Acorn User


Computer Aided Design And Manufacture I: Intersecting Cylinders

Categories: Review: Software
Author: Chris Steele
Publisher: Microelectronics Educational Development Centre
Machine: BBC Model B

 
Published in Acorn User #032

Computer Aided Design And Manufacture I: Intersecting Cylinders

The rather grand title of this software somewhat hides the fact that it is concerned only with the solid geometry of two intersecting cylinders.

The programs auto-run from disc. Once the diameters of the two cylinders and the angle at which they intersect have been entered, the program generates a wireframe side-on view. The object can now be rotated about X, Y and Z axes by pressing a function key followed by the amount of rotation required. A zoom feature allows the image to be inspected in detail, and a further function key allows the image to be reset to its original aspect.

Once you've obtained your desired view, function key 7 will produce a surface model with the two cylinders appearing to be solid, but I found this difficult to see on a monochrome monitor.

Finally, and perhaps most usefully, developments of the two cylinders can be drawn on the screen. The documentation suggests that these can be traced from the screen onto paper, allowing a model to be built, but the author admits this is not easy and is prone to inaccuracy.

The documentation includes an A5 booklet and three A4 sheets. The booklet is adequate, describing all the functions of the software and including appendices on the solid geometry theory and equations used in the package. The extra sheets include a function key overlay and sample developments.

The introductory information on the packaging claims that, "This package gives an introduction to computer aided design and manufacture. It illustrates how a computer can take over much of the routine of design; how computer graphics can be used to see what an object looks like before it's made; and how the design data held in a computer can be used for manufacture." This is quite true, but I know from painful experience just the sort of questions a group of perceptive and cynical students would ask: "What about three cylinders?"; "What if I want octagonal pipes?"; "Can it analyse flow turbulence?"; and, the most common one, "Can we play Invaders afterwards please?"

What MEDC are attempting to do with this package is laudable. However, students tend to be critical unless it can be demonstrated that this type of computer aid would be directly useful to them. If this package were introduced halfway through a project involving intersecting cylinders, after the students had already attempted to produce the developments themselves by hand; and if a plotter or printer were used to draw the developments, I don't think the students would need to be told how useful CAD can be. As always, it's the application and integration of the software that is of prime importance.

Chris Steele