Conch shell in Creo Parametric

You can use Creo View Express to view this file (conche.prt.2😞 http://www.ptc.com/products/creo/view/express/

Thank you all for you interest and pointers.  I now need to work out how to create the curve for the sweep path using a trajpar function.  If someone with more mathematical acumen than I can lay out the formula for me I would be most grateful.  I think I can work out the relations to set the section to vary.

Regards John E Forth

John,

You started quite a buzz internally here at PTC. Check out this blog, http://blogs.ptc.com/2011/12/01/the-fibonacci-conch/

Those Mathcad guys are always showing off. I think we can do this in basic Creo... maybe with a datum graph. Trajpar is a wonderful thing but it's also not necessary all the time... there are other ways to create interesting helicals and strange sweeps without it.

Hmm... finally something fun to play with!

Hi Mark...

Can you upload this as a zip. Clicking the link opens the file itself rather than allowing a download. Maybe I should try IE instead of Mozilla.

Brian,

You should be able to right-click on the link and select Save Target As from the pop-up menu to save the part (rather than open it). If not, let me know and I'll email it to you.

Looking forward to seeing what you come up with!

Cheers,

Adam

Hello John

I try to create Fibonacci Spiral through Golden Rectangle with creo Parametric.

Here is some examples of my 3D model "Fibonacci Spiral" (I use some sketch and variable section sweep with Trajpar functions)

If that's what you need, I can make a short video demonstration. Let me know

Golden Rectangle and Fibonacci Spiral

3D Fibonacci Spiral

3D model of Fibonacci Spiral

Best Regards
Vladimir

Here it is, just in case

http://apps.ptc.com/schools/conche.zip

Thanks Adam.. got it.

While I think Vladimir is on the right track, if you go back to John's original post, he's trying to use the Variable Pitch feature of a Helical Sweep to accomplish the shape. This makes use of an internal datum graph. The problem here is that you don't really have much control over the graph.

If one were to create a Datum Graph as a standalone feature, there are more options available (such as relations) which could help define the shape of the graph. With the pitch graph inside the Helical Sweep feature, you're limited to simply plotting points along your profile sketch. This is where John is getting stuck.

I can make a standalone datum graph... and I think I can use equations to develop a fibonacci curve for the pitch. This doesn't need to be a 3D spiral curve... it just needs to represent the ever-increasing rate of pitch... sounds like a parabolic curve to me (like the shape of the graph of y = x^2 only with fibonacci values). The problem comes in that I cannot use my standlone graph in place of the pitch graph Creo wants me to use. I think this is exactly what John is saying.

The obvious answer is what Vladimir did... he skipped the Helical Sweep feature altogether and went directly for a Variable Section Sweep.  This was a logical approach... but I'm still not convinced it's the only way.

I'll keep tinkering... anyone else have any ideas?

My life what have I started!  I just hope I can do your efforts justice.  However a word of caution here.  This may well be an interesting mathematical exercise but the reason for it is to produce a shape that can be used as an electric kettle.  Therefore it has to be made to, literally, hold water.  So far we have been able to create a solid and a surface model of a spiral but neither can be, respectively  shelled or thickened. The reason is that the spiral is by nature a self-intersecting solid.  The real 'engineering' trick is to create the conch and then turn it into an injection moulded reality.  Now that really is the challenge. 

Regards

John E Forth