A Car Stand for a OneWheel Pint

My son rides around on something called a OneWheel. It's like an electric skateboard but it has only one large tire and it sort of self-balances. I think he's nuts, but what are you going to do?

The OneWheel weighs about 9 kg. When he transports it his car, its odd shape allows it to tumble around every time he hits the bakes or gas or turns, so he needed some sort of stand for it that would hold it stable and keep it from damaging the back of the car. He showed me a couple designs for stands on Thingiverse, but as is often the case with models on Thingiverse, they are best used to illustrate how not to do something.

I started my design the usual way, by making a 3D model of the OneWheel with just the pertinent details modeled to the accurate dimensions, measured with a caliper and measuring tape. I used that model to design the stand. The design has a large, flat base, 286 mm in diameter by 6 mm thick, that is a silly waste of time to print. It would be more sensible to start with a wood, metal, or plastic base, either round or square, and then screw down some printed parts designed to hold the OneWheel, but I didn't have any suitable material on-hand so I went ahead and printed the stand with the large base.

CAD model of the OneWheel on the stand. The side of the tire and wheel rim rest on the stand.

The tabs just fit into the rim of the wheel but don't interfere with the valve stem.

Print in progress on UMMD- it took about 10 hours and 45 minutes, about half of which was spent printing the large circular base, and used 307 g of PETG filament.  It was printed in 0.3 mm layers at 50 mm/sec with 20% triangular infill, 4 perimeters, 0.5 mm line width, and 4 top and bottom solid layers, in one piece without supports.

Here is the OneWheel on the printed stand. Like our genius president, it's quite stable!

Aeropress Coffee Maker CAD Model

The Best Coffee Maker

I love my Aeropress coffee maker, and the coffee I make with it. I love it so much that over the last 7 or 8 years I've replaced it two or three times when the rubber seal gave out. Well, it's done it again. I decided to spend some time researching my replacement options. I figured that some company in China has to make a copy of the Aeropress that costs about $5. But after an extensive search, no such luck. Then I checked amazon.com by searching "aeropress rubber" and bingo!  There were 5 or 6 listings for new rubber seals for the Aeropress for $5-7 which is a lot more attractive option than shelling out $30 for a whole new Aeropress.

Then I thought about making my own seal. I checked thingiverse.com and youmagine.com for models and found none. So I decided to make my own model and then try printing a new seal with TPU. Now I know what you're thinking. Is it going to be safe to drink coffee that's contacted the TPU that's been 3D printed? You know, I don't know for sure, but then again, I have no idea about the safety of the original or the replacement rubber seals either. I know this- when I took the old rubber seal off the plunger I found about 2 years worth of coffee residue under it. I doubt my little TPU plunger seal is going to be any more unhealthy than that.

I proceeded to measure and model everything that normally comes with an Aeropress. That will make it easy to design storage racks, etc.  

The yellow seal is the printable version, the black one is the original.

The CAD model can be downloaded here: https://a360.co/2TP0ZWn

Note: the model isn't perfect- the little tabs on the filter cap are actually ramps so that as the cap is screwed down, it fits tightly and seals. In my model, those tabs are flat. There may be a similar taper in the receptacles in the barrel where the cap tabs contact, but I can't measure it if it's there.

It took 3 iterations of the plunger seal to make one that works reliably. The yellow one in the CAD file is the final version of the printable part. I used TPU filament, 4 perimeters, 0.2 mm layers, 6 top and bottom layers, and 10% triangular infill.  Be sure to set the seam as "random".  No support material is needed.  The nice thing about the orange TPU I printed it with is that it's semi transparent so I can see if there's a bunch of coffee residue under it.

I'm going to go make a cup of coffee...

Update- the very next day

Well, my printed seal isn't so great. It isn't very compliant and the inner diameter of the barrel isn't constant and maybe not even perfectly circular, so sometimes the plunger is easy to push, sometimes it's hard to push, and sometimes the seal leaks a little.  I think I'll buy one of the rubber replacement seals...

Update a couple days later

I bought this replacement seal and it works great! It's made of a nice, compliant rubber and seals well in the barrel. We'll see if it lasts...

Update November 29th, 2020

The rubber seal is still looking and working like new. Definitely worth the $6 invested.

The tube hasn't developed and fissures in the walls like the old ones did (I wish I had taken some pictures- they looked like lightning with lots of random twists and turns). I think I read something a couple years ago about the manufacturer changing the plastic they use to prevent that.