bearing valve

thingiverse

This valve features a bearing (or marble) as its core component, and requires specific dimensions such as the diameter of the tube and size of the bearing for proper assembly. First, heat up the bearing in a fire to create a smoother surface that better seals the hole in the bottom part. Then, insert the heated bearing into the tube, gluing together with PVC glue (e.g., using 5/8" PVC tube for the inner tube, 3/4" PVC tube for the outer tube, and two 7.144 mm bearing balls). For a pump, ensure that the inner valve fits smoothly within the outer valve, possibly sealing it with a rubber ring if necessary. This design is inspired by the demo-knikkerpomp from http://www.wot.utwente.nl/publications/demo-knikkerpomp/demoknikkerpomp-v5.pdf.