Advanced Modeling
By D Cheshire Page 1 of 7
When modeling any part you are likely to be working to certain parameters
which can be used to create construction geometry in your model. In the
case of this remote control unit let’s assume that the design specification
states the part should be no longer than 150. Now let’s use that
information to define two datum planes. Choose INSERT > MODEL
DATUM > PLANE and click on the RIGHT datum in the graphics window.
The Offset option is set automatically in the dialog box so type in a value
of 150. In the Properties tab type a name of ENDLINE and click OK.
Repeat this making a similar datum called MIDLINE at a distance of 75.
That has set up the reference geometry for us to use.
We are now going to design the outside shape of the remote. As you can
see from the picture this is a complex shape and the simple EXTRUDE
and REVOLVE commands would be totally inadequate. We are going to
use a command w e have already introduced VARIABLE SECTION
SWEEP but use it to its full capabilities.
Sketching with Splines
You may remember this command relies on existing curves so we need to
draw some curves now. Like many complex shapes, lines and arcs aren’t
suitable for the shapes we want – we will use a free form curve known as
a spline.
Choose INSERT > MODEL DATUM > SKETCH and choose FRONT as
the sketch plane. On entering sketch mode click on the ENDLINE datum
as an additional datum. The is used to create splines. Choose it now
and have a practice – it takes a little getting used to. Each click of the
mouse defines a point on the curve and ProEngineer smoothly interpolates
between these points. Click the mouse button to finish drawing a spline.
You can then use the selection tool to edit the curve by dragging any
of the control points.
Figure 1 : First control Spline
Once you have got the hang of drawing with splines draw the curve shown
in Figure 1. Note it has 5 control points and the first and last points lie on
the references and are horizontally inline. Exit sketcher.
Repeat the previous command and draw a second, separate curve. This
one is just a simple horizontal line aligned to all references as shown in
Figure 2.
Figure 2 : Second Control Curve - Straight Line
These first two curves define t he shape of the remote when viewed from
the front. Now we will draw two curves to control the shape when viewed
from above. Draw another datum curve using the TOP datum as the
sketch plane aligning the ends of the curve as shown in Figure 3.
Figure 3 : First Top Spline
The fourth and final curve is identical to the last one so simply click on the
last curve in the browser window then choose EDIT > MIRROR and pick
the FRONT datum as the mirror plane. You should now have 4 curves and
are ready to create the solid.
Figure 4 : Four Curves Defined
