Small Gauge Train Wheel Tires for Hoverboard Motors
This repository contains FreeCAD and STL files to print your own set of wheel tires. Just in time for a certain summer event at the Ziegeleipark Mildenberg!
Version history
v7: First public release. The design has not yet been tested on real rails.
Filament
Use TPU filament with a hardness of 95A or better.
Successful prints were made with Fillamentum Flexfill TPU98A and Esun TPU 95A as a more cost-effective option.
WARNING: TPU sticks extremely well on PEI build plates and may strip the coating. Use a textured build plate and high Z distance for the first layer.
Recommended Print Settings
- Volcano hotend with a 0.8mm Bondtech CHT nozzle
- 240°C, 100% cooling, no bed heating
- 0.5mm layer height, 70mm/s print speed = 28.00 mm³/s
- Use same speed for everything -- walls, infill, etc.
- At least 2.4mm wall thickness, 3 top/bottom layers
- 33% "lines" infill, concentric top/bottom pattern
- Tune pressure advance at the desired speed and temperature
- TPU needs a high value like 0.1
This will result in 100m of filament / 300g per tire while achieving a fast print time below 3 hours. 100mm/s is also possible, but I had problems with warping (bending and lifting up the entire build plate).
FreeCAD Settings
I used RealThunder's FreeCAD LinkStage3 branch v2023.05.21, but other recent versions should also work.
STL Export Quality
By default, FreeCAD will export very low resolution STL files with visible polygon artifacts.
You can improve this by lowering the maximum mesh deviation:
- Edit → Preferences → Mesh Formats tab
- Maximum mesh deviation: 10µm
NOTE: In typical FreeCAD quirkiness, you have to import an STL file first to see the "Mesh Formats" tab.
See: https://forum.freecad.org/viewtopic.php?p=202630&sid=7fc59b195f00a3d57d245c826f2d6784#p202630
Display Quality
The default tessellation settings are also too low to work with curved lines. Both the Part Design and Sketcher workbenches have their own settings to tweak:
-
Edit → Preferences → Part/Part Design → Shape view tab
- Maximum deviation: 0.1%
- Deviation lower bound: 0.1%
-
Edit → Preferences → Sketcher → Display tab
- Segments per geometry: 500
Updating the text
The embossed text can be updated in just 14 easy steps:
Inkscape
- Edit Text in
drawing.svg - Save as
drawing_path.svg - Path → Object to Path
- Delete helper circles
- Save
Draft Workbench
- File → Import
drawing_path.svg - Delete Frame
- Select all Text
- Modification → Draft to Sketch
- Remove Path objects and second sketch
- Move Sketch to Body
Part Design Workbench
- Select front face of Tire
- Map Sketch to Face
- Finally: Pocket
License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
