Hence forth, all new platers posting to this thread must start out with the following sentence.
Hi, my name is XXXXXXX.... and I have a problem.
Welcome Davo. I told you that you would not be disappointed.
Zoom, not sure if you asked this here or in another thread. You wanted to zinc plate your nickle plated spokes. I thought you'd be able to do that, but no so. The nickel will not plate to brass. I know because I tried today. Well, it plated just fine. But when I hit it with the brass brush it flaked off like latex paint on a Teflon pan. Guess the chemistry is not there for zinc on brass to work. I ended up nickel plating it with an ancient plating kit I bought back when you could still send KCn in the mail. Ahhh, the good old days. So don't waste your time trying to plate your nipples.
regards,
Rob
For the home plating specialistWarning - Hydrogen embrittlementI feel I should mention something here that I recently learned while doing some more research on the topic of plating. It involves both the stripping process as well as the plating process.
Hardened steels are prone to hydrogen embrittlement when exposed to H2 under the right conditions. Stripping a hight strength steel in Phos Acid is one of those "right conditions". So apparently is plating in our vinegar bath. This is not an issue with low strength steels. So brackets, nuts, bolts, etc, made from low strength steel are of no concern. But things like spokes are. So, in this thread and in one other, I believe, we spoke about replating spokes. Based on what I've read on the subject, I would not recommend that. There is a process for removing the H2 that bleeds into the base metal and involves baking. But I have not found any info on the process, yet. I've only found that certain milspecs or similar require baking after plating. The gas bubbles given off in the plating process are also H2 so it would appear that the plating process is also able to provide the H2 to high strength steels to cause embrittlement. I was about to strip and replate my spokes and have decided to just clean them up and maybe put some silver paint here and there on bare spots. Others here, Wilf I believe is one, have replated spokes. It could be that our spokes are not of the grade of steel that comes into the range for risk here. From what I've read, anything over Rockwell C 40 is a steel that is a risk for this. regards, Rob Snakeoil,
I did try plating a spoke once but it didn't "take" so I abandoned that idea. Hydrogen embrittlement is something to be aware of. I read somewhere that the effects can be mitigated by baking (250 F for 2 to 4 hours?). I don't think the parts I plate(d) would be at risk. Hydrogen gas bubbles are released at the cathode and oxygen bubbles are released at the zinc anode. Wilf Jensen, I took a quick look at Geomet. It appears this coating is similar to the coatings we put on axial compressor blades for severe environments. Sermatel in the US also offers coatings like these. Basically, it is backed on paint and very durable. To survive in a gas turbine compressor environment, it needs to be tough. I don't think these coatings lend themselves to the home hobbyist, but I could be wrong there. Once might have said that about powder coating when it first came out, too. I did not spend any time looking for details on the coatings. But given that is is intended to replace cad coating, I would think that coating thicknesses lend themselves to fitted and threaded parts. I think most of the bolting on our bikes is grade 5 stuff. Could be some grade 8 fasteners for things like sprocket bolts, triple tree clamping bolts and the like. regards, Rob I had a long conversation with Robert Buchanan at Buchanans Spoke and Rim today. Nice guy and very candid. I'm considering making the plunge for shouldered aluminum rims and stainless spokes. While I had him on the phone I asked a few other questions that some of you might be interested in.
I asked about stainless nipples and the possibility of galling on stainless spokes. He said that over the years they have modified their thread design and clearances as well as gone to a wire drawing oil that then include with every set of spokes that has eliminated any galling issues. He went on to say that they get quite a few rims they have laced in the past with ss spokes and nipples for either a rim change or tune up and they have yet to run into a nippled that was seized on the spoke. That was one of my major concerns regarding ss nipples and spokes. I then asked him about H2 embrittlement and how they deal with it. He was very candid on this topic. He said they send their spokes out for plating, which is chrome in their case. Their plater has an oven and is supposed to be backing the spokes (he said 2 hours at 400) to remove any entrained H2 from the plating process. He said they do not watch over him so they also bake all their spokes in their oven to be sure. But he also admitted that the de-embrittlement process calls for the baking to immediately follow the embrittlement process, be it acid etching or plating. So he said he's not sure their baking adds any value. So I asked the next obvious question. Over the years have the run into any problems with spokes failing due to H2 embrittlement? He said years ago, they used to actually offer replating service for customers spokes. That is where they saw problems with H2 embrittlement. He told me a story about a customer that had them rechrome a set of their old spokes that he had used for some time. He came back all upset because a spoke or two had broken while he was riding. Robert said he was explaining the risks of H2 embrittlement and the guy was not buying it. Then, with the wheel sitting on the counter, one of the spokes failed and the nipple shot across the room. The guy quit complaining and asked if they would lace up the wheel with a new set of chrome spokes. My take away from this conversation is the stripping process, which involves acid, is probably the real culprit in H2 embrittlement of spokes, versus the plating process itself. Other sites I've seen regarding queries on how to strip cad from parts said mechanical removal processes such as blasting or sanding are the best methods for high strength steel. Of course it was qualified with a follow up comment that airborne cadmium can be deadly so a full blown air containment system needs to be in place. Needless to say, we are not going to have one of those in our garages. Kinda defeats the point of plating at home. So, the moral of the story is don't strip and replate your grade 8 bolts and nuts. If you do, then have a plan to pop them in the oven at 400 F for at least 2 hours. And I cannot say if 2 hours is right, because that is for spokes and nuts and bolts can be larger and take longer. Another point is if you are going to respoke your wheels, it looks like it is cheaper to go with ss spokes and nipples than to go with stock spokes and nipples. So unless you are doing a 100 point restoration, I'd go with stainless and you can forget about them for the rest of your life. regards, Rob
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