Vice leaving "ghost image" on mill table.
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  1. #1
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    Default Vice leaving "ghost image" on mill table.

    I leave my Kurt vice on my mill table for fairly long lengths of time. When I do take it off there is always a black ghost image of the vice on the table which is fairly hard to remove. It almost seems like some kind of electrolysis. Has anyone seen this before and if so have they tried to prevent it?

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    Doesn't matter for accuracy so I wouldn't worry about it.

    We spray down the table with lps 3 rust inhibitor for good measure.

    Sent from my Pixel 3 using Tapatalk

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    No sir but I do get staining depending on the metal. Sounds like alot of SS or some kind of steel is cut in your machine. I only get black marks from steels in my cnc's.


    I'm a wd40 and stone kinda guy...

    Sent from my SM-G950U using Tapatalk

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    You need an exorcist. I found mine through Craigslist, she did a great job of removing the ghosts, and also found out why the Z servo was acting up. Who knew they taught machine repair at Psychics school?

    It's typical, my mill and Kurt vises do the same. Plenty of other posts here too on the issue. Boeing Boeshield comes up as an answer, and I've seen grease coatings, etc.

    If you run coolant, it's probably a good idea to pull the vises every couple months, clean, and add a fresh coating of whatever lotion works for you.

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    Yup,
    We get the same thing especially if we run lots of coolant.

    I also do the wd and stone thing every couple of months. And don't forget to do the bottom of the vise mounting surface while you're at it.

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    Hey Milland....Are you saying I need "Witch Doctor 40"?

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    I get the same thing on all my cnc mills. If I plan on leaving a vise on for a while I will wipe it down with a coat of grease.

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    Yup. Just the way it is........if you don’t want the marks, don’t put a vise on the table.

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    Quote Originally Posted by crossthread View Post
    I leave my Kurt vice on my mill table for fairly long lengths of time. When I do take it off there is always a black ghost image of the vice on the table which is fairly hard to remove. It almost seems like some kind of electrolysis. Has anyone seen this before and if so have they tried to prevent it?
    .
    in over 40 years never not seen any rust, discoloration when vise or fixture left on for long periods of time.
    .
    some spray oil or a asphalt or tar/mineral spirits mix which when dry forms a wax like coating of <.001" normally. it will only slow down rust. depends on coolant mix which often has a tendency to slowly dissolve oil, grease, tar and even many paint coatings
    .
    nylon abrasive pads will remove rust relatively fast. sure by hand it might take a minute where when on a air sander it could be 6 seconds to remove
    .
    nylon abrasive cloth or srubbing pads will remove soft rust 100x faster than hard metal. sure it will rough up a mirror finish but never seen machine table with a mirror finish

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    This is not rust guys. It is black and almost looks like anodizing. That's why I was wondering if it could be some kind of electrolysis. I can remove it with a little effort with Scotchbrite. I just think it's weird.

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    Happens on my table. My thought was that the oil from the head and cutting operations is sucked under the vise.
    I remember somebody telling me to use white butcher paper between the table and the vice. I'm using something
    different which is porous so the problem remains.

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    Quote Originally Posted by crossthread View Post
    This is not rust guys. It is black and almost looks like anodizing. That's why I was wondering if it could be some kind of electrolysis. I can remove it with a little effort with Scotchbrite. I just think it's weird.
    all dissimilar metal alloys when wet get electrolysis corrosion. of course all metal has particles of different elements. cast iron being carbon, iron, iron carbides, iron oxide (slag), other elements like manganese, silica, etc. electrolysis is a type of oxidation where more active metal is pulling the oxygen from molecules of less active metals. even cast iron is a mix of many elements
    .
    you can brush electroplate a nickel or cobalt or other alloys if you wanted too. it like a electric magic marker but it only applies thin .0001" or .0002" coatings. if you wanted thicker coating or to fill scratches it can take much longer. i used to fill scratches in chrome plating on printing press rollers with gold. its soft and easy to lap or sand flush with surrounding surface. obviously gold is not cheap.
    .
    some use copper plating its cheaper, easy to machine. printing press rollers or cylinders have many coatings electroplated on. hard chrome usually the top plating or coating. cobalt plating is faster than nickel, harder than copper. also used to plate worn bearing journals back to size
    .
    intergranular stress corrosion is a type of corrosion that follows into surface along grains of different crystals types. just saying corrosion you see on surface actually goes into microcracks often unseen to unaided eye. certain chemicals can even attack stainlees steel where welds become brittle over decades of exposure.

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    Water based coolant!

    If you want to eliminate it, just use coolants that don't have water in them. Or, take the vise off at the end of each day's work and clean the table with an oily rag.

    Perhaps some water based coolants are formulated to avoid this, but I am not aware of which they might be.

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    Quote Originally Posted by EPAIII View Post
    Or, take the vise off at the end of each day's work and clean the table with an oily rag.
    If Arnold had a machine shop that's what he would do to stay nice and strong.

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    Tom posted useful info on the metallurgic origins of some marks, but there's also biological - some anaerobic critters wills start growing in the low-oxygen environment of the vise to table gap, and as they do their little critter things (eat, mate, die), they'll create small amounts of acids that start etching the surfaces.

    I suspect your black areas are acid etch marks. Very light as long as the coolant isn't allowed to get too funky, and cleaned up by the usual methods.

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    Worked in a larger aircraft machine shop in my past, we were having problems machining wing skins. Seems some areas were perfect and some were too thin.
    Since we had machined the fixture on that machine it was “assumed” flat.
    When we finally checked it found it bowed causing thin areas.
    Decided to pull the fixture and found that an algae type growth had built up pushing a 2” thick aluminum plate up a few thousands.
    Cleaned by a quick acid dip and rinse, bolted down and back in business.


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