5 Replies Latest reply on Nov 3, 2009 12:12 AM by 1-8BS66F

    Linear Pattern Using 2 Guide Curves

      I am attempting to use a variation of the linear pattern feature that will allow me to duplicate cross-braces of a 3-legged tower along two legs.  Each leg has a centerline going up the tower legs where the tower face plane tangentially intersects them.  When I  use one centerline with linear pattern, the copy of the cross-brace extends beyond the opposite leg (unused centerline), whereas I would like both sides of the cross-brace to remain coincident with both leg centerlines.  To do this, I need the left two coincident points of the cross-brace to remain on the left tower leg centerline and then also need the right two coincident points to remain on the centerline of the right tower leg.  Is there any way to do this??? [see attached file]



        • Re: Linear Pattern Using 2 Guide Curves
          Neil Larsen

          ok I dont think linear patterns are useful here because of the taper.

          how I'd do this is using a defining sketch of XX on the face plane for some L weldments and trim them appropriately

          circular pattern 3 instances of the resultant bodies around the tower as you were doing

          if you construct it intelligently your configs should deal with any weldment/dimension variations.

          I guess you have your reasons but the rounded ends seem a little luxurious...dunno


          anyway HTH

          • Re: Linear Pattern Using 2 Guide Curves
            Matt Lombard
            Actually, the Vary Sketch option is what you need. When you use a Vary Sketch option in Linear Pattern, you have to use a dimension in the direction of the pattern for the pattern direction.
              • Re: Linear Pattern Using 2 Guide Curves

                Matt - Thanks for your response and suggesting to use the Vary Sketch option.  It sounded like the perfect solution but it looks like this feature cannot handle the cross geometry as I am getting the following rebuild error: "A pattern with variant sketch option is not suitable for geometry pattern."  I would prefer to apply the linear pattern after I have extruded both legs of the angle iron; but tried it after just extruding the first leg and still get the same error.  Would you mind taking another look at my updated model (with all measurements in SKETCH_BRACING, LEG1 based off the tube geometry).  I'm either missing something or need to take another approach.  Thanks.

                  • Re: Linear Pattern Using 2 Guide Curves
                    Neil Larsen

                    A vary sketch requires you to merge the variable feature with the base feature for it to work.

                    That is in this case you would need to merge the bracing with the legs.

                    If you try to use bodies in the linear pattern with the vary option you get that warning - actually not a very insightful message in itself.

                    I made a small extrusion in direction 2 to get a proper intersection with the tubular leg body - else the ol' 'zero thickness geometry' condition arises.

                    actually you dont get a message about that it just fails to pattern otherwise..


                    You can get the bracing to pattern ok as you required using vary sketch but unfortunately I think there is actually a bug in it that will ruin your mission cos it only seems to pattern the 1st feature in the selection, unless I have overlooked something myself now. 09sp4 here.


                    EDIT: the only cases where selecting other features as well seems to work correctly is with chamfers and fillets?..and this seems to be the case back to at least SW2005..SPR time?...


                    The linear +cir pattern makes 1 body of the whole legs/bracing which is probably undesirable.

                    Personally I feel the whole thing is kind of messy done this way and I would have used weldments but...


                    I just did a rough version but preserving a similar L construction as you did for the example attach so you'll need to redo it sorry.

                    Notice that the sketch dimension I used in the direction is a slightly different arrangement...



                    Matt can feel free to tell me I've got it wrong..again


                    btw isn't it annoying to want to edit a feature and find you cant change to use say bodies in place of features because that option isn't shown in the FM anymore - you have to delete the whole thing and start again grrr....