Skateboard wheel 100mm

The wheel is 100mm diameter and has several features that makes it better than regular PU ones:

It has full tire groove for better grip, being 95% air inside helps in amortization (it's a lot more comfortable to ride it on terrain at high speed), AND if it gets broken it is easily replaceable (just print a new one).

Additional materials:

To assemble everything you need 6 4mm x 40mm screws (preferebly cylinder-shape head 7mm in diameter), 6 4mm nuts and 2 skate bearings. All that is for one wheel.

Make sure your printer is TPU ready before starting it. The wheel requires many retractions for your extruder to make, it's better you be certain it won't clog itself midprint. 

The core consists of two parts, both can be printed with PETG. I tried ABS at first, thinking it would be better, but after some tests I found out it has no advantage in daily use (my electric skate is perfectly ok after many miles on high speeds). 

Probably due to a filament/enviroment/printer the holes on the core parts can be either too tight or too loose. My recomendation is to adjust the flow if needed, but your goal is only to make screws go through and meet the nut. Don'use power tools when screwing in, nut can rotate in the channel, and you don't want it because it won't let you put in the screw.

If your ball bearings don't fit you can use sandpaper or any other method to make the hole bigger. If it is too loose just put a drop of super glue and let it spread evenly around the opening so when it dries it makes bearing fit tighter. Either way tests show it's easier to fit it afterwards than trying to catch perfect size with scaling, flow rate or CAD modeling (printers and filaments differ quite extensively in their “performance”).

Printing settings for tires:

layer height 0.2

outer walls 10 perimeters (probably you can go lower, but i wouldn't)

top and bottom 15 layers

infill 5% (heigher makes it denser, you don't want it)

no supports

otherwise use your TPU settings, thus go slow.

Printing settings for cores:

layer height 0.2

outer walls 6 perimeters

top and bottom 8 layers

infill 33%

no supports

otherwise use your average PETG settings

P.S. Wheels made out of TPU can be pretty tough, I deliberately “scorched” them on the asphalt to check (shown on the skate pic). It melts up only reaching certain temps  but to make it happen you need to really grind them up in the same spot.

P.P.S. Make sure when assembling to follow the same tire pattern and to install wheels short core side facing each other on the axis (use photos as references).