The supplier now provides these brackets in aluminum only, due to the case-hard skin these thin sections have. We chewed up a HSS and a TiCN coated drill bit before finding a small Carbide ball mill we could use. Even though this little mill had one damaged flute, and really wasn't a center cutting mill, it chewed through the tough cast iron without complaint. Sometimes it is all about getting the right tool for the job, and in this case, it is carbide for cast iron.
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