[Mike Schreiber]

I've attached a semi worked out solution. You should be able to plug in your numbers to these equations. I assumed the shaft is 6.35 mm or 1/4 in stainless steel. I don't know what it is actually made of but you want to look up the yield stress. Once you solve for the moment, that is equal to force applied * distance cantilevered. If you need more help just ask.