[sage]

The size of the parts I need to do is the only reason I'm moving up. I have a base plate for a model engine I'm building. It's 13x7" x 1/2 inch thick. It wouldn't fit in the small tank. I'm also crossing my fingers that the temp won't rise too much even in this larger tank. I'll keep the current down to acceptable time.
You could be right about the metal rod on the mixer, but I see the squirrel cage bits can be removed from the rod and I could easily replace the rod with a plastic one. It's really not under much torque stress at the 180rpm of the screwdriver. I consider the whole thing expendable at $8. It works so well it's worth a try though.

You mention 250k for the tank resistance. Something wrong there. From where to where did you measure that. Typically, the resistance is dependant on the size of the part and the resistance of the acid (distance through the acid to the part), but typical running resistance of the tank should be a few ohms or so. I was expecting higher resistance only because if I do a run of my usual small parts and put them in them in the middle of the larger tank the distance would be higher than my small tank. I'll probably fire the whole thing up for a trial tonight.
I also expect to have to replace the cathod really soon. I cobbled it out of aluminum flashing which I thought was thicker when I saw it on the role but it turns out to be only 10thou (.010") thick so it might disappear quickly. Once I'm past the two big parts for this project I can proabably return to my small tank.

Sage