Chroming Parts

Discussion in 'Finishing Techniques' started by Kyle Boatright, Oct 14, 2019.

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  1. Oct 14, 2019 #1

    Kyle Boatright

    Kyle Boatright

    Kyle Boatright

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    The RV-10 has 4 unique hinges for the doors. They are plain 'ol steel and are partially exposed to the elements. I'm tempted to have them chrome plated to avoid the chipping/rust that (I think) would happen due to the relative motion of the hinge halves if I painted the hinges.

    On the other hand, I've read about hydrogen embrittlement, but don't really understand it. What I wouldn't want to do is create a structural problem in the hinges with the plating process - the hinges are part of a fairly weak door attachment system and I don't want any of them to crack/break.

    So, what questions do I ask at a chrome plating shop to make sure they know what they are doing and to avoid hydrogen embrittlement?
     
  2. Oct 14, 2019 #2

    BBerson

    BBerson

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    I took a Cherokee nose wheel strut to a chrome shop. Got a call back and the shop said the steel tube strut cracked while they were rechroming it. He said they sent it for lab testing. I never heard from them again. My customer bought another used strut.

    Small parts can be zinc galvanized with a propane torch. They sell zinc rods at the welding store.
    Heat it up and rub the zinc on.
     
  3. Oct 14, 2019 #3

    TFF

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    The parts are baked as part of the process to prevent the hydrogen embrittlement. At what step I don’t know. A bumper is not baked.
     
  4. Oct 14, 2019 #4

    cheapracer

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    Get them nickel plated, all problems solved, safe, nice and shiny.
     
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  5. Oct 14, 2019 #5

    AdrianS

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    Or zinced, if you don't want shiny.
     
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  6. Oct 14, 2019 #6

    geaton196

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    Is this safe? I was admonished to never weld galvanized parts. Does the zinc rod melt without fumes?
     
  7. Oct 14, 2019 #7

    Turd Ferguson

    Turd Ferguson

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    talk to your plater and see what kind of options they have. Not any real chrome anymore.
     
  8. Oct 14, 2019 #8

    wsimpso1

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    All kinds of partial info on here...

    All electroplating (or acid washing) of steel can diffuse hydrogen into the steel - leave the hydrogen in and you can develop hydrogen embrittlement. Reputable shops will electroplate, immediately rinse and then bake steel with very little time in between processes. Baking drives the hydrogen off. This includes copper, nickle, chrome, triple plating (copper then nickle then chrome that we are accustomed to as shiny "chrome").

    I had a torque converter part that was acid washed to remove some rusty corrosion (our plant let it sit beyond the known protected time) and the springs broke into pieces as it sat on my desk over a couple days. The phenomenon is real.

    If I were concerned about a hinge in an appearance area corroding and liked bright metal, I would go either electroless nickle or hard chrome. There is a whole family of corrosion proof coatings that look good. Find a guy doing them near you and ask questions about how they prevent hydrogen embrittlement, how each product holds up over time and in the weather, etc. If they are any good at all, they will tell you if baking is needed (electroless processes may not need it and they will say so), how long each coating holds up under salt spray, etc.

    There are also spray (airbrush or spray gun) then bake anti-corrosion materials that can be had in MANY colors that are absolute proof against corrosion.

    Billski
     
  9. Oct 14, 2019 #9

    BBerson

    BBerson

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    The fumes from welding galvanized steel is much worse because the zinc gets vaporized into thick white fumes. Don't breath that.
    Zinc coating isn't welding. Just get the part hot enough to melt the zinc, remove the torch and then rub it on. Don't heat the zinc rod with the torch. Sort of like soldering. After zincing it can't be welded safely without grinding away the zinc.
    Do this zincing outside. Only for small parts. I did a 2" sample. No actual real parts.
     
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  10. Oct 14, 2019 #10

    Hot Wings

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    Another vote for the electroless nickle. There was a shop in my town for a while and a friend worked there. Got all kinds of things plated for a VERY reasonable cost. As noted above, just make sure that the entire process from pre-cleaning on won't promote hydrogen embrittlement.
    Some of us even prefer the satin finish of the nickel over the shiny chrome.
    The nickle can reduces the friction of the hinge and if it's baked after application the hardness can be increased*. My plated and baked UZI parts are just like new after more than a decade.

    There are also DIY electroless nickle kits on the market - if you don't have a local shop to do the work.

    *depends on the chemistry of the particular nickle system.
     
  11. Oct 14, 2019 #11

    Rik-

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    Electrolysis Nickel is not shinny, Show Nickel is but both tarnish as soon as they come into contact with water and will turn from pretty to pretty ugly quickly.
     
  12. Oct 14, 2019 #12

    Kyle Boatright

    Kyle Boatright

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    These are exposed, but not in a prominent position. It wouldn't bother me if they were dull. I'm looking for something which won't rust or cause a material failure down the road. Arguably, I'm over-thinking it, but it is my party, so...
     
  13. Oct 14, 2019 #13

    Rik-

    Rik-

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    Here is an example of a polished item coated with "show nickel". It has a somewhat polished stainless look to it with a slightly "wheat" tint to it.

    Don't know if this helps.
     

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