An extremely common question we get here at DigiKey is requests for crimp tooling for replacement, repair, or prototyping with common connector types like circular, rectangular, or D-sub. Often, the “Recommended” crimper for these devices can cost thousands of dollars, which is unnecessary when the need is to repair the wiring in your shed, put together a little project with your kid, or prototype a small device for your business. There has to be an alternative at a more budget-friendly price point, right?
For critical applications, or applications which must (or should) pass safety or reliability certifications or inspections, you can find more information on the process and the reasoning behind tool pricing here: How do I select a wire ferrule?
For noncritical applications (with “noncritical” being defined as any application in which lives or significant infrastructure would not be endangered by the application failing), absolutely. Generic crimp tools such as Adafruit’s 5682 for rectangular contacts, Jonard Tools’ WSC-826 for common terminals, or Adafruit’s 1213 as a ratcheting alternative can make for much cleaner, more reliable crimps on a reasonable budget than painfully-priced manufacturer tooling.
While it may be tempting to forego even moderately priced tools such as these and use whatever pliers you have handy around the house, the thing to keep in mind is that crimping contacts is a much more precise science than many believe. The reason manufacturer tooling is often so pricy is because it’s manufactured to exceptionally tight tolerances and geometries and designed to produce exactly the same crimp every time, controlled often to within a few hundreths of a millimeter. This allows the manufacturer to guarantee the performance of any crimp that has been made using their proper tooling by a trained user; without those factors, the manufacturer cannot and will not guarantee their contacts’ performance. If your application requires these guarantees, then unfortunately you will have to invest in manufacturer specified tooling.
Generic tools such as those presented here can achieve a “good enough” crimp for common household, hobby, or noncritical repair purposes, but pliers will not. A proper crimp requires the contact to be squeezed around the wiring from all sides, applying even pressure along the entire circumference of the cable. Pliers cannot do this and will only squeeze the crimp around the wire from two opposite sides, resulting in poor electrical connectivity and a distinct tendency for total failure of the wire-pulling-free or wire-breaking varieties. This cannot be ameliorated by simply pinching the crimp closed with pliers multiple times from multiple angles; doing so only changes the direction in which the pinch happens rather than properly squeezing a crimp shut as intended.