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| Figure 1 - Trapezium to Circle transformer {3D export from the STOR21beta software} |
Several users have requested a trapezium to circle transformer as shown in figure 1. Rather than release a version that can only make a trapezium to a circle, it's now possible to define the quadrilateral corners as shown in figure 2. There are 3 main types of quadrilateral: convex (A to F),concave (G) and crossed (H) as shown in figure xx. Concave and crossed are not applicable to sheet metal , or at least not a common development.
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| Figure 2 - Types of quadrilateral: A)Square, B)Rectangle, C) Isosceles Trapezium, D) Trapezium ,E)Rhombus, F)Parallelogram, G)Concave, and H) Bow tie. |
STOR20 used R1 to R4 to define corner radii but this is now changed to RA,RB,RC and RD and these can be defined even when the quadrilateral is not rectangular.
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| Figure 3 - Corner radii |
From figure 3, the corner co-ordinates are measured from 0,0 and their respective sign is required. When the corners have a radius applied then the co-ordinates are the intersection of the 4 main sides where from figure 3 you can see the corner angle is divided equally between the tangents of the 2 adjacent sides. Some draughtsmen issue drawings with dims to the centre of the radii - you'll have to work out or use CAD to then find the corner intersection points. Note, each corner radius to be independently specified, as shown in figure 4.
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| Figure 4 - Independent coner radii |
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| Figure 5 - STOR21 beta screen shot defining the quadrilaterl corner co-ordinates. |
To enter the quadrilateral corners slide the properties pane over to the left (or click the trapezium tool bar button) where you can see 8 edit boxes for the corners. The corners are defined on the z plane.
I feel that entering 4 corners by co-ordinates is less intuitive than just entering the 2 rectangular dimensions therefore I've made the interface offer both options. Simply tick the square coordinates check box and the rectangular dimensions SX and SY become non-editable. You can now control each of the 4 corner vertices by entering x,y (on the z plane). Remember the offset OX,OY,OZ refers to the circle end and is measured from 0,0,0.
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