7/8"-9 heavy hex nut in Steel, A563 Grade DH. For structural connections and larger bearing surfaces. CARBON STEEL — strong and inexpensive, but it depends entirely on its plating for corrosion protection PLAIN — uncoated — oil it, paint it or keep it dry COARSE THREAD (UNC) — the default inch thread — faster to run down, more tolerant of dirt, damage and plating build-up Specifications Thread size 7/8"-9 Thread Coarse (UNC) Material Steel Grade A563 Grade DH Finish Plain Standard ASTM A563 Drilling & driving reference Clearance hole, close fit 57/64" (.8906") Clearance hole, normal fit 29/32" (.9062") Tap drill at approximately 75% thread engagement. Clearance holes per ASME B18.2.8 / ISO 273. Wrench and key sizes per ASME B18.2.1 and B18.3. Figures are reference values — confirm against your own drawing before machining.
