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rolling a cone

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  • rolling a cone

    I need to roll a cone 2" dia start, 4"dia end, 18 long. 16 ga stn stl. I'll tig the seam. I need two for some headers I'm building.
    Any ideas?

  • #2
    There's a piece of free ware out there called Cone that will generate the 2d flat surface of a unrolled conic section. Just a matter of plugging in the end diameters, angles and height. I did a Google and came up still looking but I did not go through the whole list On my ox the program is Cone v1.3
    Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.


    • #3
      Very difficult without a set of cone rolls.
      I just need one more tool,just one!


      • #4
        <font face="Verdana, Arial" size="2">Originally posted by wierdscience:
        Very difficult without a set of cone rolls.</font>
        I'll go along with that! especially with small diameters. No need for computers to get the plan, just do it on paper. That 16g SS is going to be a pain to roll with out the gear though


        • #5
          There is some other software called SheetMagic. It is for making anything out of sheet metal. Very good. Opens the shape up for you then you can print it 1:1 if you want.


          • #6
            Sorry that was called Sheetlightning


            • #7
     don't need any software.

              Just 3.14 x 2 = 6.28"
              Then 3.14 x 4 = 12.56"
              Then 6.28 x 12.56 x 18" is the size blank needed,no sweat because the errors are "mig weld"tolerable.

              But it will be a PITA to roll.One method you might try is to make incremental bends in a wing brake.But,from experience I can say that it is much easier to use this method by making the part in two pieces.
              I just need one more tool,just one!


              • #8
                start with French and Verick "Mechanical Drawing" and add about two years of hectoring and nagging by Bob York the apprietice school drawing instructor and you can draw anything. It's been 40 years and I can still instantly run through the steps of sheet metal layout in my head. What ever than man told you: stuck.

                Now, if if could only remember Barbara's name when I introduce her to old acquaintances.

                Rolling that cone will be a trick especially so the ends lie on the surface of the cone. There's a sheet metal trick to fix that. What is it?


                • #9
                  It's not hard to get more accurate than that either. Draw a plan of your cone (2D) then extend the sides up till they intersect. Then get out your compass (dividers) draw an arc with the intesection as the centre and the arc from the top line of the plan of your cone, then do the same from the bottom of the cone. (use string or a tremmel if to large for compass/dividers) Now draw a half circle on the bottom of the cone plan. This gives you a half circle of the large diameter of your cone. Divide this up into some smaller even sections say 4 then measure one section with your dividers. Then step this distance out 8 steps along the large arc. From there draw a line back to the intersection. Now you have it.

                  Hope this makes sence, a picture would have been easier

                  Making cones is fun. Rolling them is a pain. The 2 half idea is a good one. If you do the plan as discribed above. Marking extra evenly spaced lines from the intersection and using these as incremental folds may help.

                  [This message has been edited by zl1byz (edited 08-10-2004).]


                  • #10
                    <font face="Verdana, Arial" size="2">Originally posted by Forrest Addy:Rolling that cone will be a trick especially so the ends lie on the surface of the cone. There's a sheet metal trick to fix that. What is it?[/B]</font>
                    If using rolls you need to form the ends first. IF you don't the ends remain flat for the distance between the rolls. The other way around this is to roll a longer peice of material than nessesary, so it over laps then you can cut the flats out.
                    With such a small radius it will be hard enough rolling the correct amount without over lap getting in the way.

                    [This message has been edited by zl1byz (edited 08-10-2004).]


                    • #11
                      To lay out the flat cone:
                      Draw an arc w/36in radius and 3.14x4in long
                      Measure 18in from end of arc along radius and mark
                      From center draw arc through mark to other radius
                      This is the flat shape.

                      Leave extra material on each radius side so bend can be formed. Remove after shaping.

                      A decent sliproll and a little patience will go a long way toward end shape.



                      • #12
                        Use this program to lay it out.
                        Without a set of roller the easiest way would be to turn a former up out of a piece of scrap or even a few pieces welded together and form it round.


                        John S.
                        Nottingham, England

                        Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


                        • #13
                          Laying out the part is not my issue. I have the part designed in Pro-E and have unfolded the cone, so I no what I need in the flat. I guess I should have asked about the rolling.
                          tapered roller sounds like the way to go. But do not have. May have to farm this one out.


                          • #14
                            I am not well versed in sheet metal rolling. I've only done a couple of jobs and they were cylinderical, not cone shaped. So don't yell too loud if this is completely off.

                            When you roll sheet metal, the spacing of the third, opposing roller determines the radius of the curve. I have misadjusted the two ends of this roller on my sheet metal machine and produced a slight cone shape when it was not wanted. Couldn't this allow you to roll a cone with three straight rollers. They would have to be relatively small diameter, perhaps 1/4 the diameter of the small end of the cone or less. The two fixed rollers would be spaced a bit apart and parallel to each other as is normal. The third, opposing roller would have to be set lower into the fixed ones on the small end of the cone. This should produce a perfect cone.

                            All you need is a machine that fits these specs. Likely have to build it. But it need not be overly complicated unless this is a recurring job.

                            Paul A.
                            Paul A.

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


                            • #15
                              Rolling a cone with a set of slip rolls is not a big problem. It is done basically as Paul and others have stated. The problem in this case is the size. With 2" on the small end you will be rolling almost to the smallest diameter possible with a 2" roll diameter unit. This leaves you with not material to over roll for springback of the material. If you have a machine with 1" rolls you will be pushing the capacity of the machine with 16 gage stainless steel. The springback on stainless in 16 gage is significant.

                              Having said that if I were going to try to make this piece with a 2" roll set I would set up the machine and roll for the 4" diameter cone end with as much of a cone in it as I could get on the 2" end. It may be 2-1/2 to 3" or so on the small end. Remove the piece from the machine and using some type of ring clamp force the ends of the cone together and weld them together. Tack it in a few places along the length of the seam. Ring clamps could be made from anything from a pair of u bolts to heavy wire and twisted together. Depending on the accuracy needed on the ends you may want to made a wooden plug 6" or so long to fit the 2" end of the cone to help control the shape when you clamp that end.

                              I have never tried this but if you have a Magabend brake you might be able to for the piece around a round bar if you laid out the brake lines. I have formed 24 gage stainless pieces using a 1-1/2" diameter piece of round stock for counter top covers using the magabend. I works great. If I had some 16 gage stainless I would try to make one. I am very curious. The only stainless sheet I have is 24 gage.

                              Good luck with your project.