This tool is now also available as a fully automated macro for v7 and v8 users. The macro is the much-preferred tool as it eliminates the need for CurveLab and automates the extrusion and trimming steps. This tool will remain here for the benefit of v6 users, as the macro will not run on v6.
System requirements: for CurveLab to operate properly it is necessary that Internet Explorer version 5.0 or later with VBScript be installed.
To install CurveLab you need to know the location of the TurboCAD main program. If you are not sure where it is, find it with Windows Explorer and make a note of its location.
Run the installation program. When the dialog box appears, ignore the directory shown in the dialog window and click the "Browse" button.
Using the controls in the dialog box and find the TurboCAD executable ("TCWn0.exe"). ("n" will be your version of TurboCAD).
When you find it, double-click the file name and you will be returned to the original dialog box.
Make sure that "HTML plug-ins" is checked and click the "Ok" button.
CurveLab is now installed. Note: if you are running more than one version of TurboCAD you will have to repeat the above for each version that you want to run CurveLab in.
Click on the little "Down Arrow" just to the right of the "Tc" icon and select "CurveLab".
Go here to view Lotus ScreenCam movies of CurveLab in action. Note: If at anytime you go to another page on the Internet Palette, CurveLab will stop and the script in the script window will be lost.
The author strongly recommends that the user read the notes at the end of these instructions before proceeding.
Creating the compression spring is a three-step process: creating the extrusion path, extruding the coil, and trimming the ends to final dimension. If you follow the flowing systematic instructions, you should be able to create a spring to your specifications. The spring will be located perpendicular to the User Coordinate System and with the base of the spring located relative to the User Coordinate System 0, 0, 0.
Creating the extrusion path
To create the extrusion path, do the following:
Switch to one of the ISO views.
Using the "Line" tool draw a single line of any length somewhere on your drawing.
Select the line you just drew.
Start CurveLab and click somewhere in the script window.
Turn on the 3D option (Ctrl+d) and Cartesian option (Ctrl+r).
Clear the script window (Ctrl+a followed by Delete).
Download and copy the script paste it into the script window.
Scroll to the top of the script window and edit the values that describe the spring.
Coils:
The number of coils in the spring. This value must be greater than zero. It does not need to be an integer.
SegmentsPerCoil:
The default value is 30. Adjust this for appearance and file size. Smaller values will save on file size at the expense of drawing quality.
Sign:
This value determines the direction the spring is wound. If the value is 0 or positive, the spring is wound clockwise from the top. If negative, it is wound counter-clockwise.
WireOD:
The diameter of the wire that the spring is wound with.
SpringOD:
The outside diameter of the spring. (The script will adjust for WireOD).
InstalledHeight:
The finished height of the spring after trimming.
FreeHeight
The height of the spring when unloaded (free standing)
X0, Y0, and Z0:
The location of the center of the bottom of the spring relative to User Coordinate System 0, 0, 0.
Click in the script window and push the F8 function key.
The extrusion path should appear at location X0, Y0, Z0 on your drawing. If you made a mistake or do not like the result, leave the extrusion path selected, update the values, and push the F8 function key again.
Extruding the coil
Draw a circle the same diameter as WireOD.
Setup the "Normal Extrude" tool with the following Properties:
3D— Surface
Extrude Shape—Smooth
Extrude the circle using the "Select Extrusion Path" option using the path you just created in step 1.
If you are running v7.1, also use the "Select Extrusion Basepoint" option using the center of the circle as the extrusion base point.
Trimming the ends to final dimension
Switch to a view perpendicular to the spring's axis.
Set the work plane to "Plane by Active View".
Using the "3D Slice" tool and the "Slice by Line" option, slice the bottom of the extrusion with a line perpendicular to the spring's axis through Z0.
Repeat through Z0 + InstalledHeight.
Delete the sliced-off portions of the extrusion at the top and bottom.
The script does some error checking. It constrains the value of InstalledHeight to a minimum value consistent with the values of WireOD and Coils. It also constrains FreeHeight to be at least as large as InstalledHeight.
If during step 1 you get an error message or get something unexpected you have probably inadvertently changed the structure of the script. If you cannot find the problem, reload the script.
Occasionally, CurveLab will refuse to update the selection. If this happens, delete the selection and draw a new line. Do not forget to select it before returning to CurveLab.
You may have problems with the slicing operation in step 3. This can happen if the wire diameter is large relative to the spring diameter. Generally, this can be cured by re-extruding with a wire diameter slightly smaller than WireOD. A 0.1% reduction should be more than sufficient.
You can extrude as a solid but appearance will suffer, the extrusion and slicing operations will take longer to perform, and the slicing operation will probably create some ugly artifacts.
Springs generated with FreeHeight equal to InstalledHeight will appear uncompressed. Variable rate compression springs close the space between the coils on the ends of the spring first. If you want to show the spring in a partially compressed state, increase the value of FreeHeight or reduce the value of InstalledHeight. To show a fully compressed spring set InstalledHeight = 0. The error checking routine will set InstalledHeight to the minimum value consistent with Coils and WireOD.
This update corrects a calculation to improve the appearance of the spring when compressed. This update also changes the note about fully compressed springs.
3/11/03
Removed the script from this page and replaced it with a download
Added the link for the scripting-errors fix
Corrected the extrusion instruction for v7.1
Removed support for v6.5
