1986 560SL with M120 V12 Engine, 1988 560SL Stock
Every time I put a dirty part back on my car, I think of you with envy. Nice job.
Thanks for your kind words... but more often then not the parts cleaning obsession is my cross to bear. It's like painting a bridge, by the time you're done, it's time to go back and start at the other end again.Every time I put a dirty part back on my car, I think of you with envy. Nice job.
I would thing for sheet metal parts, You could weigh the part, then with the known thickness you could back out the plate area and add a good estimate for the edges. Steel weighs 0.284Lb/in^3. So divide part weight by 0.284 to get the volume in cubic inches. Now divide the volume by the sheet metal thickness to get the area. Multiply the area by 2 because there are two sides. Add an additional area to compensate for the edges.This plating is driving me crazy. According to everything I've read, including the Caswell Plating Manual Version X, the correct plating current is .14 amps per sq. inch of plating surface. Flat plates are easy to figure and Caswell gives you a formula to use for bolts but multi-curved and bent brackets are near impossible to calculate. So to make an educated guess I imagine the oddly shaped bracket as it would appear if it were a flat plate and then subtract those areas where there is not metal.
Take the bracket below as an example. It's 4" long and 2" wide at it's widest point (measuring around the bend). If you flatten that out it's 4x2 or 8 sq inches. Clearly at least half of those 8 sq inches don't actually exist in the piece, not to mention all the large holes. So we can assume that the actual part is only comprised of a 4 sq inch surface. Inasmuch as we will be plating both sides we double that 4 sq inch calculation to 8 sq inches which is a very generous over estimation of the actual sq inches of surface to be plated. Using the formula for calculating the required current for plating which is .14 amps per square inch (or 140 milliamps per square inch) we arrive at an optimal plating current of 8 x .14 = 1.12 amps.
The standard time for plating Zinc is 20 minutes per .001" plating thickness. Believe it or not .001" plating thickness is plenty but if you require additional thickness for maximum protection in harsh environments you can plate for longer periods, there is however a point beyond which there is no additional benefit and in fact there are times when too much thickness can be detrimental on things like nuts and bolts.
So for the bracket below, I set the current at 1.1 amps and the time to 20 minutes. After the 20 minutes I checked the part and found there was no plating deposited on the part. I then set the current at 1.5 amps and 20 minutes later the result was the same... no plating. I turned up the current to 2 amps... no joy... 2.5 amps... no joy. Finally at 3 amps the zinc began to deposit on the part and after 20 minutes the part was fully plated. Three amps is almost 3 times the calculated current needed to plate the part... and even the 1.12 was a gross overestimation.
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So next I tried to plate one of the smaller and much thinner brackets and this time it was a relatively flat part so calculating the sq inch surface was a breeze. The part was basically 2' x 2" so 4 sq in x 2 (both sides) 8 sq inches. The very same 8 sq. inches of surface area I just finished plating the last part at 3 amps, so I left it set at 3 amps. Here is the result. The plating is burned and pitted with bubbles indicating way too much current was used during the plating process.
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I finally had to adopt my own method for determining the correct current flow. When I place the part in the plating tank I start out with very low current and slowly increase it until I see a mild frothing taking place on the surface of the part. It's like little tiny bubbles eminating from the surface of the part being plated which appears to indicate that the zinc is migrating from the anodes to the part. I think it has something to do with hydrogen but I'm not sure. In any event, once I see the bubbles forming I leave the current at that setting until the tiny bubbles either stop forming or the plating is done. You can tell if the plating is done by lifting the part out of the plating solution and if you don't see a nice bright zinc coating than put it back in the solution and increase the current until you see the tiny bubbles again. You can lift the part out of the plating solution as often as you like and once you can see the bright zinc coating, you can stop the plating and move on to the Chromate tank.
More pictures later... now back to work.
Looking real good. But now you have to paint the car before you put it in.Plating came to a screeching halt when my regulated DC power supply bit the dust. Ordered a new one... it arrives Monday.
Here's what I've got so far...
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I may just finish this thing in time for some Fall top down driving. 🤞
Not yet... I need to drive it for a while before I paint it, but make no mistake, I will paint it... Silver Blue of course.Looking real good. But now you have to paint the car before you put it in.
Do stop by when your in NCNot yet... I need to drive it for a while before I paint it, but make no mistake, I will paint it... Silver Blue of course.
Once it's running and I've changed the oil a few times and if the reports all come back good, I'm planning on driving her down south to visit a few of my sisters... one is in North Carolina (Charlotte) and two are in Georgia. I have another sister in Arizona but that trip will have to wait.
Yup... unfortunately my DC power supply didn't (nothing to do with the rubber).It looks like the rubber survived the planting process no problem.
I have way too many of those piles.The box full of labeled zip lock bags containing parts and hardware for reassembly is getting smaller but I still find myself on long searches for things that never made it into bags. On one of my searches I came across this not so gentle reminder to not throw parts at a problem but instead look for the cause.
Here's a pile of money I probably didn't need to spend:
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Thank you.You sure aren't slacking on the details. The dremel-ing, and plating look great. It's not only going to run like a new engine, but look like one too when you're finished.
Did you buy longer anodes? How did you position them in a rectangular tank? I was thinking I'd buy rectangular tanks too and maybe connect multiple anodes together that run the entire length on both the long sides of the rectangular plating tank so the fuel line will get even plating over it's entire length.Looks great, my plan is to plate the longest line in two halves I previously bought rectangular tanks that fit all but one.