Limicon Update - need "Equations" help 4

[Scopedog]

After finding out that I need a Logarithmic Spiral (or nautilus) instead of a Limacon, I did some research and found the equation I need. This was confirmed on Mathcad. Problem is I've never used the Equations command before. I need to be able to put in a number for variables "a" and "b". It will solve the rest.

r(t)= a*b^(s*t), where a and b are >0, and range t=.1 to 20

Look up "Logarithmic spirals" for ref. @ this site.

http://jwilson.coe.uga.edu/EMT668/EMT668.Folders.F97/Anderson/writeup11/writeup11.html

Thanks.

 

[rocheey]

SW doesnt allow variables in Equations yet. If you use a design table, you can use different cells to 'break up' complex equations into manageable parts. You can then even use Excels drop down menus as an 'interface' to your parametrics

 

[Scopedog]

So I can write an equation with numbers instead of variables and get an answer for r(t), but will it create the drawing effect I am looking for? I am sort of ignorant on the equations stuff. How would I write this equation? I am not finding much on the net on how to write an equation in SW. Thanks.

 

[CorBlimeyLimey]

SW Equations will not draw the "Logarithmic Spiral" for you. Equations are used to control aspects of geometry which the user has already drawn.

eg. Consider a simple cylinder ... Dimensions would be applied to the Diameter & Length ... if the Length is always to be 3xDia the Equation would be "Length@Extrude1"="Dia@Sketch1"*3 then when the Diameter is changed, the Length will automatically adjust.

In other words you will have to draw the "Log spiral" first & then use Equations to adjust your variables relative to known data.

from (the City of) Barrie, Ontario.

Support bacteria - they're the only culture some people have

 

[Arlin]

I think what rocheey and CBL are trying to say is:
You cannot PLOT an equation in SW to get a curve or surface.

There may be some 3rd party apps or macros that have this ability, but not SW itself.

 

[APPENG]

What I normally do in a situation like this is to create a VB application (macro)that writes the points based on a formula. You can either have it create points or a spline, or a curve through the points. Depending on how you want it to run. If you know the math for the task at hand, its pretty simple to get the rest.

Actually thee are two choices here...

1. have the macro control solidworks to create the curve while its calcualting the points.
2. write the VB app to create a text file of x y z points, then reas that file into solidworks by using the INSERT/CURVE/ "Through xyz points"

Either way you will get the curve you desire.



Regards,
Jon
jgbena@yahoo.com