Nut thread missing

Have also seen this before. Threads missing from nuts, or even parrallel grooves instead of thread.

We looked at "vision" system for electronic detection in the feeder unit, but eventually used a threaded mandrel to pick up and locate the nuts while fitting. This meant that faulty threads were never installed because the mandrel failed to reach a "stop" through the nut.

The benefit was that the mandrel also stopped weld splatter from getting into the thread.

The nut supplier was not sympathetic to our situation. Purchasing decision to maintain cheap supply for the nuts.