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I am using a potentiometer (not a rectifier)to control the current and my battery pack is made up of 10 AA nicads that have plenty of power
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10 AA nicads are more than enough current. Depending on the capacity of each battery, this should be somewhere in the range of 4-6 amp hours. You'll get some voltage drop across the potentiometer, but how much depends on how many ohms it's actually dialed in at.
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tried another set of nicads that had 3.7 volts but even that is too little according to your setup
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This depends on the potentiometer setting. If it's dialed to a fairly low resistance, it's plenty of voltage. Actual plating voltage across the anode/cathode is fairly low. You'll typically only get 0.5v to 1.2v, depending on the total size of the parts.
However, if your potentiometer setting is high, you'll be burning up too much power w/in the pot, it will incur a high voltage drop, so voltage at the anode/cathode might be low.
Don't measure voltage at the batteries. Measure voltage at the tank, across the anode/cathode. If it's less than 0.4v, then you're losing too much across the potentiometer, and you'll nee to raise the battery pack voltage.
If you check the "Sitcky" thread: ATTENTION SUCCESSFUL PLATERS - YOUR DATA NEEDED, I've posted some of my actual plating data:
http://www.caswellplating.com/bbs/viewtopic.php?t=3243
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I have been heating the solution to the recommended 110 degrees but your setup was at 65 degrees.
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I've heard reference to this temperature before, but don't know where it comes from. My manual (ver. 5), says 60-90 degrees. When I was having my problems, on suggestion I tried 110ยบ but that made things worse.
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I haven't been using an acid pickle because I didn't think I needed to
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If the parts are rust-free and really clean, you don't need it. The only time I use it is if there's going to be any delay between the degrease/clean step, and putting the part in the plating tank. eg, if you take a parts out of the SP (or whatever you use) degreaser, rinse it, and leave it set for a few minutes, it will form surface rust. So if I have a lot of small parts that I want plate at once, I drop each one in a 5% muriatic pickle after degreasing, just to keep them from surface rusting. Then when they're ALL clean and ready to go, one more rinse to get the acid off, and into the plating tank.
A mild sulphuric acid dip (1-2%, for a few seconds) is useful AFTER the parts are plated. The zinc electrolyte is brown, and plated parts come out w/a brownish film. This brownish color will remain on bright plated parts. The sulphuric acid dip removes the brown film and leaves the part all silver/gray.
You can see examples of this in the photos I've posted below. (check the "U-bolt" and "Large parts" sections). I used muriatic acid dips for these early plating runs, but am using sulphuric now. It comes out better.
http://www.hogheaven.com/hobby/plati...rts/index.html
Sean