2d polar coordinate equation sketch techniques

[rjwoods77]

Hello everyone,

I need to model a stoffel spline (

http://stoffelpolygon.com/)

in order to get the geometry to a cnc grinding machine in the form of a dwg file. I would love to be able to model this correctly in solidworks but if there is a quick cut to a dwg file then I will take that as well. What I need to able to do is model a polynomial equation in a 2d space that is reliant on angle to give the x and y value. I need this to be a complete solid polynomial line and not a collection of finite points with line in between. I would also like to be able to utilize whatever help you guys maybe to model an involute spline. I would appreciate any help you guys might be with this. I got this company to sponsor the free grinding but I have a narrow window for this offer and am looking to get it done as soon as possible. I included the .pdf with all the info. I am looking to do this with a 4 lobe .75 inch spline.

Thank you,

Rob Woods

 

[AnnaWood]

Use Excel to generate your x/y coordinates from the equations in the reference pdf, then save as a coordinate file that you can bring into SW and create your spline with a curves through XYZ points.

Search on 'curves, through XYZ points' in SW Help.

Cheers,

Anna Wood
SW2008 SP1.1, Windows Vista
IBM ThinkPad T61p, T7800, FX570M, 4 gigs of RAM

http://designsmarter.typepad.com/solidmuse

http://www.phxswug.com

 

[rjwoods77]

Anna,

Is there any way to import the data as a complete line and not a set of finite points that I try and fit a line to. I guess I could do it on an large number of degree increments but I am concerned that the SW line fit will not be a continuous equation line and a number of finite straight lines. CNC machines are notorious for picking up the smallest "errors".

Rob Woods

 

[rjwoods77]

I have never written a macro much less looked at one but I found these for Pro-E for involute curves which I would imagine could be translated for the polygon splines. Is looking into making a macro a possible solution or should I not waste my time looking into it.

http://www.cadquest.com/books/pdf/gears.pdf

http://www.profilesmagazine.com/p33/marsalek.html

 

[TheTick]

The "hard way":

By hand, calculate a set of coordinates for a set of points. Sketch the points. Sketch a spline on top of the points.

I recommend having the points in one sketch and the spline in a subsequent sketch. That way you keep your points if your spline flakes out on you.

 

[SBaugh]

Anna is right - You can import XYZ coordinates from Excel into SW that will create a composite curves. You can use that curve for many things then. It will not create points in the system only a curve. Please look at the help on this.

As for macros, why would you need one if its all right there in SW now?

If you are wanting to make gears, then you can look at Geartraxx. I used this before and it works GREAT!

Regards,

Scott Baugh, CSWP

http://www.scottjbaugh.com

"If it's not broke, Don't fix it!"

faq731-376

 

[takedownca]

I see this question coming up more and more frequently. I don't know why SW won't implement equation based curves already. In the meantime, this macro will automate the creation of equation based curves, including those using polar (cylindrical) coordinates.

 

[gatz]

Been following this topic for a while and have done a little experimenting with *.txt files generated by Excel (and modified for ONLY x,y,z values).

The Insert-Curve-Curve Through xyz points works fine, but how can I make this work for only the Points and NOT the curve itself? Or is there someway to "desolve" the Curve to its xyz Points?

I'd like to be able to use Excel to generate data, then construct a 3-D sketch in a SW part for those Points.

Thanks.....you guys have been a big help for a novice.

Gatz

 

[gatz]

oops, maybe I got this in the wrong thread.
This was meant to be about the 3-D curves.

gatz

 

[takedownca]

Check the macro link above. It has an option to import the curve as a 3D sketch instead of a curve.

 

[rjwoods77]

Thanks everyone for the suggestions. I will try them out and see what happens when I get home. The only reason I am skeptical of a points based vs equation based line is I am worried the spline wont work correctly. Its like busting up an involute into steps and i know that gear cutters work on equations and not steps.

Takedownca,

Thank you and I will see whats up with that program.

Sbaugh,

I wasnt aware Geartraxx was free. If it isnt then that is why I am interested in doing my own deal.

 

[MadMango]

Geartrax (

http://www.camnetics.com/GearTrax.htm)

is not free, but for $750USD it more than pays for itself if you are doing a lot of work with gears or gear trains.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[TheTick]

All of the possible native SW approaches are based on points & interpolation. There is no such animal as an equation-based curve in SW. Additionally, SW has no means to control the degree of a B-spline.

The best you can do is generate the curve w/ some points based method, then check the resultant spline for deviation from the ideal. If you are careful to control spline curvature, you could probably get within a reasonable tolerance with very few defining points. A macro to check results would not be difficult to write.

 

[gatz]

takedownca,

Is VB required to run the funcplot.swp ?

I placed the extracted file in (a new) SW/Micros folder and assigned a HotKey to it.
Opened a new Part and when I hit the HotKey, nothing happens, and if use Tools-Macros>Run, browse to that same file and click on it to open, nothing happens either.

Or is the Macros folder in the wrong place?

gatz

 

[takedownca]

gatz,

The only requirement, other than having SolidWorks installed, is you must have Excel. Also, I have only tested the macro in SW2007.

 

[gatz]

I have Excel & SW2006
Re-read the Help topic about the "Macros" folder.
It mentions putting the folder in the Solidworks installation directory (in the same folder as sldworks.exe)
So, I placed it under the main Solidworks folder (C:\Programs\Solidworks\ .....where the SW application icon shows up on my computer) Is this the same as "installation" directory and is it correct?
OR....
I see a folder called sw2006-0.0-4.1-i that has the language settings, some other sw-related files and a file called WindowsInstaller-KB893803-v2-x86
Is that the place they're talking about?

What should show up on the screen of a Part document when invoking the funcplot.swp ?

Does the related Excel or *.txt file need to be opened 1st ?

 

[takedownca]

gatz,

If you have Excel installed, the only thing you should have to do is select Tools>Macro>Run, find the SWP file, and click OK. I've attached a picture of the GUI that should come up. If it's not working, try selecting Tools>Macro>Edit and opening the macro in the VBA editor. At that point you can run the macro and debug where it stops prematurely. I don't have 2006 installed so I can't help much.

 

[CorBlimeyLimey]

The folder called sw2006-0.0-4.1-i looks like the update files. Nothing should be added to it.

The default SW install folder is C:\Program Files\SolidWorks, but the best place for any custom files is almost anywhere except in the SW installation folder. If SW is updated, or the install folder becomes corrupted, my custom files remain safe.

In my Shared Docs folder, I created a Custom SWXXXX folder (where the XXXX is the version), and inside that I have matching folders for each category in the Tools > Options > System Options > File Locations section. The File Locations is then pointed to each folder.