If anyone here has an espresso machine with a metal filter basket, do you know how the holes in the filter are made? They are too small to use a drillbit (too small for me to measure anyway - I'd estimate
0.25mm or less)
In my collection of samples, I have two of chemical milling (etching). The small diameter of the holes and cleanness of edges, viewed through a microscope, is impressive. Do a search for Buckbee - Mears Company, St Paul, Minnesota.
I've played about with deforming soft metal around a thin steel wire, to make gas jets, for example, but only in brass, copper and aluminium.
Joules
Photo resist followed by acid etching?
Laser?
Regards, Tony
Depends how thick the filter sheet is, could be many things. Laser is a possibility, so is water jet, or even fast hole EDM (plunge wire eroding down to 0.004"/depth down to 300 x dia)
Peter
Small holes can be drilled in some materials using a "conventional" drill. Routinely holes are drilled 0.2mm in polymer, can drill 0.1mm but don't like doing it. A new machine with 120,000 rpm spindle is claimed to drill down to 0.045mm.
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