Page updated: 2006/08/17
'stcad8 was created on 2003/07/01.
patch83.zip supersedes all patch8*.zip.
'StCAD' allows users to create and manipulate assemblies, which are collections of 3D parts. The parts are 3D solids, which can be connected by joints, constraints, contacts, actuators, springs, dampers or forces. The parts and connections define the structure or mechanism that the assembly is meant to represent. Animation is possible, if the user can provide time series of position and orientation data for the parts.
Users can also obtain output data in the form of plots and tables. XY plots can be zoomed and set to equal scales. Data series available include linear and angular displacements, velocities, accelerations and other user generated data.
'StCAD' has been used to create a freeware
called 'freeCAD' which is
a 3D CAD with Motion Simulation. The parcel 'StMbD' has been included
provide a functional demonstration, but its source code is hidden. For
more information visit:
Users need to provide the domain to
simulate the behavior of the
system. Simulation progress can be animated and stopped any time. After
simulation, the computed solution can be used for animation or frame by
frame analysis. Full 3D pan, zoom, tilt and rotate is available
during simulation and animation. Users can also obtain output data in
the form of plots and tables. XY plots can be zoomed and set to equal
scales. Individual parts can be saved into files and reinserted into
any assembly repeatedly. Assemblies can be saved in binary or tab
delimited text format with textual notes and simulation data for later
reload. The text format allows pre and post processing of
assemblies by other programs, especially spreadsheet programs. Other
specific text formats are for MOSES, PDMS Review and POV-Ray. 'StCAD'
runs on Windows, Macintosh PPC, Linux PC and other Unix's. Assembly
are unchanged across platforms.
To try 'StCAD' in VisualWorks 7.x:
Install the VisualWorks enviroment first.
Create a directory, say, C:\vw7xnc\stcad8 for the downloads.
Download stcad8.zip (2,287,168 bytes).
Download patch83.zip (8,817 bytes).
The files should be good on all platforms supported by VisualWorks.
Unzip stcad8.zip into the same directory.
Unzip patch8*.zip into the same directory. Let it overwrite other files.
Save a new image in the directory and launch it from you operating system.
Load parcel C:\vw7xnc\stcad8\stcadstart8.pcl.
Click 'Yes to All' for all prompts.
Launch 'freeCAD' with doit 'StCAD.Editor open', if it is not already launched.
Inside 'freeCAD', click Explain/Quick Test/ and Explain/Quick Start/, to find instructions and tutorials.
Quick test 'freeCAD':
Make sure that the example assemblies (*.asm) are in the directory of the image.
Click File/Open/Assembly/ to get list of example assemblies.
Choose one, say, fourbar.asm
Click View/Tilt Rotate/ to center the model. Drag the handles to tilt and rotate the 3D assembly.
Click Simulation/Animation/ to get the animation dialog. Click Play to start animation.
You can click any View menu item and drag handles, even during animation.
Please report any problems to
Click Explain/Quick Start/ to learn how to build a model from scratch. Together, the tutorials demonstrate the available features in 'freeCAD'.
Inside 'freeCAD', documentation are collected in a series of menu items labeled 'Explain'. Click on them anytime. But you MUST run the tutorials to learn 'freeCAD'. Click Explain/Quick Start/ for a list of examples on projectiles, circular motion, relative motion, pendulums, spring-masses, four bar linkages, piston crank, gyro, cam follower.
The motion simulation theory is in the
Koh, A-S., and Park, J-P. "Object Oriented Dynamics Simulator," Computational Mechanics, Jun 1994, 14(3) 277–287.
Right clicking on some mice does not bring up the correct menu. Try right clicking while holding the ctrl key down.
On Windows 98, the help dialog for motion and force-torque dialogs will not close when the X button is clicked. Close with ESC key.
On machines with low memory, desktop icons may become white when 'freeCAD' exits. Reboot to recover. Internet Explorer 5.5 seems to be the cause. Upgrade to Internet Explorer 6.
If resizing the window is very slow to repaint, disable 'Show window contents while dragging' found in Start/Settings/Control Panel/Display/Effects.
'Out of Memory' error at startup. The probable cause is having too many fonts. Execute with the following command to start freeCAD
./visual -h10M visualnc.im
Animation is jerky when the graphics window is very large. Reduce the window size.
Please report problems to
To pose a question, submit it to the newsgroup comp.lang.smalltalk. Prefix the question with [StCAD] to distinguish it from other questions in the newsgroup.
Finally, you can email:
For more information, please contact A-S
Koh at firstname.lastname@example.org
Copyright (C) 2000-2003, A-S Koh, All