【转帖】increasing length of part, want pattern instances to match

yang686526

increasing length of part, want pattern instances to match
i am developing a configurable body of a steel wagon body that my company manufactures.  it is similar to a big metal tub with a door on the back.
when i increase the length of the body, there is a rail alongside the body which increases to suit. the rail has slots cut into it in a linear pattern spaced at 300mm; the slots are in place so that we can easily locate a side panel.
the slots are spaced 150mm from either end of the rail. although this value is not imperative.
when i increase the length of the body, and therefore the length of the rail, i want the instances in the pattern to increase to suit the new length.
anyone have any reccomendation on how to do this?
i can not simply increase the space between the slots and keep the same number of instances, as this was my thought by using a sketch driven pattern.
first thought... may not be the best, but here goes.  you can control the number of instances of the pattern within the design table.  this could either be input manually or you could generate some sort of relationship between the length and number of slots.  this equation could be contained in the design table.
-dustin
professional engineer
certified solidworks professional
if you are using solidworks 2008 have a look at driveworks express.  the scenario you describe is exactly what the tool was intended for.
cole m
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to handle the pattern instances, use the area fill function.

slots 150mm from each end;
length between end slots varies;
slot pattern at 300mm;
therefore enter equation where:
# of slots (pattern instances) = length between end slots (a driven dimension you must enter) divided by your 300mm slot pattern distance.
the downside to this method is that you may not end up with even slot spacing at last position.
if you want to keep the spacing at 300mm and have the distance from the end vary, then try the following set of equations.
#slots = round((rail length 鈥?2 * 150)) / 300 + 1
distance from end = (rail length 鈥?300 * (#slots 鈥?1)) / 2
if you are using a design table (recommended), the #slots parameter and distance from end dimension can be added to the table and the equations entered into excel.  if you are not using a design table, you could have these as regular equations.
eric
sorry for resurrecting an old thread!
how can i control the number of slot instances with the equation?
the equations are fairly simple, but i don't know how to use the result of the equation as the number of slots.  i have tried simply typing the equation into the linear pattern instances option but it just comes up with an error saying:
"please enter a number between 0 and 1000"
i might be a doofus, and this might be a very simple thing to do...that's usually the problem :p

after you create the pattern, the number of instances becomes a dimension.  that dimension can then be controlled by an equation.   
-handleman, cswp (the new, easy test)
there are several different ways to do it.  i recommend reading up on: equations, configurations and design tables in the solidworks help files.  hopefully the following with get you jump started on one or the other of two approaches.
the first is with an equation.  go to tools -> equations, click on add.  this will bring up a little equation entering window.  the trick is figuring out the name of the variables that you wish to include in the equation.  with the add equation box up, click on the pattern feature to get its dimensions to show, and then click on the instance number.  this should put that dimension / variable into the equation.  you then just repeat the process for the other dimensions in your equation.
the second is through configurations and a design table.  make two configurations of your part, and have all of the dimensions that you wish to control different in the two configurations.  then use insert -> design table to create an excel spreadsheet which controls the dimensions.  let it auto create the design table.  you can then enter the equations into the appropriate cell of the design table.
eric

sorry, but i'm probably a doofus too.
i think the original question was - can you, and if so how do you, use the equation you've created to control the number of instances into the linear pattern property manager?
i know you can accomplish this with a fill pattern, and i understand that a design table can also be used (though i've been to lazy to go down that road thus far), but the simple and obvious solution seems to be to create a formula and use it in the property manager. alas this seems to be impossible.
you can't put equations in the property manager.  you can't "use an equation you've created" to control anything.  the thing you want to control has to be the left side of the equation.  you can only apply an equation to any parameter of a model after that parameter has been created.  if you want to control pattern instances, double-click on the pattern in the feature tree.  do not edit the feature.  somewhere on screen two dimensions will appear.  one of them is the spacing.  the other one is the number of instances.  now go to the equation editor.  create a new equation.  for the left side, click on the dimension that pops up with the number of instances.  for the right side, click on dimensions, do math, whatever.  that's how equations work.
-handleman, cswp (the new, easy test)