These were sent to me by a CR list member, as an experiment. For $10 (shipped), I promised to refinish them for him. The idea was NOT to make some sort of profit, but to improve my skill set. First step is to soak the nuts overnight in Evapo-Rust to remove as much surface rust as possible.
Here I am de-plating the two large nuts after de-rusting them. The idea of using a Weinmann 500 brake caliper to hold the M6 nuts was not a winning idea.
I have found its almost impossible to polish deeply pitted stuff without a lathe or turning or buffing wheel. Here I am using my drill as a lathe. The nut is mounted on a Weinmann brake-lever clamp bolt, an M6 bolt.
To my surprise, the rust was quite deep. After polishing for a little while with 400 grit sandpaper, i gave up and decided to use a dremel with a flap wheel to remove all of the pitting. I run them both at the same time to produce even sanding.
The next steps were (a) Flap wheel polishing, (b) 400-grit polishing, (c) 1000 grit polishing, (d) 2000 grit polishing, (e) Nevr-Dull polishing. I didn't take pictures of this process (what's to photograph, and I need a 3rd arm to take pictures while doing this??)
Now it's time to for some brush plating.
Brush Plating is the process of plating a piece of steel using a wand dipped in plating solution. As you probably know, most bicycle chrome is actually two layers - bright Nickel (a silver-yellow color), plus chrome (a bluish color to cancel out the yellow.) A single layer of Chrome won't work because it's too porous to protect the steel by itself, and does not adhere well to steel.
My Brush plating set (plug'n'plate) comes from Caswell Plating, they currently cost about $33 = ($12(plating solution), $6(plating wand), $15(power supply.) This is the cheapest plating set on the planet. Since this is a 1-step process, a combination of Nickel and Cobalt (which is sort of bluish) is used to achieve a look that is nearly identical to chrome. I can tell the difference only side-by-side under strong fluorescent lights - only because the brush plated chrome is a tiny bit more "yellow" than the neutral or bluish chrome. I have used this kit to repair several small (1/4") damaged areas of the seat stays of a Raleigh International frameset, and the repair is impossible to detect.
The set comes with a 4.5v adapter, a plating wand (stainless steel), and the nickel-cobalt plating fluid. You hook the positive end of the AC adapter to the plating wand, and the negative end to the item to be plated, dip the wand in the fluid, and brush it across the item several times. Brushing prevents chroming salt deposits from building up too much on the item. You can also swap the +/- AC Adapter leads to de-plate manufacturer chrome. You can also dunk small items and the wand in the fluid - to plate or de-plate - but I have had some trouble with uneven dunk-plating - you must stir the fluid constantly.
I had repeated difficulty centering the bolt in the drill chuck. I finally got smart and decided to do ALL the work with the nut in the drill, even the plating. I will have to repolish the item after plating is complete. The next few pictures show me drawing the plating wand across the nut that is being plated. If the system is working you hear see some fizzing and see bubbles at the edges of the wand
It's not shown here but I did about 5 minutes of plating, then repolished (1000 / 2000 grit), then another 5 minutes of plating, then another round of 2000/nevr dull polishing.
Here are two pictures of the result, outside in the sun, before re-polishing
Same thing - not yet polished - different lighting environment.
Here is the final polished nut next to the 2nd nut of the same type, not yet refinished.
Oops!! I accidentally missed polishing out some "scoring" ... c'est la vie !!
For nuts #2, #3, #4, i got smart and made up an array of sandpapers on a file, with some paper towel for padding behind the sandpapers. This way, i could file the nuts quickly on the drill, without concern for burning my fingers. When I say quickly, I mean in 10 minutes per nut - not 60 minutes.
Here's one of the tiny M4 nuts in the drill chuck, a before and-after picture
WHEW! I'm finished, finally. Total time = 3.5 hrs including a mistake that required a polishing do-over. Now its time to wax the nuts just in case there are any pinhole areas of them that might rust.
END.
Most chrome shops don't have the patience or equipment to do small items successfully. I am trying to develop the patience and equipment in my shop. I tried running some small items through my local chromer. Their solution was to "over-soak" the items in muriatic acid, melting the M4 nuts and rounding-off the M6 nuts substantially. With this work, I am trying to minimize loss of metal to the original nuts, while still getting a nice luminous shine.
Note that it would probably be possible to make another one of these nuts in a drill, with some files or a grinding wheel. The main difficulty would be in finding some M4 or M6 domed threaded stock (or a "tall domed nut") as a departure point, plus it would take perhaps 2 hrs per nut to file down a large nut, maybe 40 minutes for a small one. It would be much easier to copy these nuts in aluminum - when brightly polished, it is hard to tell the difference between aluminum and chromed steel.
Don Gillies
San Diego, CA