Möbius Rollers, Blender 3D and Fusion 360

A bunch of Möbius Rollers

I think I was first introduced to the concept of a Möbius strip in high school. This simple yet weird thing that can be made from a single strip of paper, one end given a 180º twist, and then the ends taped together. If you trace the surface of the resulting object, it has only one continuous face, and there’s only one edge. There are also weird results when you cut it different ways.

A Möbius strip is actually an ideal mathematical construct, like a point, plane, or cube. One you make out of paper is a physical representation of that ideal construct, but paper actually has thickness. But, that’s interesting, because what you’ve actually done is made a long, thin rectangular solid into a Möbius cube, which has one surface, and one edge. I made the Möbius Roller to answer a question in my head: What would it look like to inflate the side (edge) of a Möbius strip? (Then I had to add the channel that follows the side with balls that roll in the channel – because it was cool 😀.)

What has that to do with Blender and Fusion? Well, I originally learned Blender in order to make this object. I don’t know if you can make it in Fusion. (I genuinely don’t know, I’d like to see how, if it’s possible.) Anyhow, it wasn’t too hard to find a tutorial for Blender that showed how to make something like this shape, and I adapted it.

Does that make Blender better than Fusion? No. There are advantages to each. For example, making an object from a dimensioned drawing (like an engineering or architectural drawing) is much easier in Fusion than in Blender.

If you’re interested buying one, contact me.

Möbius Roller Update

Part One Here


Finally realized that trying to cut or zip the channels open is just overly complicated, and that (although it seems a little less magical) I should just print in two pieces and glue together. There are multiple benefits:

  1. It looks better. Being able to control the edges of channel where it intersects the outside of the of the cube gives a very clean look, probably better than I’ll ever get trying to open it with mechanical means.
  2. Channel walls come out very smooth. This is mostly the result of the way the slicer processes the model when it’s when it’s a monolithic piece.
  3. Easier to model. There are a lot more considerations when trying to make internal structures in an enclosed piece.
  4. Easier to paint, especially on the inside curves. Although, I do have to take a different approach than primer/sand/spray, which was giving some really nice results.

It’s not done yet, though. As you can see in the picture of it being printed, I did not use supports, and that caused the channels on the top of the arcs to be distorted just enough that the bearings fall out. Reprinting with supports now, and that should add dimensional stability (along with my emotional stability). 🙂

Seeking the Perfect Möbius Roller

I’ve been trying to perfect the process of making these things that I call “Möbius Rollers”.

Issue #1—Painting:

On the top one I used multiple coats of filler primer, sanded it with 100 then 220 grit sandpaper, painted it blue, taped it, painted it green and removed the tape. The paint job came out looking great.

The second one, I used wood filler on the rough areas, which saved me a couple of coats of filler primer. Painted it green, then taped it. But, the tape strips were too small, and didn’t stick well in some areas, so some of the blue paint got under.

Issue #2—Cutting:

There is a channel with ball bearings that ride around inside. In order to get this to print, I have to make the channel just below the surface. Then, I just cut the top of the channel open, so you can see the balls roll around inside.

On the top one I tried different bits on my rotary tool, and when I tried the router bit, I thought it was working at first, but then it skipped all over, and tore the whole thing up.

The second one I tried a grinding wheel bit on a slow speed, and I got a cleaner cut, but it took a long time. Then, after it was open, I tried sanding the channel so the balls would roll smoothly, but I discovered that the channel is pinched in one area, and even a lot of sanding would not open it up. And, even still, I did not like the way the cut came out.

Issue #3—Model:

On my old printer the channels came out wide enough, I don’t know if it’s the slicer, or the printer, but I need to either figure out different print settings, or maybe modify the the model to make the channels bigger. Also, I want to find a way to make the plastic thin enough along the outside of the channel, so that I can pull it open like a zipper.

3D Printed Halftone

I had an idea to 3D print a halftone image by making a grid of holes where the larger holes would be brighter halftone pixels, and the smaller holes would be darker ones, and then I’d light it from behind. I tried several approaches, including one performed after I made this video, and they all failed. Blender 3D was not up to the task of doing a giant boolean operation, and the P5.js SVG library was not up to the task of drawing all the outline squares that I needed. So, I resorted to printing a background (just a large, white rectangular slab) and switching filaments to print the halftone pixels on top in a different color (black squares).

I have a lot of ideas for variations, like a non-solid background, and slicing a larger image and printing it out in pieces. Ultimately, I still want to try my original plan, so maybe Inkscape, or learn some Fusion 360 to see if it can do it, and then maybe openSCAD if that fails.

Here are the software tools I used:

Here’s the Javascript program, if you want to give it a try yourself: http://hipnerd.com/wp-content/uploads/2018/05/3D-Half-Tone.zip

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