Back to this dang brake plate with the badly botched chrome job. This has become my White Whale. I am determined to make this thing look good,
using DIY methods, no matter how much time and money it takes, both of which I have already spent a considerable amount of.
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Still slowly working on this project, jumping around from issue to issue. I have a front drum wheel that's missing the brake plate, so I bought the above plate from one of the big eBay bike parter-outers. Seller is in Canada, price was good but shipping was pretty high, it was a whole wheel, I messaged and said I'd pay the full price for just the plate if the shipping was cheap enough. So, I end up paying $133 USD total to my door for just the above brake plate, as shown.
That's an extremely good deal, BUT...
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The black spray paint comes right off, even with modern useless paint stripper. BUT...
This hub has been CHROMED. But, that's not all. The chrome is a mess. It is completely covered with big and small pits. And, it is ROUGH. It looks like it was hit by a sand blaster, but I know it wasn't. Or, it looks like it was covered with another plating, like nickel or something, but I'm pretty sure that's not right either.
Whatever was done to it, it was done with the plate fully assembled. If you look at the full size image above, you can see that the vent cover was in place when whatever was done happened, and the cover protected the chrome under it, which is gorgeous.
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Here's what I'm talking about. The chrome under the cover looks great. Everywhere else is rough and has big and small pits.
So, I want to get rid of the chrome. I Google it. Acid is popular, but the plate is a combo of mostly aluminum with some cast-in steel parts, there's no way to control what's going to dissolve.
The other popular method is sand blasting. I try it. NOTHING. I guess my blasting media isn't hard and sharp enough.
So, last resort, I go to a black emery buff compound on a sisal wheel. Results shown above, where I hit a corner right next to the vents. Deffinite improvement, but the emery is not nearly aggressive enough. It will never get the big pits out, and it will take forever to get all of the tiny pits out.
All I want is to remove the chrome, so I can get to the easily polished aluminum.
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Some more images of test areas with the emery buff compound to give an idea what I'm dealing with. In the last pic, I was able to really bear down on the edge of the plate with the sisal wheel, and I got all the pits out, but the edge has started to round.
I'm open to suggestions. What's really needed, in my opinion, is a silicon carbide buffing compound, but they don't really make exactly what I want. SiC valve lapping compounds are generally too fine for bulk chrome removal and are a bit expensive. I've been looking at coarse SiC 60/90 grit, which isn't too expensive, mix it with axle grease, and use it on a brand-new, dedicated sisal wheel.
I did a test using a medium grit SiC sanding belt on an inconspicuous place on the plate, and it it ate through the chrome like butter. So, SiC will work, I just need it in a form that I can get into the nooks and crannys.
I'll wait for suggestions and comments, and then I'm buying SiC powder.
Lest you have forgotten, the above post will get you up to speed.
This is the current state of the plate. The shiny areas are where I have tried a variety of polishing techniques and materials.
I was able to use my water-cooled silicon carbide belt setup on the flat wedge-shaped vent area.
Here, I have just started to get all the way down to the aluminum in areas, and you can see how still screwed-up and pitted the surface is. Anyways, started with 36 grit, then 60 grit, then 320, followed by black emery cake on a sisal wheel, then Tripoli on a stiff buffing wheel, and finally White Diamond polishing paste on a soft wheel. This area is now finished and looks perfect, which is important because it is one of the most prominent areas on the plate. Unfortunately, no other areas on the plate are suitable for the belt sander.
This little area was a test of my ability to polish in intricate places. It is also finished. Here, I did not get all the way down to the aluminum. Instead, I smoothed and polished the botched chrome using...
... these Dremel wheels along with polishing paste.
One of my experiments involved this stuff, which I bought on Amazon. First, I tried mixing it with grease to make a paste to be used with a sisal buffing wheel, but I wasn't real happy with that application method.
Ended up making my own buffing cakes -- not an original idea, but I think maybe using silicon carbide is. This was fairly cost effective. Very easy to do and I encourage others to try it. Put a tin can directly on the stove, add one stick of paraffin (1/4 lb.), and a half pound of silicon carbide, mix and pour into a simple mold. You can't see it, but in the filled mold in the left hand picture there is a divider, meaning that mold yielded two bars. The 500 grit is fine enough to stay in suspension. The coarser grits will settle, so you want to wait until the stirred mixture just begins congealing before you pour it into the mold.
BTW -- I searched and searched, but no one seems to make silicon carbide cakes. I think there would be a huge demand for them, and that it is a million dollar idea.
QUICK TECH ALERT: Silicon Carbide is abbreviated SiC, which is how I will refer to it herein out. Aside from a couple of exotics, the only abrasive that is harder than SiC is diamond. SiC is also called carborundum.
Black emery -- the familiar black cakes you can buy everywhere -- is NOT SiC. It is mostly alumina oxide. The alumina oxide in black emery is also called corundum, which is really confusing because it sounds so similar to carborundum which it isn't.
Black emery is pretty hard, but SiC is considerably harder.
Having made my SiC cakes, I tested the 500 Grit (finest) on a quadrant of this alternator cover. It cut through the oxidation like butter and I was really excited, thinking I had made a breakthrough discovery.
I set up a side-by-side comparison of SiC versus emery on a couple of badly oxidized valve covers. The end results speak for themselves, and were virtually identical. Polishing times were a little faster with the SiC, but more material was used. More testing will be done.
[In this pic the rod (top) and the vent cover (left) have already been polished with black emery.]
The other brake plate components had the same botched chrome coating. Clearly, the fully assembled brake plate had been somehow sprayed with metal, which I am calling chrome. This is perplexing. You would think that I am wrong and that it is actually some kind of powder coat, except it is hard as hell, is totally bonded on, and is extremely hard to remove. Remember, that in my previous post, I tried sandblasting it and got nowhere.
This is the back of the plate. Definitely, positively, 100% dipped in chrome. I have no idea what they subsequently did, or why, to the other side.
Before and after. The rod and cover were polished with black emery. Took a really, really long time and is still far from perfect.
The lever arms from the previous pictures. This time, I polished them using SiC. Still took a really, really long time, and once again far from perfect, but acceptable. Sadly, no amount of polishing will redeposit metal into the pits.
Different lever arm, without whatever crap was done to my brake plate, which I thought would make a good test piece of the powers of SiC. I intend to coat the pins and the flaking area with beeswax for short term rust prevention. What they really need is replating or 2K clear coat.
That's about it for now. One last pic to show what I am dealing with. I've got a couple of new ideas -- waiting on some things I ordered from China to arrive.
disc work?
