Beginning in about 1951, Michigan Defiance Co. of Big Rapids, Michigan, was manufacturing sharpening machinery for the woodworking industry. This name only appeared for about a decade.
We do not know if there was any connection to Defiance Machine Works of Defiance, Ohio. Given the historic prominence of that firm among makers and users of woodworking machinery, such a connection seems like an obvious connection but more research is needed. Another question for further research is whether there is any connection to sharpening machinery maker Hanchett Mfg. Co. of Big Rapids.