2 Replies Latest reply on Aug 28, 2009 12:10 PM by Jason Corl

    Belt for 2 fixed pulleys and 2 flexible tensioners

    Jason Corl

      I'm trying to create a belt with fixed length that runs between 2 fixed pulleys that each have a tensioner.

       

      Using the assembly feature for creating a fixed length belt only seems to allow for using one flexible tensioner as it would not work with 2. As soon as I fixed one it worked fine.

       

      To get around the assembly feature's aparent limitations I want to try modeling the belt with conventional methods but cannot seem to fix the belt length when it consists of 4 straight segments and 4 arcs. Pulley center-to-center and diameter, tensioner diameterand belt length are fixed. The main thing i'm trying to do is set the tensioners so that the belt runs parallel through the mid sections.

       

      I tried using an equation to derive the length of the mid section on tensioned side driven by all other lengths...didn't work, over-defined sketch.

       

      any ideas? Did I miss something in my constraints?

       

      Thanks,

       

      Edit:

       

      I have tried the assembly belt feature a few more times and noticed another problem i'm having. I have one fixed tensioner (just for testing) and one with only 1 DOF. When create the belt path by selecting the appropriate pulleys and tensioners and then "try" to select "driving" belt length...I get an error saying that for driving belt length "at least one" of the components must have at least one DOF. Problem 1: one and only one of them do have 1 DOF. Problem 2: the error message says "at least one" hinting that it will accept 2 tensioners with each having 1 DOF...but I can't get it to work with a driving length.

        • Re: Belt for 2 fixed pulleys and 2 flexible tensioners
          Jason Corl

          It seems like people are viewing this thread but not commenting so I'm guessing that means one or all of the following:

          1. I did not ask my question clearly
          2. I did not title the thread properly
          3. I did not post to the correct section of the forum
          4. Nobody else has experienced this behavior or needed the feature/s

           

          If it is something that I've done, I would like fix it to both help the forums as a resource for others and get an answer for myself. Any suggestions?

           

          Thanks,

          • Re: Belt for 2 fixed pulleys and 2 flexible tensioners
            Jason Corl

            Update:

             

            I asked this same question on www.SolidJott.com and received an response from Lou Gallo in less than an hour. Using his suggestions I was able to use a workaround.

             

            What I learned:

            1. There seems to be a bug in the belt/chain tool when working in 3D
            2. The belt/chain tool also works for sketch blocks, although I have used sketch blocks before I do not use them often and did no attempt this method prior to Lou's suggestion
            3. Using the sketch blocks worked for me. I was able to accomplish similar goals but did not retain all the functionality of using the actual 3D parts in that if I update my assembly pulley positions or sizes it does not automatically relfect on my belt tensioner locations.

             

            thanks for the help Lou for getting me through this issue and on to discover the next.

             

            If anyone has suggestions or experince with the original question I would still like to know if i've misused the tool, or if there is a way to drive the length of the sketch when driven dimensions are involved in the calcualtions.

             

            Thank You,

             

            Jason