lead cropping spinner plate?

Generically I call that lead trimming. Best RPM is 1200-1500 for the blades I've used, which are 3" or so diameter. You need a very sharp blade to cut leads above the surface of the solder. If you trim down into the solder just a bit, a dull blade will chop through neatly, and, obviously, if there's no free lead remaining, it can't very well bend over.

You don't describe your process. We have a custom engineered trimmer for some round boards we do by the thousands, and we fixture some other boards in a milling machine vise and run them past the cutter fairly rapidly (40 inches per minute of feed.) However you do it, the board must be fixed securely, as per any cutting operation.

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Yup, sure makes a mess when one corner of the board is not seated properly :-( We found that using this method on single sided boards with good lead clearance holes led to a rash of cracked solder joints. I imagine that that would be worse with lead free solder.

Neil S.

I think Ferguson when at Gosport was the last time I actually saw one , but I don't remember the cutting action. Is it a knife action plain or serrated or diamond/grit edged grinding action ?

I supose a term for the non-cropped bits could be "swinging chads"

Rotary blade, hardened tool steel. Dead flat on one face, ground to a sharp edge from the other face. Flat surface obviously faces the PCB.