners off of. Aparently that didn't make good contact, so light pressure with a screw driver made contact and the TSP solotion started boiling around the test piece, that's when things started blowing fuses. I tried gator cliping directly to the test piece and it too blew fuses pretty quik. I understand that the solution is suposed to boil? Also using a large mouth mason jar to hold solotion and anode and cathode, using plastic canvas to hold the ti cathode inplace.

What am I doing wrong? Do I need a heaver fuse going to the rectifier?

Thanks,

Will

David Wesner · Dec 6, 2006

Sounds like your set-up is similar to mine Will. I blew fuses one day trying to anodize a piece of Ti that was as big or bigger than my cathode,increasing the size of the cathode took care of the problem. Are you hooked up to your bridge rectifier the correct way.I made that mistake too once (fact of the matter is I've made most every mistake at everything I've done so I'm "experienced" ). I learn everything the hard way

Will52100 · Dec 6, 2006

The rectifier is set up rite, I'm wondering if I need to use less TSP in the solotion? I used tap water as I didn't have distilled on hand, got some with some more fuses today, I'll play with it some tonight and see what happens.

btboone · Dec 6, 2006

It doesn't take much TSP. That could very well be the problem. The piece doesn't boil for me most of the time unless my solution needs to be changed out or the piece has contamination from a wire wheel or something. I anodize 6/4 titanium rings, so have a small setup. I use a stainless cup and a niobium wire to hold the rings.

Will52100 · Dec 6, 2006

Got it figured out. I used distilled water and a lot less TSP and instead of running the voltage way up there found I can get nice colors in the 15-50v range.

Thanks

Frank Barron · Dec 6, 2006

Guys
What you were doing was shorting out the winding and drawing more current through the variac. IF you can boil the solution you conductivity is way too high. What I would suggest is that you go to an electronic store and buy a 100 ohm power resistor rated at 20 watts. Then put this in circuit between your variac output wire and your anode. This will limit the current to "safer" levels and the colouring time will be a little longer to work with.

FB

DAMNENG · Dec 6, 2006

Without seeing your setup, I can just guess what is going on. Ohms law says that voltage is equal to current multiplied by resistance, or rearranged current is equal to voltage divided by the resistance. It the case of the plating bath, the voltage appled to the piece to be anodized, and the resistance of the plating bath is used to determine current. If conducatnace of the bath is to high (conductance is the inverse of of resistance) too much current will be drawn and the fuses blow. To keep the voltage at the value needed to produce a chosen color, you don't want to put a resistor in series with the leads hooked to the bath.

I would suggest setting up the bath with an amp meter in series to determine the current and a volt meter across the bath leads to set the bath voltage at the level chosen for the color you want. Start off with just water in the bath, and sprinkle a little TSP in the bath as you watch the amp meter climb when the current gets up to where you want it, stop sprinkling the TSP. Remember the TSP won't disolve immediately, so there will be a time lag between adding the TSP and the current rising.

Jim Arbuckle

btboone · Dec 7, 2006

If you etch the titanium with MultiEtch to get the oxide off, the higher voltage colors are a lot cleaner. It's some acid from Reactive Metals that gets mixed with water and heated in a small Crock Pot. My teal at around 110 volts is usually muted; I think it's actually a combination of 2 colors interfering at once. It gets more gray if there's an oxide on the titanium before anodizing. It's very bright if I etch beforehand. I don't need to etch colors like bronze or blue since they are relatively low voltage colors.

Another thing I do is use a small paintbrush to wipe off any bubbles that are on the part as it's being anodized. Some of my rings have grooves cut in that hold bubbles. The brush works great to get rid of them. Obviously watch to be sure you don't short out the circuit when swiping at the part. I noticed that the anodizer described has no isolation transformer. It's a good idea to have one for some extra safety.