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Restoring the shine to machined surfaces?

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  • Restoring the shine to machined surfaces?

    I'm in the middle of refurbishing both that shaper and mill I've mentioned in the past couple of weeks. Work's going well, but slowly (that pesky day job...!)

    The clean parts and new paint are really making a difference, but I'd like to also shine up the ways and tables if I can.

    Now, they're not "rusty" (for the most part) they're just tarnished. That dark, oxidized tone that old steel gets. However, being the machine ways, obviously I shouldn't just take a belt sander or a scotchbrite wheel to 'em. Specifically, there's still a lot of the original flaking/scraping evident on the mill ways, and I don't want to just wire-brush that into oblivion.

    I tried some Naval Jelly, both by itself (with a rag) and with some fine steel wool. That definitely brightened the metal a fair bit, but it's still a very long way from new-looking.

    Is there any trick that can do this?I know it'll never be "freshly machined" new-looking, but right now, they look almost gun-blued, especially in contrast to the new light-grey paint.

    Doc's Machine. (Probably not what you expect.)

  • #2
    Doc, you probably know this already, but the Scotch-Brite hand pads are available in all different grades, including a 7441 grade, or 'Type T' ,which is non-abrasive.
    The white 7441 pads are very good (if hard work!) for removing tarnish without really removing metal.
    More info here:



    • #3
      I used the maroon colored Scotch-Brite pads and WD40, or K1 to clean my lathe...worked pretty good for me.


      • #4
        Because cast iron has grain, its hard to get rid of all staining without removing metal which you should not do on way surfaces. In some cases, even other machined surfaces are parallel references on which you might put an indicator or something, so I wouldn't get carried away with abraisives there either. Even on way surfaces, one might argue that abraisives are a bad idea (and they do require very thorough cleanup to remove all traces that might otherwise lap your way surfaces for the next decade). The flip side of this however is that a slurry of iron oxide is abraisive in its own right, so polishing them up a bit may save wear in the long run.

        As previously stated, Kerosene and gentle application of a scotch brite pad work wonders. I have then followed with a polishing with Flitz metal polish. Before I get lectures on this, I always clean the remnants back off with kerosene. Its also important to note that flitz is a micro polish and will tend only to shine the surface of metal without changing it dimensionally. I use this on non-way surfaces to give a shine back to the cast iron.

        Way surfaces will tend to be somewhat self-polishing. What I have done is to use the same medium-fine slip stone I use in scraping work on a way surface...very gently. You use it just enough to show up the high spots from dings. I then use a scraper to knock them down. Stoning can also do the job...but keep the stone moving around so you are not just making a low spot in the ways where there used to be a ding. A high spot on one way surface will become a groove on the other over time so removing them is the lesser of two evils.

        Paul Carpenter
        Mapleton, IL


        • #5
          Be careful with the Scotchbrite Maroon pads -- they're 380 grit aluminum oxide, and they definitely remove metal. Take one to a piece of mild steel and you'll see what I mean.

          I use the grey pads, which are one step down from the Scotchbrite White, but a lot gentler than Maroon. I think Scotchbrite Grey is 600 or 800 grit.

          By the way Doc, SPI distributes "Knorrostol", which is a fine machine polish made specifically for precision surfaces. It's Made in Germany, and it works great to remove the black patina from rust, oil varnish, or coolant stains:

          "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."


          • #6
            Fastenal polishing wheel

            Recently I was helping out at the Heber Valley Railroad and we were cleaning up several recently aquired machine's and tooling. We used a wheel mounted to an angle grinder to clean up the light rust from the machine ways and tables, sorry I do not recall the brandname on the wheel but I do know they are available in more than one version (Version's are more or less agressive) the wheel we used was YELLOW and I'll admit to being very surprised at how it removed the light rust, dirt, baked on oils, and stains - MOST IMPORTANTLY it did not remove one bit of material! Really when finished the original scraping and machining marks remained - only a bit brighter.

            I'd sure take a serious look at these wheels, Fastenal is a widely based outfit and they may be available elsewhere - where I cannot say but they must buy them as they are not manufacturers of these wheels.

            Good luck


            • #7
              I have prettied up a few machines, including a shaper. I dont even want to remove metal so I go at it by hand. And I love the scotch bright type pads. I have all sorts from very soft to almost stiff like a piece of wood.

              For that application I would use the softest and cheapest one around. Harbor freight "green weenies" GW is a term I heard in the navy for those cleaning pads. Anyway, they are really soft, no worry about removing metal with them cause you are hand cleaning them. And the benefit of using yer hand is the fingers will apply just as much pressure in the "recessed" parts of the scraped area. All yer looking to do is clean the area. The fingers are the best.. VS a air or electric rotary tool where it is gonna skim the top surfaces of the metal and leave the lower ones dirty until you grind away the higher surfaces!!! Which you DONT want to do.. JR

              Oh, the solvent I use is good ol WD40. Cheap by the gallon and works well...
              My old yahoo group. Bridgeport Mill Group



              • #8
                Try Cratex.
                it is a very fine rubberized abrasive.
                Green is course
                Brown is Medium
                Gray is Fine.
                Thats what professional restorers use.



                • #9
                  no one else has said it so i will; just leave the surface as is. It accomplishing nothing tarting it up and potential could damage - who wants all kinds of abrasive products around the machine anyway? Put those finishing efforts into work pieces.


                  • #10
                    From this .

                    To this

                    First step use hydrochloric acid (15 percent concentration ...maconery cleaner)...mixed with wall paper paste
                    leave it soak for ten Min's
                    neutralise with bicarbonate of soda
                    *****if you use scotch brite ...all the little dings and frosting shallows will be over-ridden and remain dark, hence the acid*****

                    Dry off and

                    Then polish with one of these ...
                    with finest car paintwork cutting paste ...

                    Scotchbrite also more abrasive then what Ive done .

                    Hope this gets it there

                    all the best.markj


                    • #11
                      no one else has said it so i will; just leave the surface as is. It accomplishing nothing tarting it up and potential could damage
                      Because I like to be able to take pride in my tools and craftsmanship.

                      I suppose I could have just pressure-washed the whole, fully assembled mill, pumped some new grease in here and there, and then just used it 'til it wore out, but that's not the kind of guy I am.

                      The finish was shot- both the original paint and the two, possibly three layers of paint applied later- the paint and grime hid quite a few surprises (like the corks filling drilled holes in the casting) and there were several minor issues that I'd have never noticed or fixed had I not disassembled the thing for a thorough service.

                      And again, now that the paint and other parts are being slowly returned to bright and shiny, I'd like to improve the machined surfaces to match. It's like putting a $6,000 paintjob on a lowered and smoothed '57 Bel Air, but then leaving the old steel hubcap rims and bald bias-plies on it.

                      If I have no other options besides mechanical metal removal (as in abrasives) then I'll do the best I can with Navla Jelly or metal polishes and leave it alone. But if I have a chance to brighten the surfaces, why not spend the few extra minutes?

                      Doc's Machine. (Probably not what you expect.)


                      • #12
                        Naval Jelly will leave a gun blued looking coating. It will also protect the metal, and is attractive in a way on some parts. It is also a great finish for painting.

                        I have used the scotch brite pads a lot, and if used with care I don't think they will cause any problems. The best bang I have found for a quick "polish" with no metal removal is a very very fine stainless steel wire brush, you can clean under you finger nails with it, that's how fine it is. I would get stainless in the brush, as brass, and regular wire can cause problems (transfer) you can kinda rake the stainless brush out on a piece of stainless if you need to clean/polish a piece of stainless. Use a drill to power the brush, Mcmaster has the brushes, also do wear safety glasses.

                        Hope this helps, Clint