DIY Chrome Prep. Save a bunch of money (pics)

[David Luciani]

rescued article by Sam Bennet

Forget what you know or don't know about chrome plating. Indulge me in this write-up.

Unless you're in the business, hexavalent vs. trivalent, or strike copper vs. cyanide copper is someone else's problem. All you need to know is plating is prep.

We all know prep labor = $ and the less prep time, the less you pay. This DIY will show you how to save money. I'm going to show good practice and some common errors. When you know what fickle inspectors look for, you can eliminate these errors yourself.

I've been fascinated with metal finishing since my Dad took
me on a tour of Modesto Chrome plating in 85. I was 9. Everything was covered in black dust. Men walking around like they worked in the coal mines. I saw piles of junk in the office and mirror finished parts coming out the other end. It was magic!

The next year I was at the Concours de'Elgance and to this day I remember my Dad {pointing at a driver side mirror} saying, "See the grind marks in your reflection, that's lousy chrome".
30 years later I find myself in the cross-hairs of the consummate perfectionist.

I hope I can keep this DIY running for a bit as things come up. Just recently I received my last order and I'm done with plating until the next project. In the meantime, I figured I could make something and illustrate the basics.
Show Chrome.



I needed to make a throttle cable adapter for the boy's kart. It's .125 mild steel plate.



Rules of prep:
1) You'll be shocked how much time is spent using sanding abrasives.
Pits, scratches, waves, or any imperfections need to be eliminated while sanding. You may need something as course as 120 to remove enough material to get below a small pit. Sure, you could filler weld, or use a build copper plating method, but many pits can be eliminated without having to go to extremes.
From 120, you need to remove all of those scratches with 240, then 320, 400, etc.




2) Each time you move to the next finer grit, you need to rotate your grinding pattern 90*.
Grinding perpendicular to your last abrasive will level the peaks and valleys you created with the more course media.
Move the piece around in artificial light to illuminate scratches.
Don't move to the next step without removing all of the blemishes. Note here: I'm seeing some slight radius'ing of the holes. This is a common error and can be avoided. I could easily plug the holes with the correct bolts and minimize distortion. I could shove a 1.5" tube in the large opening and sacrifice it for a flatter finish.






3)When you're happy with the sanding, find a buffer. You'll need at least 3/4hp and 3600 rpm. At this size you should have no problem with a 10" wheel and high linear velocity. This process both "cuts" and "polishes" parts.
The first wheel you'll use is called Sisal. It's just rope stitched together. It holds compound well, is hard, and cuts fast.
The best compound to start with is usually a black colored, greasy, and mildly abrasive brick. Sometimes it's called "stainless", or "emery". By itself this compound generates a nice reflective finish. More importantly it will show you where you missed with sanding.

4) Bad things happen with a buffer.
The health and safety hazards are obvious.
Material is removed and edges are smoothed very quickly in this step.
Pits "grow tails"
Bolt holes are elongated.
Too much pressure creates grind marks.

You will need pressure, but experience will quickly tell you how much. Pits only grow tails because you couldn't/didn't remove pits. Bolt hole elongation can mostly be prevented by putting bolts or tubes in the holes for sacrifice.
If you generate grind marks, you need to go back a step and remove them sanding.




5) When you're done with sisal you can use a sewn denim or sewn cotton wheel with the same compound. This wheel is stiff and has no rope. This will really show you if you missed anything with prior steps. If you have, then start with 320, then sisal, and denim.



Here you should see minimal waviness and can read a business card backward with no problem.

AT THIS POINT YOUR PLATER STOPS PREP AND GOES TO THE TANK!

No, you don't need a "color buff" to go in the tank. It makes no difference in the outcome. I used to "color buff" all my parts and the plater would say, "why did you do this?". They had even confused my color buff parts for already chrome plated parts!

Truth is.. Color Buff (which is using a white compound with a soft cotton wheel) helps the polisher find the remaining errors. This way he/she can go back and fix it with prior steps.




I've spent 3X the time writing this than I spent in the garage prepping this part. I missed a few pits and I'll start over again trying to get it perfect.

A plater would charge $40+ to chrome this part from the first picture. He has to hire some guy to do all of the steps in between.

YOU NEED TO FIND A PLATER WHO WILL 'PLATE ONLY'. In the world of plating this means you accept the prep work and you are using your plater for his tanks only. You accept the responsibility of peeling, pitting, blemishes, etc.

If you bring parts to your plater with 'plate only' instructions he should understand he is going to"
1) caustic dip and rinse
2) copper plate and rinse
3) nickel plate and rinse
4) chrome plate for maybe 1 minute and rinse.

The process takes less than an hour for most parts and they should be happy to 'plate only'.
The part I illustrated above would cost me less than $5 if it was with other smalls.

Those R1 parts pictured.... I'm not going to tell you, but it was less than what it costs to fill up my truck. With that said, I've got thousands of hours behind a buffer, and over 1K in consumables.

If you're like me and have a lot of highly customized restorations/modifications, then take this route. There is nothing like being black from head to toe, throwing away shoes every few months, the coughing, black boogers, and of course your wife complaining about the shower.

Worth more than all of that is the satisfaction of knowing you take can credit for all of your work. Your labor made that steering shaft perfect, your labor allowed me to see my reflection in your steering arm, those flawless tanks on a Hornet Enduro.

Get out there and make it happen!


These parts are before chrome!





Some polished aluminum I did for my karts.




Save
Save
Save