Under extrusion is awesome!

Ok, so i may have jumped the fence on the caption but i really mean it. While under extrusion can be one of the more annoying problems you can encounter while 3dprinting why not use it for what it is?

TPE

Let me explain. Tires for the OpenR/C cars are 3dprinted in various “rubber like” materials such as TPE/TPU. They are ok and as for the OpenR/C Truggy they work pretty well. But for the OpenR/C F1 it´s a different story as they are smaller, have less weight pushing them onto the road and due to their size it´s hard to get them as soft as you would like for it to obtain proper grip. And even though the material itself doesn´t get as soft as rubber one can actually make the tire alot softer by intentionally under extruding the tire infill.

Playing With Infill

Three settings that matters in this case are bottom/top thickness, infill and number of outlines. Adding more of each makes the tire harder and they depend on each other. The top and bottom needs to be as thin as possible otherwise making the flat part of the tire wont help you much. The infill percentage needs to be high enough to offer support for the top layers and of course the less outlines used the better. (We are not considering wear now).

Other Settings

So i did some experiments and it actually came out better than expected. I´m using 2 bottom layers, 3 top layers, a 5% infill and a single outline. I have set the extrusion width for the infill to 50%. The top surfaces are barely closed but in this case i´m willing to make a exception and let function go before looks.

I´ll just add a coat of silicone and go see these bad boys are made of!

Video