Abstract: The magnetic base assembly includes an electromagnet assembly with a top surface open magnetic pole. A shunt plate is magnetically held to the top of the electromagnet. A canting or tilting of the shunt plate results when accidental side or pulling away contact is made between a riveting processing tool and an extending portion of the aircraft part being riveted as the tool is moved from one riveting location to another. The canting or pull off of the tool prevents damage. The operator can observe the tool canting and stop the tool movement or a micro switch or proximity switch senses the canting or tilting automatically so that the tool can be stopped before damage occurs. The magnetic field can be dynamically controlled to provide adequate pulldown force for the riveting function but a breakaway force less than the amount which would cause damage.