My first attempts at building 50-conductor cables with
header
connectors on one end and card edge connectors on the other to
interface between a Pertec tape drive and controller resulted in a few
broken connectors before I gave up and bought a proper press.
The only time I've (recently) had connectors break when crimping them in
the vice was when I accidentally bought cheap, cr*ppy connectors. I
bougth some Farnell own-brand 50 way Microribbon plbus and had no end of
trouble. When I foudn they also solde 3M oens (admittedly at 6 times the
price [1]), I used those and had no further problems
[1] The cheap oens were linekd from the 3M conencotr page, but not the
reverse...
-tony