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Tiny scratches revisited

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  • Tiny scratches revisited

    Hello all,

    This is going to be a long post, but it has to be that way for you to fully understand the frustration I'm going through. I'm currently trying to polish the aluminum front fork tubes on my bike and I'm at the point where I've given up. Monday morning, I plan to take the tubes into my local chrome plater and have them finish them because I, like others here have not been able to solve the mystery of the tiny scratches that only show up when looking at the piece from an angle.

    I have tried everything. Sanding with 320, then 400 wet and 600 wet to get a satin finish. Then, I've tried sisal wheel with black emery, brown tripoli on sisal or spiral sewn or loose cotton, red rouge on spiral and loose, super bright on loose. I've tried all sorts of different combinations of these, using various pressures of the piece against the wheel, tried heating the part with a propane torch, tried spritzing water and using talcum powder on a clean loose wheel, you name it. I've been very meticulous about not contaminating wheels and cleaning the part and my hands when switching to a finer grit.

    I've read the instructions a billion times, read every post on every thread on this subject and I'm ready to throw the whole works in the garbage because I just can't get it. I'm normally a very patient person who likes to fiddle with things and learn to do it myself, but I've spent countless (and I do mean countless) hours trying this black art and I'm no further ahead. I can't put off riding now that spring is here, so I have to wave the white flag and say uncle.

    I'm sure it's something fundamental that I'm doing wrong, but I can't see it. A video that shows exactly what the wheel looks like, the amount of compound on it, what the part looks like at every stage and every angle would be most excellent!!!

    I'm embarassed and greatly disappointed at my defeat. I guess I'm just looking for someone to say "It's ok, I've been there too."

    over and out.

    VTXer

  • #2
    Please try and post a picture capturing what you are talking about. It would be helpful. And by the way, I've been there too, I may still be there.

    Comment


    • #3
      A few questions:

      I will try to get some pictures for you. The plating thing isn't working out because all the local platers are backed up 6 weeks and I'm not waiting that long. I'm going to have to do my best and deal with it next winter if it's not to my liking.

      A couple of newbie questions (in no particular order) while I'm trying to get pictures:

      1. When I'm sanding the tubes, do I sand around the diameter in one direction only, or do I sand in multiple, or criss-cross patterns?

      2. If i go to 600 grit (any finer and I've heard you actually push the oxidation back under the surface), do I start with emery or go straight to tripoli compound?

      3. If you have too little compound on the wheel, what happens to the part? I ask this because it seems to be hard to load the brown tripoli onto the wheel. My main problem may be that I don't know what is too much and what is too little compound. Do you use a feather touch to load it up, or do you have to give it some real pressure or somewhere in between?

      4. Should you have absolutely no compound left on the part after buffing?

      5. Same question as #1, only when buffing. Do you buff in one direction only or try different directions? I've just been holding the tubes to the wheels and spinning them with my hands and slowly feeding the length of the tube to the wheel (results in a spiral pattern).

      6. I've been cleaning off any compound by using paint thinner, wiping dry and then hitting it with the propane torch to burn off any residue. Is there a better way?

      7. The loose wheels that I use with super bright (white compound) turn black after a short while. No amount of raking makes them white again. Is this normal?

      Okay enough questions for now. I will have to keep trying, I guess, but it sure is hard not to go postal after a while. After the emery, it shines not too bad, but I can still see scratches, then as soon as I hit it with tripoli, it goes all cloudy.

      I'll try to get pics, but it could be tough to really capture what's going on.

      Thanks to marsfroggie and anyone else in advance for your insight.

      Comment


      • #4
        Answers,
        1. Sanding steps don't matter unless you want that to be your final finish.

        2.You can start with tripoli after 600 grit wetsand.

        3.Very little will happen if the compound is worn, or there is not enough on the wheel. You just won't see much of anything happening to the part. Medium pressure to load the wheel, probably 5 lbs. pressure for all compounds but tripoli. Tripoli may require more pressure or wheel speed to load.

        4. If done correctly, there will be no compound residue at all on the part. I don't worry too much about that until the final step. Just clean it really good in between steps with laquer thinner.

        5.I cut one angle, then come back over at a 45 degree angle. Some people disagree and say buff only one direction.

        6.Laquer thinner or acetone will work better than mineral spirits. Laquer thinner is what I use, on a cotton terry cloth it just melts the residue away. A propane torch probably won't burn any significant amount of residue off of the part. Submerging the part in acetone would probably be the easiest way to clean, and then spraying it off with water afterwards.

        7.Yes, every wheel you use will turn black and stay that way.

        You say it gets cloudy right? You need more speed and pressure then. If you stay on it long enough, the cloudiness should go away. If the part is aluminum, it may be conducting all of your heat away from your buffing area. Therefore you should use more speed and pressure to compensate.
        I'll go take a picture of what the metal is supposed to look like when it is done.

        Comment


        • #5
          Alright, here is a picture of a part I polished a while back. That is white on a loose spiral wheel for the final finish, I'm about to do it again, as I am not satisfied with the underside. I cut some corners to get it done, but now I am regretting it.


          Http://www.geocities.com/marsfrogie

          Comment


          • #6
            Thanks, yet another question though.

            Still working on getting a picture to show. Thank you for the answers to all of my stupid questions. One more stupid question though...

            Does the ambient temperature of the wheel make a difference? I live quite far North and I have been working in chilly conditions with no heater in the garage (40-50 degrees F). I've been heating the part with a torch so that it's quite warm, but can still be handled with bare hands. The wheel, however is cold and I'm thinking that may be a reason for my compound loading problems and also the difficulty in getting rid of the tiny scratches.

            Any thoughts?

            Comment


            • #7
              Temp shouldn't be much of a concern. The edge of the wheel is the first thing to heat up. What size wheels are you using?

              Comment


              • #8
                I'm using 6" wheels on a bench grinder with arbour extensions. RPM is 3450 and seems to have plenty of HP.

                I guess I'll just keep trying to get the results I should. I'm getting really anxious to ride though. If I figure out what it is that turns my bad into good, I'll be sure to share it in case it helps some other poor unfortunate soul.

                Comment


                • #9
                  Yes, if you are swinging those wheels and they aren't bogging down you should be able to get that part to shine. I don't get it.

                  Comment


                  • #10
                    If your trying to polish then 600 is way to hard. You should step it down after each point... 1000, 1500, 2000grit. Then use a ver mild compound (3M) and finally a hand Glaze (3M Imperial). You can then lay-on a clear coat, or continue to use the hand glaze every 2 weeks.

                    HTH

                    Comment


                    • #11
                      That is too much work. Buffing wheels are much quicker.

                      Comment


                      • #12
                        #5 dont spin anything. the spiral effect is from your gloves. work it from side to side otherwise they will look like barber poles.

                        Comment


                        • #13
                          im new to this place but ive been polishing parts for 15 years now , i always found that polishing in diferent directions works the best for smoothing out imperfections * just like block sanding* because the wheel will pull and stretch any imperfection or machineing marks for that matter and make them larger but anyway what i was gona say is to give a final polish in the same direction of the length of the tubes so you dont see the circular lines from spinning them in a circle also if your working under flourecent lights dont knock yourself out over it , always inspect it in the daylight the lights always show a bit of haze i found

                          Comment


                          • #14
                            im gonna agree with spyder, i had the same problem with the lighting you really cant tell till its in normal sun light and also their will always be little scratchs in polished aluminum if put in direct flourcent light and look at it in certain angles. ive found that after buffing the part looks perfect then when i go for the final step (hand compound i use flitz from caswell) when done thers a lot of handleing scratchs which cant be avoided if you stand back you'll see the part looks a lot beter than you think

                            Comment


                            • #15
                              I am having the same exact problem.. .I cannot get those nasty spiderweb scratches/hazing away from my workpiece... should i spend a lil more time on the white rouge the only thing is which way do i rotate the piece... against the rotating wheel, or with it?

                              is it true that when u go against the wheel you cut? so it creates scratches? and when u go with the wheel u polish? is this how u rid those scratches?


                              until i get my metal to shine like chrome (no scratches(spiderweb)) , i think i've mastered it..

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