Archive for January 18th, 2020
The hollow punch included with the 5.5 mm eyelet / grommet set had a rather blunt cutting edge:
The rainbow colors along the tapered cut suggested at least token hardening of the edge, so I mounted it in the lathe chuck, deployed a rag over the bed ways to collect the dust, and spun it at a few hundred RPM while freehanding the edge with a Dremel heavy-duty slitting wheel resting on the compound:
It’s not what you’d call “hollow ground”, but at least the edge doesn’t force the outside of the cut surface quite so far outward.
The Tek Circuit Computer decks get their pivot holes cut with a drag knife on the MPCNC, but I won’t be too embarrassed the next time I deploy this thing.