Newbie zinc plater with a power supply question

[robcar]

Aloha everyone. Just wanted to finally introduce myself and jump into the discussions. I have been wanting to do zinc plating on automotive restoration parts for some time now and recently purchased a 4.5 g Copy Cad and Zinc Plating Kit. I’ve been doing a lot of research and reading for a long time but I still have a lot of questions on my mind. I hope I can get some of them answered here. I still don’t have a power supply yet so that’s my next investment. I have been looking at some of the power supplies here but I also have a lead on a Grobet USA ProCraft 25 amp rectifier – “Precision built in the USA, continuous duty, solid state. Works by means of the powerstat control to produce desired voltage. All units have pilot lights and both DC ampmeter and voltmeter for measuring current under load.” I was wondering if this would be a good choice for zinc plating. Right now the largest parts I plan to plate are brake rotors and calipers. If anybody has an opinion/advice/experience with this or any other power supply I’d appreciate it.

[lcaswell]

That rectifier will be great for plating parts up to approx 170 sq in.

Zinc plating needs .14 amps per square inch.

[robcar]

Thanks Lance. Do you or anyone else know if this is a constant current or constant voltage PS or both? And does it have a current control? The owner doesn’t know much about it and this is what I have found out so far: “Precision-built in the USA, continuous-duty, solid-state electronic units with a range of power to handle all plating needs. Works by means of the powerstat control, to produce desired voltage. All units have pilot lights and both DC ampmeter and voltmeter for measuring current under load. All units come with a set of lead wires with alligator clamps and terminal lugs. 25 and 60 amp units can be used for electro-stripping.”
Specifications:
• 0 to 25 amps output, continuous duty
• 0 to 12 volts DC output
• Runs plating baths up to 5 gallon except for rhodium which is a 1 gallon maximum.
• Steel cabinet measures 13" W x 8" H x 8 1/2" D.
• Shipping weight of rectifier 20 lbs.
Please forgive me for my lack of knowledge but I am new to this and know very little about power supplies. From what I’ve read and found out so far a constant current rectifier is the best type of power supply for zinc plating correct? Correct me if I’m wrong but you want a PS with a current control to set the amps and the voltage will follow. Some PS don’t have a current control only a voltage control. This is not the ideal type of PS for zinc plating. The only information on the Grobet ProCraft 25 amp rectifier I found regarding control stated “Works by means of the powerstat control to produce desired voltage”. I am assuming that it has a voltage control and not a current control. If this is the case then it would not be ideal for zinc plating. But it also states “0 to 25 amps output, continuous duty.” Does this mean it does have current control? From the pictures I can see only one control knob on the unit and am not sure which one it is used for, voltage or current. I am heavily looking at and really want the SPC-9250 25 Amp Constant Current Rectifier. I know this is the ideal PS to get for my set up and it has a digital display for what I believe is more accurate settings but it is a little out of budget right now. I may be able to afford the used Grobet ProCraft right now to get me started right away if it has the right stuff and then upgrade to the SPC-9250 later when I can afford it. Any comments, opinions or advice?

[lcaswell]

We used to sell these units a long time ago. It's not constant current or voltage.

Current control is achieved by varying the voltage.

It's not the perfect power supply, but it will certainly get you going.

[GHudgens]

In my opinion, based on over 6 years experience with the old CopyCad bath, you do not need a constant voltage or constant current power supply. I have two differenct power supplies that I designed and built and they are unregulated power supplies. I control them with a Variac for one and a simple rhesostat for the other. I do filter the output to reduce ripple. I have found that once you set the current, it remains highly stable (assuming you are controlling your bath temperature). The current, once established remains constant and you do not need to control it other than the initial setup. I get excellent results from the CopyCad bath without using the brightener (which doesn't work).

Jerry Hudgens

[robcar]

Thanks again Lance. Your customer support is very impressive. Not only do you provide the products but you also set up a forum and contribute on a regular basis. I have to comment on your sales staff as well. I have had excellent experiences with my purchases. They are very patient and really make an effort to accommodate orders. O.K., enough brown-nosing. I have decided to hold off on the Grobet ProCraft and get the SPC-9250. I might as well get the right one the first time out, it makes more sense in the long run. I also plan and maybe doing some small anodizing in the future and from what I understand the SPC-9250 is recommended for this as well. And with the timing of that great 7 day sale going on right now, I will probably pull the trigger sometime this week. Thank you also for your reply too Jerry. I am always greatfil when someone shares their knowledge and/or experience however, I'm gonna go with the SPC-9250 Cadillac.