3 sentences

1. 砂轮打磨金属时迸发出耀眼的火星。

   shā​lún dǎ​mó jīn​shǔ shí bèng​fā chū yào​yǎn de huǒ​xīng.

   Sparks fly when the grinding wheel polishes the metal.

   Source: Dong Chinese Dictionary

2. 这把宝剑的刃口经过打磨，变得十分锐利。

   zhè bǎ bǎo​jiàn de rèn​kǒu jīng​guò dǎ​mó, biàn de shí​fēn ruì​lì.

   The edge of this sword has been polished and become very sharp.

   Source: Dong Chinese Dictionary

3. 这件木制家具做工粗糙，表面甚至没有打磨光滑。

   zhè jiàn mù​zhì jiā​jù zuò​gōng cū​cāo, biǎo​miàn shèn​zhì méi​yǒu dǎ​mó guāng​huá.

   This wooden furniture is roughly made; the surface isn't even sanded smooth.

   Source: Dong Chinese Dictionary