Another ULTIMATE CHALLENGE

hey all-
I had an idea when looking at the other ultimate challenge thread.

Here’s the challenge: make a mobius strip in inventor. Preferably rounded, But whatever you end up making will be fine.

So have at it! I’ll post later if I end up succeeding!

Ouch!

I’ve done it in Pro/Engineer, but I imagine it would be much tougher in Inventor.

No way man! I’m on vacation right now, and as soon as i get back home ill do one in inventor to show you. On the ultimate challenege thread I’ve already done one, but it wasnt with a circle. In the mean time I’ll think about how to do it…

Ok on an edit of this post, this is how ill probably do it: Make a really large twist, and then using the replace face or even cut command to subtract extra material from it, making it arced and twisted at the same time. meanwhile, usee the rotation to bring the rest of it through the rest of the circle making it a complete loop.

hmmmmm. i wounder where he got that idea…

ahahahah. thats my post from the first thread.

i think a harder task is a triangular mobia prism. Like a mobia strip but with a triangluar prisim instead of a sheet of paper.

But that wouldn’t really be quite the same, would it? You’d have to twist it by some multiple of 120 degrees, instead of 180 as in the normal Möbius strip…of course, it would still be really cool, as you’d have to go around three times instead of twice to get back to your starting point.

It was kind of easy in Pro/E.

http://www.chiefdelphi.com/media/img/dee/deedae4c5850366d4ea0e997d781f6fd_s.jpg](http://www.chiefdelphi.com/media/photos/24592?)

How’s this?

Andy B.

ok, so how did you do it? and in what system cause that looks pretty well done. Both of you.

I used Pro/E Wildfire 2.0. It’s a Swept Blend (two actually - one for the half with the twist, and another to complete the loop).

I’d walk you through it, but if you have access to Pro/E, you’re better off using their Feature Creation guide than listening to me. If you’d like I can mail you the part file and you can play around with it.

yea i cut back and deleted pro/e, no offense. i understand its pretty powerful, and i cant pull off what you did with inventor. i want to know how Andy Baker pulled his off. Its definally not inventor though, judging by the axis on it. Nice work by the way.

I’m guessing he made it using Unigraphics.

The mobius I made took a while. I am a Unigraphics user, and have been for 14 years (since version 7, I think). I probably had 20 hours into this design, over the course of 2 months (most were during lunch hours). This was a swept solid, through a series of the same profile. Here were the steps taken:

  1. Make the 2d profile of the mobius cross section (in this case, it had 2 grooves in it to contain the 5/8" steel balls).
  2. Save the profile created in step 1
  3. Open a new part, draw a circle that will be the centerline through the mobius will flow. This circle was 7" in diameter, if I recall correctly.
  4. Import the profile from step 1, placing it so that the center of the profile is on the 7" diameter line, at 0 degrees. I did this by moving my work coordinates to that point and importing the profile, instead of moving the profile (you’ll see why I did this shortly). For reference purposes, the Z axis was pointing toward the center of the circle.
  5. I moved my work coordinates up the path of the circle, at 45 degrees, and then rotated the work coordinates 22.5 degrees (360/16), from X to Y.
  6. Import the same profile. This time, since the work coordinates have changed, the profile is 45 degrees up from the original profile, and X is rotated 22.5 degrees toward Y.

At that point, I kept repeating steps 5 and 6, until I got all of the way around to the zero point. By that time, I had 16 profiles along that 7" circle, and through the course of the circle they had rotated 180 degrees.

Once I got all of the profiles in place, I used them to define the swept solid. I think that the UG command is “Swept solid using curve”, or something like that. Initially, I tried profiles at every 90 degrees and 60 degrees, but each of those would make the swept mobius freak out.

Once I got this procedure down, it was about an hour of CAD busywork to make the mobius strip become a solid. I found this out the hard way, since Woodie reviewed my design about 5-6 times, and would ask for tweaks here and there. Each time, I had to create a new profile and import each of the 16 copies at their unique locations and angles. For some reason, the profile would not keep its parametric ability once it was imported into the mobius file.

There… if you followed that, you deserve a cookie.

Andy