What Sui Xiong wanted to do was obviously not invent a machine that could work in water like the dwarfs.
Due to his severely limited engineering knowledge, to allow the machine to work well in water, it would have to be water-resistant. Water resistance was accomplished by using a layer of water-resistant paint, but because the machine would be performing a grinding function; the paint would wear off quickly in a short period of time.
Furthermore, bedrock was extremely strong and could be comparable to steel. Sui Xiong could not think of anything that could be used to grind it without itself being worn down.
Actually, what he could use was Orichalcos.
