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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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Every time I put a dirty part back on my car, I think of you with envy. Nice job.
 

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1983 380 SL
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3,344 Posts
Discussion Starter #822
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.

My tanks aren't big, but today I'm going to try plating multiple brackets at the same time. This should be a disaster... pictures to follow of my success (or failure).
 

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1983 380 SL
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3,344 Posts
Discussion Starter #823
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.
MercZincChromate3.jpg


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.
MercPlatingGoneWrong.jpg

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.
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
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10,807 Posts
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.
View attachment 2651622


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.
View attachment 2651638

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.
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.
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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10,807 Posts

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Premium Member
1983 380 SL
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3,344 Posts
Discussion Starter #827
Looking real good. But now you have to paint the car before you put it in. :ROFLMAO: :ROFLMAO: :ROFLMAO:
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.
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.
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
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10,807 Posts
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.
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.
Do stop by when your in NC
 

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Premium Member
1983 380 SL
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3,344 Posts
Discussion Starter #829
Do stop by when your in NC
I will, but first I need to get this engine installed and running, and I'm not even sure it will be a viable ride with a steel sleeve in #6.
 

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1983 380 SL
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3,344 Posts
Discussion Starter #830
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: :(

MercPileOfMoneyWasted.jpg
 

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Premium Member
1983 380 SL
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3,344 Posts
Discussion Starter #832
It looks like the rubber survived the planting process no problem.
Yup... unfortunately my DC power supply didn't (nothing to do with the rubber).
My old supply had a capacity of 30V and 5 amps. While plating a larger part I pushed the DC supply to it's max and it couldn't handle it. Pfffffft went the supply.
The new supply has a 30 volt 10 amp capacity and it arrives tomorrow.
Back to work
 

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Registered
1987 560 SL, 1990 300E 4Matic
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644 Posts
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.
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
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10,807 Posts
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: :(

View attachment 2651816
I have way too many of those piles.
 

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Premium Member
1983 380 SL
Joined
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3,344 Posts
Discussion Starter #835
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.
Thank you.
psst... I know where all the dirt is that I didn't get out and don't think for a second it doesn't haunt me at night. :eek:
 

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Premium Member
1983 380 SL
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3,344 Posts
Discussion Starter #837
I've always known that my job wouldn't be complete unless I re-plated the fuel lines from the FD to the injectors but I wasn't certain I could do it satisfactorily, partially because of my tank size limitations and partially because the lines were pitted and ugly. Here's my first attempt.

MercNbr4FuelLine.jpg

To say I was pleased would be an understatement. I plugged both ends of the fuel line with high temp plugs I use for powder coating and then bead blasted the crud off the line and connectors. I then used very fine steal wool to bring the lines to a shine, submerged them in a caustic soda bath at 170 f and into the plating tank for 15 minuets at 1.2 amps, turn and then another 15 minutes and finally rinse and then 15 seconds in the chromate tank. Only 7 more to go but I'll run into a tank size problem. Some of the fuel lines are just too long to fit in my tank so I'll need to get a tank or two that is long and narrow instead of round and 8" deep. No doubt it will be a PITA, but if the result is half as good as the first attempt I'll be very happy.
 

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1979 450SL UK spec
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1,661 Posts
Looks great with a nice shine! My plan is to plate the longest line in two halves I previously bought rectangular tanks that fit all but one.

Were your plugs push on or screw on? I wonder if there is any real danger of not using plugs?

2652263
 

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w108 & w107
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184 Posts
Admire your efforts.
I think i questioned your plating set-up about 6 months ago or more, and I've been hooked ever since and enjoy following your progress.
I noticed pierre hedary did a video this week regarding hardware colours. It's really a personal choice, and your results look great
 

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Premium Member
1983 380 SL
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3,344 Posts
Discussion Starter #840 (Edited)
Looks great, my plan is to plate the longest line in two halves I previously bought rectangular tanks that fit all but one.
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.

How did you handle the connectors on the end? In my first attempt I plugged them (see photo) but the connectors didn't make good electrical contact with the fuel line itself and as a result they didn't plate well. The reason I plugged the ends was to keep all the fluids involved from penetrating the inside of the fuel lines but I'm beginning to think that doesn't matter as long as you blow out the lines with compressed air after plating is complete but before immersion in the chromate tank.

In the photo below the black arrows show the plugs I used. Red arrows show where the plating did not take well.
The problem is that the connectors are not making hard contact with the fuel lines during plating so the magnetic lines of force are not directing plating to the ends.
Also, the plugs are not forming a perfect seal (especially the green plug) and fluid is becoming trapped inside the tube ends which is causing additional chromate degradation as it seeps out during drying.

I'm thinking that what I'll do is abandon the plug the ends method and not try to keep fluids out of the inside of the tubes. In addition, I ordered 18 awg copper wire (I've been using 12 & 14 awg) that I can more easily wrap around the threaded end and the hex end and connect both of the wires from the ends to the wire from the fuel line itself, so all 3 wires connect to the cathode. That way I should get more even distribution of the plating and after the fuel line leaves the plate tank (but before entering the chromate tank), I'll blow out the inside of the tube with compressed air. I may also polish the zinc plating to a high shine with fine steel wool prior to going into the chromate tank.

The chromate goes on very fast, only seconds, and dries very hard but it takes 48 hours to reach full hardness. If you touch the part before the chromate hardens you can rub it off with your thumb so it's important to leave it alone to dry for 2 days before blowing out the fuel lines for the final time. Hopefully there won't be any more contamination inside the fuel lines after I'm done.

MercFuelLineEnds copy.jpg
 
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