Zinc plating DIY kit project

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Zinc plating DIY kit project

Post by Stephenl » Mon Nov 04, 2013 3:17 am

I'm going to start this thread as a how to guide but with a side order of "learn from my mistakes" and "please tell me what to do"! :)

Inspired by the Swoakes lad and his rather nice looking galvanizing output I've decided to make my own kit.

I thought about buying this
http://www.eastwood.com/ew-electroplati ... -zinc.html
but on reflection it is tiny and of limited scope. I at least want the ability to plate things a bit bigger than a exhaust u bolt which seemed to be about all that was capable of.

I found this guide from triumph motorcycles people which i have decided to try and follow.
http://www.triumphrat.net/classic-vinta ... -home.html
Materials
Zinc - I used pure zinc roof strips sold to prevent fungus on roofing
Vinegar
Epsom Salts - 100gm/liter
Sugar - 120 gm/liter
Small 12vdc power supply (3 volts minimum)
plastic pail
digitial multimeter or DMM (for measuring milliamps)
small variable resistor (potentiometer or pot) - 500 ohms Radio Shack
Brass wire brush
Digital timer - not absolutely required, but makes things easier.

Building the System
You make cathodes from the zinc plate and line the walls of the pail with them. Connect them all together using copper wire and the end of that wire becomes the positive terminal for the set up.

String another copper wire across the top of the pail that is electrically isolated from the cathodes. That wire is the negative terminal and the wire from which you will hand the parts to be plated. We'll call this the top wire.

Mix vinegar, Epsom salts and sugar until all is dissolved and fill the pail with the solution. Hang the parts to be plated from the Top wire with either copper or stainless steel wire so the part is fully submerged in the plating bath. DO NOT LET THE PARTS OR THE HANGER WIRE COME IN CONTACT WITH THE CATHODE!! THIS WILL SHORT OUT YOUR CHARGER. The current flows thru the bath, which is an electrolyte and conducts current via the Epsom Salts you added.

Connect the negative lead of the charger to the negative terminal of the set up (Top wire) . Connect the positive lead of the charger to one terminal of the potentiometer. Connect the positive lead of the DMM to the other terminal on the pot. Connect the negative lead of the DMM to the positive terminal of the set up (cathode wire). Set the DMM to milliamps or amps as your meter requires.

Look at the rating on your charger. It should give the output voltage and the output current. It may give the voltage and watts instead. If it gives watts, just divide the watts by the output voltage to get the output current in milliamps. That output current is your max current. If you exceed that, you will damage your charger.

Part Prep
You need to remove all the old plating and any rust prior to plating. You can bead blast, acid clean, wire brush, sand, whatever you prefer. Remember that the plated finish is only as good as the finish on the base metal being plated. I use Phosphoric Acid to remove any old Cad plating and any rust. Stubborn rust like deep pits gets bead blasted. Then with rubber gloves on to prevent greasy finger prints, degrease the part thoroughly in something like acetone, dry it and then suspend it in the bath.

Plating
With everything connected and the part in the bath plug in your charger. Adjust the pot so that the current in ma is at or below the max output current for your charger.

Leave the part in the bath for 10 to 30 minutes. Unplug the charger and remove the part. The part should be plated with a dull light gray coating. Brush the plated surface (this is called carding) with the brass brush until the bright zinc plating appears. You can put the part back in the bath for a second coat, which I normally do.

Keep in mind that the plating will add anywhere from 0.0005 to 0.003 inch of plating, depending on how long you plate it. So fitted parts may need to be masked with paint or tape or sanded down when finished. The axel in the attached photo would not fit thru the wheel bearing when it was done so I polished the plating from the shaft section. The OEM plating was only on the ends of the axel as well.

Attached is a photo of some 305 Scrambler parts I plated over the weekend. This was the first time I've ever done this, having read about the process on the 305 forum on Friday. Here's a link to that thread so you can read the other details I observed as I did this. http://www.honda305.com/forums/viewtopic.php?t=6584

I've also attached a photo of my set up. My pail is a 1/2 gallon pail that had hot tube chemicals in it before. Try your local diner for similar plastic containers. They get tons of them and normally toss them out. Don't use a huge 5 gal pail because proximity of the part to the cathodes determines the time required to get a good plated surface. Also note that the plating is line of sight. By that I mean the zinc ions travel from the cathode to the anode (part) in a straight line. So if you have only one cathode, the surface facing it will plate better than the surface not facing it. This is why I say to surround the outer wall of your pail with zinc cathodes all hooked in series. This also means that for parts like the axel spacers and that big axel nut in the photo, I had to make a small cathode to fit inside the ID of those parts and not touch. I made a smaller set up with a small plastic butter tub to plate the ID on those parts first, and then did the outer surfaces.
I have bought one of these bad boys, which upon arrival was much bigger than I imagined it would be and gave the postie quite a shock when he picked it up.
Image
http://www.amazon.com/Roto-Metals-Zinc- ... zinc+ingot
Actual size with gloves for scaleImage

I have also ordered this 500ohm potentiometer.
Image
On this item I am simply going by the name of it. I'm not sure what it does or if it is the right thing, nor how to wire it up. But that is what the instructions say to buy and that is what I have bought; how can i go wrong? :w It hasn't yet arrived, so once it does I will put some effort into figuring that out.
http://www.amazon.com/Parts-Express-500 ... entiometer

I've got a few battery chargers, big and small, so hoping they will work as the power source.

I'll be out shopping for vinegar and the like early this week so that I can get started.

So please feel free to point out what I am doing wrong :shock: , tell me what to do :wink: or follow the fun :D .


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Re: Zinc plating DIY kit project

Post by Scimher » Mon Nov 04, 2013 4:25 am

Keeping my fingers crossed Stephen.....Fascinated to see the outcome...



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Re: Zinc plating DIY kit project

Post by toomanysabres » Mon Nov 04, 2013 9:02 am

Wiring the pot. Use the middle terminal and one of the others. Just depends on which way you want to turn it to increase the resistance. Make sure its a linear resistance and not a log scale one which is used mainly for audio volume controls. Wire wound ones will be linear. Maplins must have the right one.


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Re: Zinc plating DIY kit project

Post by philhoward » Mon Nov 04, 2013 9:55 am

No Maplin in the US, Geoff! Googling seems to suggest its a linear so should be fine?

Other way to wire it is to join to the centre terminal to one of the others to make one end, and the third terminal to make the other.


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Re: Zinc plating DIY kit project

Post by windy » Mon Nov 04, 2013 10:35 am

The pot shown is only 1/2 watt rated so isn't really man enough for the job. Watts are a product of volts x amps, so at 12 volts you could only draw 0.04 amps through it. Obviously you would probably not want to drop 12v across it, only a portion of it, but you get the idea? Btw some of the wirewound speaker control pots are quite highly rated, or maybe something like this;
http://www.ebay.co.uk/itm/15-Watt-Wirew ... 1c36996274
Also, just having read the thread linked to completely, he goes on to say a pot in the range of 25 to 100 ohms would be more suitable than the 500 ohm.



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Re: Zinc plating DIY kit project

Post by Roger Pennington » Mon Nov 04, 2013 12:18 pm

Electrics aren't my speciality :oops: but when the original quote says
You make cathodes from the zinc plate and line the walls of the pail with them. Connect them all together using copper wire and the end of that wire becomes the positive terminal for the set up.
Hasn't he got that (the naming, not the electrical connection) the wrong way round? Surely the zinc bits connected to +ve are the Anodes and the parts to be plated (connected to the -ve) are the Cathodes?


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Re: Zinc plating DIY kit project

Post by Stephenl » Mon Nov 04, 2013 2:10 pm

Roger, that times a bell I think on the triumph site he corrects himself. You are right.


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Re: Zinc plating DIY kit project

Post by Stephenl » Fri Nov 08, 2013 4:48 am

well my potentiometer arrived looking very much like something else. Now have to wait another week for the right thing to show up. They said I could keep the capacitor which was nice of them, but I have no use for it!
Image
if anyone cares to link me to a web page that enables an idiot (GCSE Physics grade C (after a retake)to understand watts/voltage/ohms and hep me relate it to this project it couldn't do any harm! I read on one of these sites that volts are irrelevant, so maybe an old phone charger could do the job without any need for any resistors?


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Re: Zinc plating DIY kit project

Post by toomanysabres » Fri Nov 08, 2013 10:16 am

I don't know why you wanted a pot in the first place. If you use a 12v battery charger what is wrong with putting a 12v bulb in series with the + output. Then the bulb will 'absorb' the difference between 12 and the conditions established by the electrolyte and the distances between electrodes. The bulb will glow accordingly. Choose a bulb wattage consistent with the max load you can place on the charger. It will protect the charger in case of a direct short while manipulating the bits in the bucket.


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Re: Zinc plating DIY kit project

Post by windy » Fri Nov 08, 2013 11:05 am

The pot is there to adjust the current, as you need a certain amount of current per square cm of area to be plated, ie a bumper needs a lot more current to plate than a few small bolts. Ideally you would use a variable voltage constant current supply. The 500 ohm pot shown a couple of pictures above is totally unsuitable as already mentioned.



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Re: Zinc plating DIY kit project

Post by AJL Electronics » Fri Nov 08, 2013 11:39 am

What we used to use was an electric fire element with a slider added.


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Re: Zinc plating DIY kit project

Post by tony.idle » Fri Nov 08, 2013 12:09 pm

As Geoff suggested a bulb, or switched string of them, offer a substantial degree of current stabilisation. And they're cheap or free. And if they glow red it's a bonus not a disaster.


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Re: Zinc plating DIY kit project

Post by windy » Fri Nov 08, 2013 12:13 pm

1kw (60 ohm) electric fire element, with slider as Andy suggests, in series with a suitable bulb, as Geoff/Tony suggests, could be a good set-up :)



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Re: Zinc plating DIY kit project

Post by toomanysabres » Fri Nov 08, 2013 12:43 pm

My home made battery charger produces 17V so the bulb works as a regulator. If the battery is well down it glows brightly and as the battery rises then it dims down. The benefit of the bulb is because bulbs have steep resistance/temperature characteristic. So as the bulb goes dimmer the resistance drops and thus the charging current is maintained. Its a kind of crude constant current device. You can prove that by measuring the resistance of a 48W 12V bulb. You would expect it to be 3 ohms but cold it is very nearly a short circuit. It only becomes that when at full brightness. ie 12V 3Ω 4A.


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Re: Zinc plating DIY kit project

Post by tony.idle » Fri Nov 08, 2013 3:08 pm

Is there a simple formula that relates those last three figures? :W


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