9 Replies Latest reply on May 15, 2015 10:40 AM by John Stoltzfus

    Showing a round part in a flat view for dimensinog

    Brent Belongea

      I need to show the dimensions of the holes on the tube in the flat pattern.  How is this possible to take the round tube and flatten to show the holes.  I've tried the fold and unfold, but that does not show up correctly in the round or it won't show the correct circumference when flattened.

       

      I would like to draw this on a structural member tube and be able to flatten to show the correct dimensions.

        • Re: Showing a round part in a flat view for dimensinog
          Jeff Mirisola

          It depends on when the holes are created in the manufacturing process. Assuming that they are created while the material is still flat, you'd unfold the part, create the holes, then fold it. Your flat pattern should show the holes in their correct orientation with the correct diameter.

          • Re: Showing a round part in a flat view for dimensinog
            John Stoltzfus

            There are two ways that give you two different flat patterns.

             

            1.  When doing sheet metal do all your bends then "Un-Fold" add all your cuts and then "Re-Fold" and then when you do a flat pattern the holes can be dimensioned, "However"  in the formed state the holes became ellipses and now maybe the hardware doesn't fit.

             

            2.  Do all your holes prior to bending so that when you do the form bending the hole stays concentric and the hardware can fit perfectly, "However" in the flat pattern it becomes a huge issue to dimension everything, because now in the flat state the holes become ellipses.

             

            If you are planning to have this part laser cut then I would put some reference dimensions in the drawing, however if someone needs to dimension off the drawing to make the part by hand, that is where you will spend some time,

             

            -

             

            Also see this post

             

            Feature recognition: imported sheet metal (rolled cylinder)

              • Re: Showing a round part in a flat view for dimensinog
                Dennis Bacon

                I'm guessing that you would like to make the tube in sheet metal since it would be much easier to add the hole pattern to an unfolded part then fold it and join it together to make a tube. It is my belief that there is no shape in the flat pattern that is going to result in a hole in the wall of the tube that has the walls of the tube parallel to the hole axis. This would be the case if the tube was drilled or lasered and indexing the part angular around the center of the tube. In sheet metal the outside surface stretches and the inside surface compresses. In order to accomplish a round hole in the cylinder wall the shape in the flat pattern would have to be elliptical and a nonuniform bevel thru the material. The pics below show, in an exaggerated way what it would look like.

                 

                Hole Stretch in Cylinder_4.PNG

                Hole Stretch in Cylinder_1.PNG

                Hole Stretch in Cylinder_2.PNG

              • Re: Showing a round part in a flat view for dimensinog
                Kevin Chandler

                Hello,

                 

                As stated previously, you're going to get ellipses in the flat or in the round, depending on where you do your initial hole pattern.

                 

                But, if you're just looking to get some "nice circles" for easy dimensioning on a drawing, may I suggest adding duplicate cut extrudes on a few holes (enough to establish/dimension the pattern) after you've made your "regular" holes..

                 

                If you hole patterned the flat, cut a few holes in the round (after you refold it) and dim to these.

                If you hole patterned the round, cut a few holes in the flat (after you unfold it) and dim to these.

                Just remember which were duplicate.

                 

                I haven't tried this, so the duplicate holes may be tough to select (or even unselectable) for dimensioning.

                 

                But it's just an idea.

                 

                Cheers,

                 

                Kevin

                • Re: Showing a round part in a flat view for dimensinog
                  Brent Belongea

                  This tube that we are making the part from is a standard wall thickness tube...we are not making it from sheet metal.  The problem that I'm having is when I "flatten" the piece to show the dimensions in the flatten view, the circumference is not correct, thus the dimensions in the flat view are not correct.