def set_support_dimensions(loading_span=10e-3,support_span=20e-3):
    """set the jig dimensions
    
    inputs:
        loading_span:
            default 10mm
        support_span:
            default 20mm
    
    """
    
    
    dims = {'loading_span':loading_span, 'support_span':support_span}
    dims['spanratio'] = loading_span / support_span
    return dims