Parametric Problem: Circular patterns

Question

Parametric Problem: Circular patterns

Gaz (Automotive)

(OP)

16 Mar 01 19:32

As a student of SW I have a problem that I need help with.

I have seen some great advice in here, but some people don’t explain their problems well enough to advise on, so here goes mine.
The problem is with circular patterns and parametrics.
Imagine a rectangular plate with 3 or 4 holes in it (taking up most of the plate), arranged by a circular pattern at a small degree of rotation (say 20 deg), I need the plate to change size as the number of holes and angle of holes change.
Is there any way of linking the plate dimensions to the circular pattern definitions? Or can anyone think of a work around?
Also can an equation be linked to the circular pattern parameter box?

Thanks for your help
Gary

dwilson (Mechanical) · Answer 1 · 2001-03-19 08:14:31

Gary,
I think I understand your problem and I have a solution. If you dimension the hole you use to pattern with a radial distance from the origin and an angular dimension, you can use 4 equations to define your relationships.

definitions:
W = width of rectangle
R = Radius from origin to center of hole defining pattern
A = Angle from horizantal to hole defining pattern
a = Angle defined in pattern
I = number of instances
d1 = W
d3 = Height of rectangle

1) A = (180-(I-1)*a)/2 ONLY VALID WHEN a*I < 180
2) W = I*R*sin(A)

Center rectangle about origin
3) d2 = d1/2
4) d4 = d3/2

If you have questions or would like to see a simple example model, let me know.

Gaz (Automotive) · Answer 2 · 2001-03-20 06:20:10

Thanks D

I'll play with this and see how I go.

Gary

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Parametric Problem: Circular patterns