Equation woes

[J-C]

Situation:
I have a part that is modeled in-context of an assembly. Basically a C-Channel. Its extruded depth is linked to a "layout sketch" in the c channel part file. The layout sketch is linked in-context to a sketch in the assy.

Problem:
I need a pattern of holes, equally spaced along the c-channel. This is created with a linear pattern as the number of holes could change as the overall length of the channel grows. I don't have an extruded depth dimension to use in the equation. So I put a ref dimension in the layout sketch (first feature in the tree). Then I can use it to drive hole spacing in the equation. Problem is it takes 2 rebuilds for it to update. In the assembly it won't update the pattern at all, just the length of the part. Not sure why this is

Bug, limitation, ER ????

Jason

SolidWorks 2007 SP3.1 on WinXP SP2

 

[handleman]

Have you tried driving the pattern with an equation defined from a dimension (reference or other) in the context of the assembly layout sketch? For example:

"D1@LPattern1"=("D1@Sketch1@Assem1.Assembly")/"D1@Sketch3"

 

[CorBlimeyLimey]

Another solution would be to use the Fill Pattern option. The extents of the fill area can be constrained to the length of the part so that a change in length affects the fill area accordingly.

 

[J-C]

This seems to occur even if not in-context. I've linked the file below. The length in this case is a driven dimension in the first sketch. I use it to create the equation in the pattern spacing. Change the dimension between the two points in the first feature which changes the driven overall length. The hole pattern won't update til you rebuild twice. Not sure why this shouldn't work, the length is calculated before it gets to the hole pattern.

http://www.mooload.com/new/file.php?file=/data/110607/1181589870/Hole+Spacing.SLDPRT

Fill Pattern won't work as it doesn't have enough control.

Ultimately I need it to calculate an "if/then" type statement in the equation. As the spacing grows, holes get added such that the spacing never gets larger than a certain amount.

Jason

SolidWorks 2007 SP3.1 on WinXP SP2

 

[dmctiernan]

Hi Gildashard,
I often have a similar situation as I model a c-shaped sheetmetal components with have a series of profile cutouts and bolt holes whose qty and spacing are dependant on the overall length of the component.

The solution that I use is to use two sketches to drive the feature. One sketch is the cross-section of the component and the second is a line which runs in the direction of the extrude. I then create the extrude, however instead of extruding to a particular depth or to a plane that has been defined in context of the assembly, I simply extrude up to vertex, the vertex being the end point of the line in the second sketch. This line should be in context to your assembly. In order to get the equations to work, simply edit the second sketch, the one with the line, and add a driven dimension to the line. You now have the dimension that need.

I hope this helps, let us know how you get on.