[seanc]

Greg:

Yes Sean my bath temp was too high. I set it around 112F as per the Caswell manual. Speaking of that manual...is it just me or are many of the instructions out to lunch?

I only have the 2002 manual, so don't what the newer manuals say. My old manual did have some errors, but I thought they would have been corrected by now.

Does your manual cover both the new & original formulas? I know the new formula requires the higher 110º temp.

I mean it says that copy cad plates at about 1 amp per 40 sq" and this is way off.

I think that figure was simply based upon the power brick they supplied in the original kit. It was rated 1.5 volts & 300 mA, and was supposed to be good for 12 sq-in. So if you divide 300 by 12, you get 25 mA/sq-in, which scales up to 1 amp per 40".

BUT, in actual use, that power brick supplied nearly 800 mA, at @ 0.4 volts. 800 ÷ 12 = 67 mA/sq-in, which is toward the lower end of the useful range.

the temp controller that comes in the kit won't even go that low.

Turn it off when you get to 80º. Plate away. If/when the temp drops below 70º, turn it back on again for a while. The temp doesn't need to be precise.

I don't even use a heater in the summer, just run at ambient temp, which is usually 65-70º. In winter, if the bath is colder than 60, I use a cheap glass aquarium heater to bring it up to 70º.

The other thing that I have been wondering now is plating thickness.

Plate thickness depends on current density: higher density plates faster. At 100 mA/sq-in, it will plate 1 mil in about 40-45 minitues.

The NEW formula plates 1 mil in 20 minutes.

Apparantly yellow chromate needs a minimum of .001" to work and I can say that some of the pieces that I chromated were plated for only 10 minutes or so and they turned out excellent!

Yeah, I don't understand that requirement. As far as I know, the chromate only penetrates down a few surface molecules, so real thick plate shouldn't be needed.

I've done many pieces that were only .25-.5 mil, and they chromated nicely.

I checked the wiper motor housing and it is 2.5" deep with a diameter of 3.25" and yes the inside was fully taped off with electrical tape.

Well, that comes out to nearly 34 sq-in. 3 amps should have been enough current, but your anodes are smaller than what I would use as a minimum.

I think they are 4x8 but I'm not a 100% sure.

That's what mine were, cut into two 8x2 strips, gives 32 sq-in ( I do NOT count the side pushed up against the barrel wall). In my tank I had about 2" of each anode above the bath, so immersed area was only 24". Wasn't enough for a 36" piece.

If you turned the anodes on edge, so both surfaces were exposed in the bath, then it might be enough. Problem is, the surface of the part closest to the edge of the anode will get most of the plating current. You'd have to keep rotating the part to get even exposure.

I took the time to try and figure out the area of the largest item I should ever have to plate and it works out to 167 sq". Using the NEW solution what size power supply would you recommend for that size of a part.

The new formula calls for 140 mA/sq-in, so 167 x .140 = 21.98 amps! a 20 amp supply would give you 120 mA/sq-in. I would guess that the new formula would work at that density, but I have not actually tried it. I might try to run a few tests on it, see where the upper/lower range falls in.

Sean