This will be a test of my patience....Zinc Plating

[Done-it-again]

I just sorta guessed. Saw a youtube video of a guy doing a caliper similar in size to the "big" ones I do...Porsche 911 front, lets say...and he ran 5 amps for 20 minutes.
The one in my pictures is a 356 rear, same basically as an early 911/912 rear.....a bit smaller, so I ran those at 4 amps for 14 minutes, and run the big ones at 5 amps for 14 minutes. Seems to work well, so I'll keep with that theory. I did some M10x 60mm bolts the other day, 4 on a string at 1.2A for 14 minutes and they turned out great....and didn't break lol. The range of parts I deal with is such that I can sort of establish size catagories and just use trial and error to figure out what works...then write it down and do it like that all the time.

For the $0.60/lb I used to pay for zinc, I can make a pretty fair assumption that nobody gave 2 fucks about the surface area and just turned the knob on the rectifier until they thought it was close, and it was...generally.

So how is the outside test going? any fading? I wonder if this system has the same strength as commercial plating does

We blue zinc a lot of parts, but its all barrel plating, but our treads for our stair stringers are rack plated as they 5' wide x 12"

 

[lbhsbz]

So how is the outside test going? any fading? I wonder if this system has the same strength as commercial plating does

We blue zinc a lot of parts, but its all barrel plating, but our treads for our stair stringers are rack plated as they 5' wide x 12"

Top has been outside for 3 days, bottom has been in a bag inside for 3 days.

I’d say it’s doing great.

I see no reason why this would be any different than the commercial stuff....zinc is zinc. It's all about the chromate. I've checked out the company that my last plating shop buys their chemicals from and they have like 10 different types of trivalent yellow chromate for different purposes. Caswell claims 200hrs of salt spray resistance, while I believe the industry standard accepted is 96 hours.

Caswell's blue chromate (silver) claims 130hrs to white rust corrosion and 170-200hrs to red rust corrosion, which is pretty damn good IMO...seeing as how I've had zinc plated bolts from home depot turn to complete red rust after exposure to river water for less than a few hours

You'd need a big bath to do your stair treads I think. dunno. Maybe a 6" piece of a PVC pipe 6 feet long would work. How is the zinc holding up on a wear surface? I would suspect not that good. I'd probably consider just hot dipping the treads.

Edit:...they look lighter in the picture than they do in person...probably the black desk background. They look the same though with respect to color.

 

[lbhsbz]

Set of 84-89 911 rears….i like the finish. Next batch I'm gonna try 45 seconds in the chromate instead of 30 that I've been doing....maybe get a bit more color. We'll see.

 

[Backlash]

Those calipers look BEAUTIFUL!!

I hope I'm still signed up for your advanced chemistry class. Just getting some hardware together, letting it soak for a few days followed with some Simple Green and scrubbing. I've still got more work to do, but I'm getting there.

 

[lbhsbz]

Guy sent me some calipers for a '60s Jag that should have drum brakes....wanted them to "disappear behind the wheels".

I tried my matte finish zinc w/ black chromate.... Took 4 tries on the first one before I got the method down, but came out tits.

 

[TimeBandit]

Fun fact, I was doing my homework as to why Continental wants new cylinder hold down nuts installed anytime the cylinder is removed for inspection or service.

Having the hardware replated and "baked" is also accepted practice.

The explanation is the Cad plating acts as a lubricant. Ensuring the correct torque is applied to the fastener and not consumed by friction of the fastener if it is reused.

So the plating process on fasteners is not done just for cosmetic reasons.

 

[lbhsbz]

Fun fact, I was doing my homework as to why Continental wants new cylinder hold down nuts installed anytime the cylinder is removed for inspection or service.

Having the hardware replated and "baked" is also accepted practice.

The explanation is the Cad plating acts as a lubricant. Ensuring the correct torque is applied to the fastener and not consumed by friction of the fastener if it is reused.

So the plating process on fasteners is not done just for cosmetic reasons.

Correct. The baking is to alleviate any hydrogen embrittlement.

I've wrote and taught classes on fasteners and how to tighten them properly. One notable example that a few here probably recognize is the front spindle nut on the 2005-2008 F150 2WD.....says right on the nut: "DO NOT REUSE" There is no possible way for this massive nut to fail, but a new one has an adhesive patch as well as a fairly substantial nylon locking feature. The torque spec is 295lb.ft. After it's been used once, these 2 locking features are degraded, and the 295lb.ft will result in a significantly increase clamp on the wheel bearing, which will cause premature failure. This is not a situation where the spindle will or can stretch, as is the case with most fasteners, which is why they rely on the locking features of the nut to hold it down while they rely on the torque value only to create the appropriate clamp force to hold the bearing together.

I don’t torque any bolt/stud type fasteners unless they’re new and the thread conditions on both sides meet the appropriate requirements and a OEM torque value exists.

I’ve done lots of testing to determine the desired stretch of a given fastener size / thread pitch, and just do a bit of math with the thread pitch to determine how much it needs to turn to get there. The trend over the last 15 years or so with automotive OEMs is to call out a torque angle after having snugged up the fastener to eliminate clearance.. (20lb.ft +90° + 90°, for example). If you have an M10x1 bolt and turn it 180° (90+90), it'll stretch 0.5mm regardless of thread condition, rust, how much force it takes to get it there, etc....and result in the appropriate clamp to secure the joint.

As for hydrogen embrittlement...

With what I’m doing, it hasn’t shown itself to be an issue, but typically I don’t plate the fasteners, I give them a zinc phosphate hot bath or a cold blackening process, or they get replaced. This pair got the bolts plated because it was what the customer asked for….they held torque (angle, not value) so I believe they’re good.

I've had my plating shop do lots of hardware in the past....usually Cad black, because I was told that hydrogen embrittlement isn't typically an issue with Cad, only zinc....who knows, I've never had a failure. What I have seen though is yellow residue on the black plating....almost like that bee shit that ends up all over your car.

I played with time in the black chromate and when it left a piece for more than 35 seconds, it turned a shit yellow color after drying....I strip / replate / dump in the chromate again and pull it out at the 30 second mark and dry it, a nice rich black color with no yellowing.

I'm learning that plating is wizardry as much as it is science.....and I'm taking a whole lot of notes.

 

[lbhsbz]

I've got a batch of about 30 calipers that came in a few weeks ago for a customer and I'm not gonna spend 4 days plating each piece one at a time, so they're going up to the shop next week.....Ima get the kid outta bed early before school to join me and have him look over the barrel plate setup they have. He's doing a bunch of Fusion360 design in school, and I got him and momma pretty badass 3D printer (we also have a 20W cnc laser) so hopefully he can make me a little mini barrel plater deal that fits in my plating bucket, and then make a bunch more to sell.....I'll put together a section on my website for stuff like this, if I can get him to stick with it. There's lots of useful stuff that nobody thinks of but everyone needs.

 

[lbhsbz]

Well, It's all kinda gone to shit now....lol, no idea why.

Did 2 pieces on Sunday and they came out great, every piece after that seems to plate about 1/2 the workpiece with no real pattern to it.

Need to check PH and become a chemist this week to figure out WTF happened.

 

[HNL2LHC]

Well, It's all kinda gone to shit now....lol, no idea why.

Did 2 pieces on Sunday and they came out great, every piece after that seems to plate about 1/2 the workpiece with no real pattern to it.

Need to check PH and become a chemist this week to figure out WTF happened.

Interesting. Be sure to post up what issue you find. What kind of $$$ you talking to just start out fresh with the chemicals?

 

[kat_williams]

Well, It's all kinda gone to shit now....lol, no idea why.

Did 2 pieces on Sunday and they came out great, every piece after that seems to plate about 1/2 the workpiece with no real pattern to it.

Need to check PH and become a chemist this week to figure out WTF happened.

Check your chemicals for continuation and check the leads on your wires. Mine would corrode and I would need to replace them. I think I switched to Ti welding rod as wires so they would last longer. But I was anodizing so different chemicals. My other big issue in the beginning was getting parts perfectly clean. I would wear gloves as even oils from my fingers would mess up the finish.

 

[lbhsbz]

Interesting. Be sure to post up what issue you find. What kind of $$$ you talking to just start out fresh with the chemicals?

The Caswell electrolyte ends up being about $40/gallon IIRC. I'm running a 3 gallon tank. Not the end of the world if it's all fucked and I need to start over....I have enough extra on hand to make 6 more gallons (I like to be prepared)...I'll probably start a new tank anyway, then play with the old one in my spare time to see if I can get it working again.

I made my own electrolyte a while back using vinegar and epsom salts.....I think it sort of worked, but I didn't know shit about it at the time so never really pursued it.

I may try a another bucket of that and see how it does, it's like $20 to make 3 gallons, so nothing really to lose.

 

[lbhsbz]

Check your chemicals for continuation and check the leads on your wires. Mine would corrode and I would need to replace them. I think I switched to Ti welding rod as wires so they would last longer. But I was anodizing so different chemicals. My other big issue in the beginning was getting parts perfectly clean. I would wear gloves as even oils from my fingers would mess up the finish.

I changed all my leads because the clips were starting to get nasty....so connections were good. You are 100% correct on the gloves. There is no wiggle room here with skin oils, they destroy the job.

I'm pulling the parts straight out of my shot blaster after a 45 minute cycle and going into the plating....they really can't get any cleaner than that. I even tried an acid dip and then back into the blaster for another 20 minutes to get rid of any residual plating that might be on the part, but that didn't seem to make any difference.

We'll see....next slow day I have

 

[lbhsbz]

HAHA...test strips just showed up, so I dipped one, and compared to the chart on the box. Levels 4-6 look about the same color orange, so I'm somewhere in there lol....go check the book, 5.5-5.8 is ideal. Well, that was a helpful test.

Ordered an electronic PH meter, should be here this afternoon and we'll see at what level of confusion we arrive after that.

 

[mash on it]

Are you using any brightner system? I only know about copper and nickel plating tho.
Organic contamination?
Do you run a hull cell panel?

Dan'l

 

[lbhsbz]

Are you using any brightner system? I only know about copper and nickel plating tho.
Organic contamination?
Do you run a hull cell panel?

Dan'l

No idea what a hull cell panel is.

No, I was not using any brightener....although I do have a bottle of it. Reading through the book that came it, "add more brightener" seems to be the solution to at least half the problems in the "troubleshooting" section, so I added a bit, made no difference.

There are a few dead bugs floating in the tank lol....so maybe organic contamination

 

[mash on it]

Typically organic contamination results in a burning on the finish.
Brighter is consumed during the plating process and added at specific intervals, depending on asf and total amp hours.
Like noted above, could be electrical issues or even agitation issues. Any air or mechanical agitation? Tank filtration? Chlorides from typical tap water can be an issue too. Plating shops I worked for had DI and RO water for different applications/operations.

Dan'l

 

[kat_williams]

I used a fish air pump for agitation. It worked well enough on my 7 gallon tanks. I am sure as you scale up it gets more complicated.

 

[lbhsbz]

I'm using a fish tank pump for agitation....seems to work OK. I bought a 10 pack on Amazon for when I forget to unplug it and it burns up running on the table (I'm on pump 3 lol).

I'm using distilled water for everything. I was buying it at the store, but my buddy has a water distiller thing at his warehouse for forklift batteries, had 200+ gallons in the storage tank at any given time, so I bought a couple 7 gallon water totes to fill up there. Distilled water shouldn't cost 1/2 the price of gas.
No real burning, just screwy plating....not sure how to describe it, see the picture. The darker grey is what I expect to see coming out of the plating tank....then the pickle brightens that up. The lighter color in the pictures.....No idea what's happening there but there isn't any plating on the surface there. I'm running 4 anodes all 90° off each other in the bucket, and I still rotate the part at the 1/2 way mark (7 minutes)....so there's no excuse for "shadowing" causing this. Or cleaning. This piece ran in the blaster for about an hour and was only touched by rubber gloves, that I pulled outta the glove box using rubber gloves. It can't get any cleaner.

 

[mash on it]

Shadowing or a lean solution is my best guess

Dan'l

 

[lbhsbz]

Shadowing or a lean solution is my best guess

Dan'l

It isn't shadowing....clean line of sight to at least 2 anodes at any given point.

The solution is dickered I'm pretty sure. Now....how to fix it. I'm working on that