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Pro/Engineer   January 2005   Tip-of-the-Month

## Patterns to Follow a Curve

To make a pattern that follows a curve, here are a few quick steps and tips.  The pattern of Figure 1 was created on a curve, and designed to follow it.

 Figure 1.  Features  on a Curve
The steps for creation are as follows:

(Instructions are given for Pro/E 2001.  I do not recommend Wildfire or Wildfire 2 as they are less efficient and have many problems.)

1.  Create the curve.  This can be any continuous curve, but must be a curve feature.  In versions of Pro/E including 2001 and earlier, curve types are easy to find:  Insert > Datum > Curve... > (choose from a number of curve creation possibilities).  In Wildfire and above, PTC scattered the curve types all over in different menus:  (which I have to say was really stupid),  Some are in  Insert > Datum > Curve,  some are in the  Edit  pull-down menu -- like  Project . . .

2.  Create a point on the curve:  Insert > Datum > Point > On Curve > Length Ratio  Pick the section of the curve you wish to use, or the whole curve by using Query Select.  Notice the section of the curve that highlights -- the curve section typically highlights first, then the whole curve next.  Depending on which end of the curve you wish to start your pattern, the ratio number may be near 1 or near 0.  (See Help on Points for more info.)

3.  Create the point pattern.  Create a Dim Pattern using the point ratio parameter, and make the increment be a fraction so the sum of the ratio steps remains less than 1 (greater than 0 if the step is going smaller).

 Figure 2.  Pattern  of Points
TIP:  Make the pattern now to be sure it will pattern as you wish, then create the rest of the features using the first point as the reference.  Later you can choose how to create the patterns.)

TIP:  Typically it is a good idea to write the ratio and steps into a relation so it is controlled by the number of pattern members.  You change the number of members, and let Pro/E calculate the ratio step.

4.  Create an Axis through the first point, Tangent to the curve.  Insert > Datum > Axis > Tan Curve.  Select the curve (the same portion of the curve selected when the point was created), then choose the point for location.  (There was one version or date build of Pro/E where this functionality was removed.  It may be Wildfire, I do not remember, but they took out the ability to create an axis tangent to a curve through a point on the curve.)

5.  (Optional, depending on geometry)  Create a Datum Plane Through the point, Perpendicular to the Axis.

TIP:  Make sure all references selected during feature creation will be valid for every feature instance along the curve.  If a reference is not part of what will be patterned, make sure it will be valid for all instances of the pattern.  A Sketcher Reference plane for instance.

6.  Create the feature(s) to pattern.  In this example, a Protrusion was revolved about the axis, then some Cuts were revolved and extruded.

7.  Pattern the features.  There are 2 main ways to pattern the features, and the method you choose can depend on your preferences, how the features were created, references, or on a Pro/E whim.  I almost always try to create a Ref Pattern of each successive feature – First a Dim Pattern of the point (as above), then a Ref Pattern of the Axis, then a Ref Pattern of the Datum Plane, etc..  If the features will not Ref Pattern, or if you prefer, Group the respective features, then Pattern the Group.  (See Help documentation on Groups and Group Patterns for more information.)

 Figure 4.  Features Pattern on a 3D Curve

FINAL TIP:  Read the Help documentation for assistance with any of the above features or creation techniques.

Good luck with all your Pro/E creations!
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