You are reading a single comment by @hoefla and its replies.
Click here to read the full conversation.
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
@hoefla
^^ for roundness I find going slow and spinning the pin works. keep buffing the burrs off and checking.
my dad worked out the formula from first principles, he still remembers optics and stuff, it's basically a compromise between 2 rules/behaviours: that the smaller you go, the sharper it is (since light behaves as a ray) vs diffraction making the image fuzzy with very small pinhole (since light is a wave). I'll dig it out.