'Driveline' silicone tubing and balls, for constant velocity couplings (universal joints)

click here for construction and assembly notes  (also available as a pdf)
Example of 0.8mm square and 0.8mm round shafts coupled with 1mm o.d. 0.5mm i.d. 0.25mm wall thickness tubing with a 1mm ball

Shaft diameter: Tubing size Recommended
ball size:
Overall diameter Bore diameter Wall thickness
2mm or 3/32" 3.5mm 1.5mm 1.0mm 3mm (or 1/8")
1.5mm or 1/16" 3mm 1.0mm 1.0mm 2mm or 3/32"
1.5mm or 1/16" 2mm 1.0mm
0.5mm extra flexible
thin wall
2mm or 3/32"
1.0mm or 0.8mm (1/32") 1.5mm 0.5mm 0.5mm 1.5mm or 1.0mm
1.0mm or 0.8mm (1/32") 1.0mm 0.5mm
0.25mm extra flexible
thin wall
1.5mm or 1.0mm

Balls, stainless steel: available in the following diameters: 1.0mm, 1.5mm, 2.0mm, 3/32", 3mm.

Balls, delrin: available in 2mm diameter.