Designing an Omni Wheel


I was at a robotics event a while back and saw so many omni wheels I got inspired to try to design one. I remember looking up omni wheels years ago and seeing how expensive they were, so 3D printing my own seemed like an obvious choice.


I mostly succeeded in designing and making one, but it’s also quite a bit of a failure. Don’t get me wrong, it was a fun exercise, and I tend to enjoy a design challenge, but these aren’t gonna work.


I had planned on brushing Plasti Dip onto the wheels to give them some grip, or maybe casting them from Silicone. (Someone else suggested printing with TPU filament.) If I get back to this project I might consider some of those ideas…


So where was my big mistake? When I modeled this, I did not model in the hardware. Sure, I modeled in the holes for the hardware, and what I thought was enough space for the heads of the bolts, but the bolts stick out just a bit too much. As I said, this was a fun exercise, and maybe I’ll revisit it in the future but…


I went looking for omni wheels again and found this VEX IQ 63mm Omni Wheels (2pk) for about $10, which means for $20 I got 4 really nice omni wheels. They might also serve as a reference if I try redesigning my wheels, now that I have a good example to go from. Maybe my choice of 3mm hardware was a poor one. Hmmm, I’m already thinking about the next iteration.


Printing 4-Up

Wheel 1-Up

We’re planning a Nerdy Derby event at Maker Faire Milwaukee, and like last year, I wanted to 3D print a bunch of wheels, and yes, it is fun designing strange wheels. Most of my designs this year are refinements from last year, and I wish 3D printing were as simple as hitting “print” and walking away, but that’s not always the case.

Wheels 4-Up

I found that if I printed one object, it worked fine. If I tried multiple objects, things were failing, either with one or more objects, or everything. I’d try to print two wheels at once, and one would work, the other would fail. Slic3r allows you to generate the G-Code needed to print files, and has an option to print multiple objects, either by printing them all at once, or one at a time. Both of those options just weren’t working for me, for whatever reason. (My 3D printer is a RepRap I built myself, and yes, it has issues now and then.)

But you know the old saying… if you can’t fix it in hardware, fix it in software! So I did… You’ll notice that the image above shows four wheels with a small square connecting them. I ended up pulling an STL file into OpenSCAD (my favorite 3D modeling application) and then duplicating it four times and adding a small 1mm tall square between them to connect it all into what the printer would see as one single object.

Wheels Printed 4-Up

It worked! I’m now seeing much more success with printing, and getting sets of 4 wheels connected with a thin piece of plastic that’s easy to remove. Oh, I should also mention that our friends at Inventables were kind enough to donate some filament to this cause, so if you have fun building a car with 3D printed wheels at Maker Faire, be sure to stop by the Inventables booth and thank them for making it happen.

(BTW, MegaMag is printing way more wheels than I am, and going 40-Up!)


Derby Wheels

If you remember Milwaukee’s last Nerdy Derby, we tried to supply lots of pieces for people to build cars with. I ended up laser cutting a bunch of wheels, as well as 3D printing some wheels… take a look at the junk car post from last year.

Well this year I started printing wheels, and then decided that plain old boring wheels just wouldn’t do, so here I present a progression of wheels I’ve designed so far. I’ve only printed about 1/4 of them, but I’ll probably give them all a try before the big Nerdy Derby event at Milwaukee MakerFest on October 19th, 2013.

The plain old boring wheel from last year.

Speed holes… should use less material, but may not actually print any faster.

Indent, for no particular reason.

More speed holes, this time done using a proper for loop.

Reverse spokes?

Howdy partners! It’s a wagon wheel!

And a steering wheel!

And an Aperture wheel?

Wheel wheel wheel wheel wheel…

Tri-force wheel?

Weird wheel?

Starting to do some hull action for more 3D-ish wheels.

I will say this, I am no expert at designing wheels, but it’s been a lot of fun and a great design challenge, and I really do enjoy tinkering with OpenSCAD to create things.

Oh, and then I wanted to do a spiral wheel, and did some searching, and found this great wheel library, so use that if you really just want awesome wheels and don’t care as much about screwing around with code to learn things on your own. (Or, us the Highly-Configurable-Wheel library and learn from it!)