Here is an excerpt from ‘Lost City of the Incas, The Story of Machu Picchu and its Builders’ by Hiram Bingham, on Inca metallurgy.
There is no mention of saws, but it is an excellent overview with some good details about how the people of c. 1400 Peru manufactured and employed metal tools. Machu Picchu was built about 900 years after Puma Puncu, but many of the technologies used overlap.
Here is a passage of interest to the current discussion:
Some [bronze] axe blades bear evidence that they were used upon stone. Their structure shows severe damage of a character which could only result from very hard usage. They were probably used in cutting square holes in ashlars and in making sharp inside corners. It is difficult to conceive of any stone tools that could have been used successfully for this purpose. Some writers have assumed that the Incas use bronze implements to a large extent in finishing their best stone work. It seems to me, however, that even their best bronze was too soft to last long in such activities. It is not likely that it was often so employed. Experiments made in our National Museum have demonstrated that patience, perseverance, elbow grease and fine sand will enable stone tools of various shapes to work miracles in dressing and polishing both granite and andesite.
So here we have Bingham, the expert archeologist on this region and its people, discussing how bronze axes were used to cut square holes in stone blocks and "making sharp inside corners"; and that "Experiments made in our National Museum have demonstrated that patience, perseverance, elbow grease and fine sand will enable stone tools of various shapes to work miracles in dressing and polishing both granite and andesite."
Please place this in your proverbial pipe, and smoke of it.