6 Replies Latest reply on Mar 22, 2018 5:16 PM by Scott Giffin

    How do I draw a Taptite thread correctly to scale?

    Scott Giffin

      I work for a bolt manufacturer and we want to draw the part print correctly to scale for a Taptite thread. It's slightly triangular and changes in size at the end of the bolt. I was able to sketch the path for the profile to follow but now it wants to twist as it follows the path. How can I get it to follow the trilobular path but stay straight?

        • Re: How do I draw a Taptite thread correctly to scale?
          Scott Giffin

          I found a couple places that suggest a way to keep the profile from twisting along the path.

          Eliminating twists from sweeps along a 3D curve
          https://www.youtube.com/watch?v=U5WRfuWPhJE

          This technique is illustrated here:
          http://blogs.solidworks.com/tech/2015/02/advanced-sweep-feature-techniques-in-solidworks.html

          When I tried this solution I was then able to select "None" under the Twist option but I'm getting an error when it comes time to create the sweep. "Rebuild Errors" "The intermediate profile #2 could not be solved. Consider editing the relations and dimensions of the original section sketch." See attached screen shot of the settings when I get the error.

           

          I also tried changing the sketch plane to be perpendicular to the front plane instead of the end of the path to see if that would help. I get the same error message. I have attached the model with this new sketch suppressed.

           

          Can some kind sole please tell me where my error is? Thanks!

            • Re: How do I draw a Taptite thread correctly to scale?
              Paul Salvador

              Hello Scott,.. well, luckily you're working with 2017 so the options are very good for such a long twist (in the past it sukd).. if you use the Natural option which was good.. but, there are a few things.. first, the profile has those 2 very small radii.. just omit them for now... and personally, I'd change the tri-lobe sketch to be smooth FitSpline... and also use the first sweep as the path (trim using the smooth tri-lobe.... also,  you should use Pierce Relations for your profile/path.. and don't over constraint (using horizontal/vertical (make them parallel/perpendicular).  (image/file attached)

              trillobe1.png

                • Re: How do I draw a Taptite thread correctly to scale?
                  Scott Giffin

                  Hi Paul,

                  I love what you've accomplished with the thread. You got a lot further than I did. The extra constraints you mentioned were my attempts to try to keep it from twisting. I tried adding an extrusion up the center to get the root radius in but it wouldn't do it. I even created a separate part and combined them making sure they overlapped completely and it still wouldn't let me add a radius. I've drawn some pretty complex features in the past but this one is being really stubborn! I've had to move on to the next job to hit the due date but I'm not done with this one. I'm going to keep at it until I get it right. Thanks for the help!

              • Re: How do I draw a Taptite thread correctly to scale?
                Kevin Pymm

                Scott,

                You can go to McMaster-Carr & download one of their examples in SolidWorks format & see how they have done it. First link is to Taptite screws, second is to a specific screw, Black Ultra-Corrosion-Resistant Steel, 0-80 Thread, 1/8" Long.

                Hope this helps.

                 

                McMaster-Carr

                 

                McMaster-Carr

                 

                  • Re: How do I draw a Taptite thread correctly to scale?
                    Scott Giffin

                    Kevin,

                    Thank you for taking the time to suggest that option. Those models are not drawn correctly. They can't get the required dimensions needed to create these parts completely. More than that, they missed some very important features of these parts. The crest of the threads are not supposed to be flat on either the high or low spots of the trilobes. They also used a 60 degree included angle instead of a radius for the thread profile. There are specific requirements published by Reminc (you need to log in as a supplier to get them) that must be followed to the letter to produce the part. There are 3 different required trilobular sections each with their own separate forms. I need these dimensional requirements to be present on my model because they will show up on my detail print for the manufacturing drawing. Since we are the manufacturer of this product, the dimensions must be exact including all tolerances. The model I supplied is only one small piece of the part and is only shown as a demonstration of the modeling process.