With the hub, I started I used the regular dimensions of 3mm across and 5mm long for the hole by making a circle with a 5mm diameter and removing the excess on the sides with 3mm straight lines. I made the diameter of the entire hub 9mm. I extruded it 10mm then added 3mm (diameter) holes on both sides for the screws.
I then printed the hub on the Lulzbot and noticed some issues. I did not rotate it to the flat side, so it was warped. The hole was also too small for the motor shaft so I measured that and adjusted it using the following calculation: [(5)/(actual size) * 5)] which was [(5)/(4.9) * 5)] = 5.1 and [(3)/(2.9) * 3)] = 3.1. It was still barely too small, but I decided to try again but use the Prusa printer because I usually get better results.
I went ahead and printed the whole wheel, giving it a diameter of 90mm, with the hub attached and extruded to be flush with the face of the wheel, keeping the dimensions from the first modifications and it worked. So, my final dimensions for the hub hole were 5.1mm long – 3.1mm wide, and the wheel was 90mm across with a 3mm thickness.
