Announcement

Collapse
No announcement yet.

Filing technique

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Filing technique

    I have some stuff that I posted on the other bbs that I thought might be of interest to some here. It's about filing technique.

    This is nothing special, just the edge of a piece of aluminum angle I cut with the bandsaw from some channel. It is a near optical finish and blackout straight with the hardened SS Japanese rule beside it. I have not buffed it or polished it, that is the finish from the file. Incidentally, I do it free hand with no vice.



    Naturally you need good files. I have an assortment of Nicholson files that I bought 20 to 30 years ago. I reserve certain files strictly for use on non-ferrous metals, they never touch iron. I also have certain favorite files that happen to be exceptionally flat. You should always store your files so they aren't banging into each other.

    Filing non-ferrous metal such as aluminum is easier in that it goes faster but also has more problems in some ways because it is softer. Pinning, where bits of swarf are stuck in the teeth is the biggest problem. They easily scratch the work. I clean the file with a quick wipe on my pant leg every stroke and more thoroughly every few strokes. I occasionally give the file a swipe over a piece of chalk, this helps the swarf fall out.

    The biggest secret in filing is simply technique. This is something you learn the old fashioned way, by doing. I hold small or light parts in one hand and the file in the other. I don't use a handle as I don't hold it by the tang and the handle gets in the way. I grip the file in the middle by the edges. By hand holding the work it allows you to better feel how the file addresses the work. For the piece in the picture I was dressing the edge that I had just sawn. The two hardest things to do are to keep from rounding down the ends and to keep the file square to the edge of the work.

    This takes practice. Also, I push the file. There isn't any difference between pushing it or drawing it, it cuts the same either way. I push the file in one long smooth motion the length of the work. There should be no chatter, just a smooth sliding motion. For that piece I used a 10" mill bastard for roughing and switched to an 8" mill bastard for finishing. I do use a lubricant, but not oil. For the final finishing I wet the file with isopropyl alcohol every stroke. This works great for nonferrous metal. WD40 works well on iron.

    You must take care that the file is flat on the edge of the part and then use enough pressure to insure a smooth cut. This sort of filing accounts for the majority of the filing I do although I will also use the file in many other ways. This is probably going to change somewhat once I have my CNC mill I am building up and running. Still though, filing is one way I finish parts that are beyond the capacity of my machines.

    There are a lot of setup tricks to use as well. If you are filing the surface of a block then clamp two pieces of the same material to either side and file them all together. This produces perfectly square edges on the work piece.

    I also use a file as a sort of scraper on large flat areas. Again with no handle the file is dragged at an angle across the work and over the edges. By working from different directions and angles it will dress down the surface to a much better degree of flatness.

    The main secret, as said, is practice and more practice. I've been doing it for about 40 years.
    Free software for calculating bolt circles and similar: Click Here

  • #2
    Alright Evan ...I give up !
    The only way I can see a file doing that is to rap 1500 grade wet n dry around it following up with a rag rapped around it with mental polish.
    your files must not be conventional files as I know them ......more like lolly-pop sticks with very fine abrasive stuck to them.
    Show us dem files man!
    and a few step by step pics ...
    all the best....mark

    Comment


    • #3
      Step by step pics? All you will see is a saw cut edge become smooth and shiny. They are ordinary Nicholson files, albeit old ones that I have selected for flatness. The alcohol lube for the final finishing of aluminum makes a big difference just like it does on the lathe. And practice...
      Free software for calculating bolt circles and similar: Click Here

      Comment


      • #4
        Evan that is a fine example of draw filing. I must admit I havent achieved that degree of finnish yet. I'll try the lubricant it just may do the trick. Thanks that is good work!


        Comment


        • #5
          I'm going to have to keep a welding helmit next to the puter, that photo came close to giving me a flash
          To invent, you need a good imagination - and a pile of junk. Thomas A. Edison

          Comment


          • #6
            I've found a wood plane does a fine job truing up edges of aluminium. No mucking around, couple of licks with the plane and your done.

            John.

            Comment


            • #7
              Fine job Evan- I have filed a lot of aluminum, mostly castings where you drag up a bit of sand and that is one of the nicest finishes I have seen.-Jerald
              Maho

              Comment


              • #8
                Nice job Evan alot of people could never do that with a file. I still think that the numbers you through out at the the PM site were a little high or is it low, I dont know lol. Anyways you do incredibly nice work and I wont take away from that. Now be careful and dont drop that piece of aluminum, it would look terrible with a concrete radius on the edge.

                Comment


                • #9
                  It looks a little better than the factory extruded edge, I'll give you that. I still see some scratches and I doubt that it is square the entire length, but for an old fart...not bad.

                  I prefer Methyl Hydrate for cutting, drilling, and tapping Aluminum at high speeds because it is cheaper and you do get a nice finish. The only problem is the danger or fire or explosion they present.

                  Comment


                  • #10
                    Nuce work with the "German Shaper"
                    Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

                    Comment


                    • #11
                      Okay, who,s the "newbie" impersonating Evan and posting a picture too wide...Just kidding.

                      Comment


                      • #12
                        mochinist,

                        For a surface to act as a mirror it must have a surface finish approaching the wavelength of light. For green light that is 0.00002". This does not imply that the surface has that degree of overall flatness, just that it is smooth to that degree. This isn't that much of a job really. With dead simple tools I can make a telescope mirror accurate overall to better than 1/4 wavelength of light.

                        Thrud,

                        I thought your eyes were toast Yes, there is a little scratch I didn't bother filing out. That is because I am cutting off that end. When filing a part like this I always leave some extra at both ends since it is nearly impossible to avoid slightly turning down the end a thou or two. Isopropanol won't form an explosive vapor at room temperature. The vapor pressure is too high.

                        Boomer,

                        Sorry, I forget that some people are still running at 800x600 resolution.
                        Free software for calculating bolt circles and similar: Click Here

                        Comment


                        • #13
                          Okay Evan I will take that as a an explanation and believe it since I know nothing about wave lengths of light. When you originally posted that number in the other board I interprited differently, I thought you were saying that you filed it to an overall flatness of .00002. Hell if you just want it to be shiny get yourself a polishing wheel. I have a customer who is an artist, I sell him 2" dia by 1" long aluminum slugs that I bore a 1" hole in the center. He doesnt even want to pay to have the saw cut edge machined, so he just sands them and then polishes them. They turn out surprisingly nice looking. He puts a little clock in the center of them and sells them as paper weights.

                          Comment


                          • #14
                            My first month or so in trade school was spent with files. Man, how we envied the guys who were farther along and had actual machines to run but today I'm thankful for the time spent with those bastards

                            ------------------
                            Hoffman in Warner Robins Ga
                            Techno-Anarchist

                            Comment


                            • #15
                              That's a great example of fine craftsmanship. Too bad many here in the US didn't recognize it.

                              Comment

                              Working...
                              X