I made a set from some Hi tensile (A-514) steel on a 5' rice tiller one time. I broke the mounting bolts so they fell of and some bent over. Buy new tines from Tillerblades.com $3 apiece. 3 Pt tillers tines need to be spring steel anything else is a waste of time, I been there. I've converted grey market rice tillers over to the flange mount type blades and used KingKutter blades then, but, it's a lot of work and takes a welder and cutting torches and drill press. Soft steel for tiller blade just won't work, they'll fold up like melted butter. bjr