I thought I'd add a few more comments here based on my recent experience to help the next guy.
The gritty stuff found on the small parts during the last plating session turned out to be piece of the cathode that were shedding from the edge of a couple of the plates. I had used up quite a bit of the zinc cathodes and the edges on two of them were looking a little ragged. I poured my plating bath thru a coffee filter and filtered out all the little bits of zinc.
It turns out the the problem plating into pits and deep holes was really a corrosion problem. The center drilled into the end of the front axel was still rusty. So I did some scraping with a dental pick to loosen up the scale. put a drop of phos acid in it for about an hour or two to eat the rust and then blasted the hole with my bead blaster until it was silver. Then when I replated that end of the axel, I made sure the hole did not have an air bubble trapped in it. I put the end with the center hole up close to a cathode plate and then turned it and tapped it a bit every 5 minutes to release any trapped gas and evenly plate the hole. Worked like a champ. Hole is nicely plated now.
I took a few measurements of diameters to see how thick the plating was. On the 14 ga wire I used for hangers, it was as much as 0.002 to 0.003 inch thick. I was surprised at this, but these hangers went thru several parts cycles, so they were "plated to death" for lack of a better description.
While on the subject of plating thickness, I noticed that the front axel was only plated on the ends. The threaded end and the tapered portion leading up to the main body, and the larger diameter head end (with the hole in it) were plated, but the main shaft portion was not. I plated the hole thing because I could and when I tried to slide a wheel bearing on the axel, it would not go. So I chucked it in the lather and sanded off the plating on the shaft portion where the bearing ride. I measured it before and after and the shaft was 0.001 to 0.002 inch thicker due to plating. If I were to do an axel again, I'd mask the shaft portion with paint or tape to avoid having to sand the plating off later. Those of you who do not have lathes to make this process easy need to consider masking certain parts.
Another thing I noticed is as the bath was used, the stickiness, due to the sugar content seemed to diminish. I suspect that the sugar gets used up in the process. Remember, the sugar is the brightener for the plating and makes the zinc crystals smaller, which means shinier. I need to research this factor, but my guess is if you continue to use the same solution, you might need to add more sugar after some point in time.
The final point is the effect of corrosion. If you miss any corrosion on the steel parts, the zinc with not plate those areas. That means you either need to scrub, scrap, acid soak, bead blast or similar to assure are no small pits, pockets, or nooks and crannies with remaining rust. When I did my exhaust flanges, which are cast iron, I bead blasted them almost to excess. The result was no pits anywhere in the plated surface. Other parts were not blasted just acid soaked and I should have gone after them a little more aggresively. For those parts, I can live with the pits and will just paint them or grease them upon reassembly. But for those exposed and/or visually important, removal of all rust/corrosion is key to a 100% plated surface. The nice thing about zinc is is it less noble than iron so it will corrode rather than the steel part where pits reside. If you were nickle (or chrome) plating, the more noble nickel would survive and the pit would grow under the surface of the nickel plating. This is a common cause for blade failures in Ni-Cad plated compressor blades in gas turbines.
Here is a pic of my completed CL 77 parts. I think they look damn good. I'll be doing more over the long winter which has just started. I'm going to try a test spoke from an old Harley to see how it comes out. I might just end up unlacing my two wheels and stripping and replating all the spokes. That's $240 in new spoke savings based on Honda prices. More if you go stainless from Buchanan's.
One final note/comment. If these long posts are annoying to some, or put a burden on this forum, please tell me. I can touch type (high school typing back in the 60's) and spend much of my day on a computer for work. Plus, I've done lots of technical writing as part of my job so I kinda enjoy it. I know I really enjoy reading how-to's on subjects I'm new to so it avoids all the pitfalls and that is my intent here. I'm not just trying to take up wavelength.
Wilf, thanks again for sharing your recipe for zinc plating. I think it is fair to say that anyone involved in bringing old bikes or cars back to life should be aware of this process and set up to replate old parts. I can't wait until next spring when somebody asks if I both NOS parts for the bike and I can smile and say, "No, they're all original.... why??".
Best regards,
Rob
For the home plating specialistSnakeoil............nice touch! I hope my stuff turns out that nice. I will be starting with my spokes. Picked up an Atlas DC/AC train transformer that should work. Looks like I will try your electro solution.
Did you polish those pieces after they came out? I add some more info to the thread by next week. Very nice work indeed, Rob! I agree 100% with your observations and tips, and I'm sure others will benefit from your detailed posts.
As you noted, the results are no better than the preparation of the part prior to plating. I don't have a bead blaster so I use electrolysis to eliminate corrosion, then a quick scrub under the tap with a wire brush and immediately into the plating bath before any flash rusting can occur. With respect to the voltage and current, I think there is a minimum voltage (1 to 1.5) necessary to start the process. The current describes the rate of zinc transfer and is therefore the key to the quality of the plating. With all this interest in home plating, I'm considering investing in zinc futures... Wilf Zoom,
The only polishing was on the axel and it was not polishing but really sanding to remove the plating to bring the axel back to spec in order to fit the ID of the wheel bearings. I did polish it once the zinc was removed. Otherwise, you just have to card, which is scrubbing with a brass brush or even steel wool to remove what I believe is an oxide layer left behind by the plating process. As you brush the surface, the dullness is removed and the bright zinc remains. And this is NOT MY PROCESS, Zoom. Wilf shared this process in another thread and it was referenced in this thread which is where I found it. Do large parts one at a time. They come out better. Small parts like washers, nuts, bolts, etc., can be done at the same time. But hang them at different levels in the bath so they do not mask each other. Wilf, I appreciate your kind words and comments. I'm headed over to the vintage Triumph forum I participate on to tell them about this process. I'm surprised nobody has ever mentioned this over there. Or maybe they did and it is buried in some ancient thread. Thanks and best regards, Rob Zinc AnodeEastwood sells a 2-pack of replacement Tin-zinc anodes for $19.99. PN 10049A Pure anodes might eliminate some of the other "stuff" that shows up when plating.
Rob,
I'm glad to have been able to share the "process". It's not mine. Someone on another motorcycle forum posted it, asking if anybody had tried it. I happened to have all the ingredients and equipment at home so I tried it right away and played with it. I liked the results, but aside from my experience with it, there is nothing "mine" about it at all. Happy plating! Wilf
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