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  • Metal Warping?

    Hi Guys,

    I recently purchased a slotting saw and used it this morning. I secured a piece of 1/4" thick aluminum sheet-metal in the milling vise and cut a slot 7 inches in length. It was doing a fine job so I decided to continue and cut through the sheet producing a narrow strip of metal 0.500" wide X 1/4" thick X 7" long.

    yThe strip bowed instead of remaining flat. I assume bowing is caused by internal stresses within the metal strip. The question is, how do I get the metal strip to go back to the original flat condition? I've tried several things but nothing has worked. Will heating remove stresses and *cause* the strip to "relax" and return to a flat position?

    Harold
    For those having fought for it, Freedom has a flavor the protected will never know.
    Freedom is only one generation away from extinction.

  • #2
    I would venture that you bought 5052 or wrought 6061, and not cold finished 6061-T651 that had been artificially aged and solution treated.

    The aluminum needs to have the stress relieved BEFORE you machine it. Try heat, you got nothing to lose.

    Comment


    • #3
      Are you able to cut it on a table saw????? I know sometimes if you sheer narrow strips they will curl and / or twist depending on thickness but as to why that is happening when you cutting it on the mill is a good question. What size slotting cutter are you using?????? The only thing that I can think of is that your loading chips between the cutter and the two halves of alum. and that is forcing the strip to bend as you move along.

      JL............

      Comment


      • #4
        The metal is 6061 T6 aluminum. I suppose it can be cut on a table saw but greater accuracy is achieved using the mill. This piece was to have been used in a slot on a grinding table. My plan was to secure the piece to a 1/4" thick plate that's 6" wide X 7" long. The plate would slide front to back on the table top and be guided (held in register) by the piece (strip) that rides in the table slot.

        I have been thinking of one last possibility. I might be able to add JB Weld between the strip and plate and clamp (compress the bow) the two pieces together thus eliminating the bow. Perhaps wait 24 hours then unclamp with hopes the cement will hold long enough for me to sink six to eight screws thus holding the guiding strip in juxtaposition to the plate.

        Do you think that JB Weld might hold the strip flat when the clamps are removed?

        Harold
        For those having fought for it, Freedom has a flavor the protected will never know.
        Freedom is only one generation away from extinction.

        Comment


        • #5
          Drill and countersink the holes in the plate. Then put the bowed strip in the mill vise on parallels, seat it flat with a dead blow hammer and drill and tap it. With it still in the vise, screw the parts together. Done!

          The part bows due to internal stresses that were released when the part was freed from the parent material. Usually the best way to straighten is overbend it the other way a little at a time in an arbor press. Check often with a straightedge and selectively work on the areas that need more.

          Comment


          • #6
            What I would do, since this is giving you trouble is cut it part way through on the table saw, just to score maybe .010 per pass half way through and then bend it back and forth until it breaks off, then mill it to finish width. Just allow yourself an extra 1/6" or so. 6061 shouldn't curl up. What is the width of your slotting cutter???

            JL..............

            Comment


            • #7
              The width of the slitting cutter is 3/32". Both ideas of either using the arbor press or making cuts in the metal are viable options of which I had not considered. I like both approaches.

              The images shown below may help to visualize some of what I am wanting to do.

              The bow is shown in the first image. The greatest amount of bow is 2.5mm. The second images shows the grinder’s table and slot.
              Harold





              For those having fought for it, Freedom has a flavor the protected will never know.
              Freedom is only one generation away from extinction.

              Comment


              • #8
                Try slotting or cutting it with a thinner jewelers saw. I think what is happening is there is some stretching of the alum. due to the width of the cut and that is causing your cut strip to bow. You may be pushing through more than cutting through the material. Also I would wet it down with WD 40 as you cut. I don't know what your DOC is per pass.

                JL................
                Last edited by JoeLee; 03-09-2015, 10:27 PM.

                Comment


                • #9
                  Which edge is facing the camera in this photo, the 1/4" edge or the 1/2" edge?

                  Paul A.

                  Make it fit.
                  You can't win and there is a penalty for trying!

                  Comment


                  • #10
                    Hi Paul,

                    The 1/4" edge is facing the camera. If I could push that down only 2.5mm and get it to stay then I would have it. That's not gonna easily happen. Will either have to slot the rail that's bowed or bend like suggested ...... or possibly a little of both. Once the bowed piece is closer to the plate, JB Weld will easily hold the track-rail in place allowing me the opportunity to drill and tap all the holes.

                    Harold
                    For those having fought for it, Freedom has a flavor the protected will never know.
                    Freedom is only one generation away from extinction.

                    Comment


                    • #11
                      Why do you have to remove the clamps before drilling and tapping operations?

                      Comment


                      • #12
                        Originally posted by elf View Post
                        Why do you have to remove the clamps before drilling and tapping operations?
                        The clamps I have are too large to fit on my table and mill vise.

                        Harold
                        For those having fought for it, Freedom has a flavor the protected will never know.
                        Freedom is only one generation away from extinction.

                        Comment


                        • #13
                          Hi Harold,

                          I would stay away from any heat to try and bend the aluminum. It would be WAAY too easy to end up taking all the 'heat treating' out of it and ending up with dead soft aluminum. Not very wear resistant if soft.

                          If you try the arbor press method (my first choice) I would use as hard a pieces of rubber at the ends & middle - something like auto tire hardness. The ram of the press and the supporting blocks might leave dents otherwise.

                          Another trick that will definitely work is to use a smooth, shiny ball end of a ball peen hammer and by supporting the side you show as the top on a flat piece of steel, tap the opposite side all along the center towards each end making sure the supporting steel is directly below the hammer.

                          The idea is to lengthen the bottom side by squeezing/stretching the metal a small bit on one side only w/each tap. You are not trying to bend the metal with the hammer. This will leave small dimples but that side can become the one in contact with your larger plate.

                          You may be surprised just how easy it is to move the metal with rather tiny dimples, not by blasting away on it.

                          By supporting the 'long' side on a flat surface, you are assured of distributing the forces and concentrating the stretching on the side where you want it.

                          I've straightened 2.5 inch diameter SS shafts this way w/o resorting to a massive press.
                          Last edited by jhe.1973; 03-10-2015, 04:06 AM.
                          Best wishes to ya’ll.

                          Sincerely,

                          Jim

                          "To invent you need a good imagination and a pile of junk" - Thomas Edison

                          "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

                          Comment


                          • #14
                            Turn strip upside down, position and clamp at each end drill and tap in the middle - then work outwards until the clamps cannot be used!

                            Peter
                            I have tools I don't know how to use!!

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                            • #15
                              Hey Guys,

                              I tried the "arbor press method" and it worked well enough to permit drilling and tapping. All went well and my project, though not complete, is on the way to completion. Once the rail was installed I squared all four sides of the plate with the rail and everything fits nicely. The next phase is to fabricate a protractor which will allow me to obtain various angles for grinding my lathe bits.

                              Many thanks to all for helping me to get to this point. ALL suggestions were very helpful and much appreciated. With further progress, I'll post my results.

                              Thanks,
                              Harold
                              For those having fought for it, Freedom has a flavor the protected will never know.
                              Freedom is only one generation away from extinction.

                              Comment

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