Making angles in a tube (cilinder)

DELFTship forum General Questions Making angles in a tube (cilinder)

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    • #44152

      After years ago only drawing an hull of a Steamboat to use in Sketchup, now its my first complete boat drawing.

      Now I need to draw a rail. Its a flat strip, with a round pipe at the outside. Where this rail ends, the Pipe makes an 90′ angle to be welded on the superstructure.

      What is the best way to make an angle / corner in a tube (stredged Cilinder) ?

    • #44160
      Terrance Egolf

      Hi ketelbinkie.

      This forum’s web client is pretty broken, so I won’t even try to post images in my response. If you want to contact me directly by email so I can share some useful images, please use the address I included in my response #44109 under the topic “Introduction of a newcomer!” on May 3, 2021 at 15:18.

      Here goes:

      I assume you have created a cylinder for the rail using the 3D primitive tool found on the Tools Ribbon (located all the way to the right on the ribbon). It should be oriented parallel to the X-axis of the model.

      Next, using the same start and end radii used in the railing cylinder, and the number of points (6 is the minimum—I usually use 12—but the number of points has to match), orient the new cylinder’s Startpoint and Endpoint parallel to the y-axis. This means you only change the middle set of coordinates (the Y-coordinates) for each point in the Cylinder dialog. The other Startpoint and Endpoint coordinates remain the same. I would enter the Startpoint Y-coordinate at, say, 10 feet or 3 meters, and the Endpoint Y-coordinate at, say 9 feet or 2 meters (the actual numbers don’t matter at this point in the process—the second number should just be smaller than the first). Then click OK.

      When the new cylinder is visible, it should be perpendicular to the railing cylinder. You may have to select and drag it to the vicinity of the railing cylinder to help make the connection.

      Next, you will have to cut matching 45-degree bevels in the corresponding ends of the rail cylinder and the new one you just created. This will require creating an X-Z or Y-Z vertical plane that is placed on a separate layer from the other geometry visible in the model. (I usually call this the Auxiliary layer—use the Add button in the Layers Menu Group to create a new layer.) The vertical plane needs to be large enough to completely intersect the cross-section of the cylinders when rotated to make the cut.

      Using the Rotate Transform on the Tools ribbon, rotate the vertical plane so that it swings 45 degrees around the Z-axis. (There isn’t enough space or time to describe how to do that in this post! Email me for instructions, if needed.)

      After rotation, move the plane so that it completely intersects the new cylinder near one end. It MUST intersect all the side edges of the cylinder for the intersection to work.

      Go back to the Home Ribbon and click on the Intersect button in the Point Menu Group. For the “Insert new points in” box, select the layer the cylinder is in. For the “Find intersection with” box, select the layer the Auxiliary cutting plane is in. Click OK to insert the new points and edges in the cylinder. If it works correctly (many times it doesn’t!), there should be a new edge oriented at 45 degrees from the axis of the cylinder. Important! ESCAPE TO DESELECT ALL EDGES. Then delete the unwanted faces to create the 45-degree bevel.

      Repeat this process for the railing cylinder (assuming it is exactly parallel to the model’s x-axis). Delete the appropriate faces to match the short cylinder’s bevel.

      Select and drag the short cylinder over to the railing cylinder, and align it perfectly to the corresponding edges and control points along the bevel.

      Making sure that both cylinders are assigned to the same layer, delete (only) one of the adjacent faces on one of the cylinders, then rebuild it by connecting to the other cylinder’s corresponding control points. Repeat until all the faces are joined at their shared edge.

      When you are finished connecting the two cylinders, make sure that the edge defining the bevel joint is turned into a crease edge so that the bevel forms a sharp corner.

      Sorry that this explanation is so long-winded. If there is an easier method to do this, I hope someone else jumps in to provide it.


      P.S. For the moderators, videos demonstrating how to rotate objects and to create intersections would be good topics.

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