I created these parts to be able to model rubber belts in my Technic creations. As I habitually create my instructions with LeoCad which doesn't allow to use directly Ldraw primitives, I needed parts that could be imported (to import parts in Leocad, goto File > Piece Library Manager > File > Import piece).
This is my first part authoring, so be indulgent...
There are DAT-files for 5 fragments of rubber belt which combined, eventually overlapped, can be adapted to most situations:
- 1/4 turn around Technic Bush 1/2
You can download the DAT files here.
Rubber Belt Generator
I further modified Spring2dat to into a Rubber Belt Generator. This program generates DAT files for rubber belts taut between two pulleys.
The reminder image explains geometrical parameters. All units are expressed in "Lego units" (ldu). 1x1 brick is 20 ldu wide and 24 ldu high.
"Precision" is the number of segments used for half a circle.
If "Use cylinder" is unchecked, Rubber Belt Generator produces square section rubber belts as shown above. If it is checked, rubber belts are composed with LDraw cylinder primitives (4-4cyli.dat).
Download Rubber Belt Generator. (updated 1.1 version, generates BFC certified parts and has more precision)
Dowload belts parts DATs (as above, but using cylinder primitive)
Radius value to use for common pulley (for a 4 ldu thick rubber belt, with cylinder primitive):