On Fri, 2 Dec 2016 07:17:31 -0500, "Jim Wilkins"
wrote:

"Michael A. Terrell" wrote in message
news
Jim Wilkins wrote:
...
The frames broke on these, near the die. I wore out a lot of
punches, before the frame died of metal fatigue. I used to do a lot
of prototyping, with hand tools. Trimming fiberglass circuit boards
to fit into a case was the worst for wearing out the tool.

I've worked at a few places, notably Mitre, that had good facilities
for both electronic and mechanical prototyping but that wasn't the
case at smaller startups developing some new idea on a tight budget.
I've nibbled, filed and sanded a lot of circuit boards to size
including the mechanical-fit models for the Segway balance sensor
assembly. At one place when the Dremel died I cobbled up a pump drill
to finish a circuit board. Unlike a bow drill it applied no side force
to the fragile carbide bit.

http://cart.occpaleo.com/stonetippedpumpdrill.aspx

For that price they could at least have found a prettier smoothed
river stone for the weight.

Do those rely on the inertial force of the spinning stone to work?
Wind 'em up, push down, and they spin until wound the other way.
Rinse, repeat?


--
We cannot but pity the boy who has never fired a gun; he is
no more humane, while his education has been sadly neglected.
--Henry David Thoreau