🔍 Key Concepts

• Hand hacksaw blade selection depends on the hardness and thickness of the metal • Harder or more brittle materials usually need finer teeth to avoid tooth breakage • Fewer teeth per inch means coarser blade; more teeth per inch means finer blade

💭 Think About

• Is drill rod and tool steel generally harder or softer than mild steel or aluminum, and how does that affect tooth size? • What might happen if you try to cut hard, small-section metal with a very coarse blade? • What kind of tooth spacing helps keep several teeth in contact with a hard workpiece at the same time?

✅ Before You Answer

• Compare which choice has the finest teeth (most teeth per inch) and which has the coarsest teeth (fewest teeth per inch) • Think about the size and hardness of drill rod and tool steel versus something like thick, soft bar stock • Recall the usual guidance: hard, thin materials → more teeth per inch; soft, thick materials → fewer teeth per inch