The Curve Driven Pattern
is a powerful feature in parts, and now in SOLIDWORKS 2014
, assemblies. It allows you to repeat and array features, bodies or parts along a 2D or 3D curve direction, maintaining equal spacing as you go. It is in fact a great alternative to a linear pattern if you use a straight line as the reference sketch- this is the only way to achieve an equal spacing scenario. There is an Enhancement Request to allow equal spacing in a typical linear pattern.
Anyway back to the main focus of this blog, and what I wanted to discuss is how to better control patterns along more complex 3D curves- in this example I use a Helix. The starting point was to draw a helix and the seed feature- I then wanted to pattern the nut so that it followed the helix as if it were linked or welded to a chain that passed through.
The problem is the preview the Curve Driven Pattern gives only previews using the "Align to Seed" option therefore all additional instances are parallel to the seed feature, not what I wanted.
So how do we get the previews to be perpendicular to the curve?
Well the key to this is the option "Tangent to Curve" available in the Property Manager. However when a 3D sketch/ curve is used for the pattern direction an additional item must be selected to get the pattern to work - this is an option under the heading "Face Normal"- this is defined in the SOLIDWORKS Help as follows:
So we need a face that the curve lies on to set the "Normal" direction.
In this case no such face exists, so instead we can model a surface with a simple extrude to get a face on screen- this surface can be subsequently hidden or deleted. The circle used to drive this surface extrude is the same DIA as the helix ensuring that the helix lies on that resulting face.
Then with this selected in the Face Normal box, the preview looks a lot more like it:
So with a bit of extra work you should be able to get the result you need.
By Adam Hartles