The Collector Gutenhagen wants to clear the Pavel Ruins of Golems in order to research them.
1. Go to the Pavel Ruins, there is a small cluster of tents where you will find two NPCs- Yumi and Gutenhagen. Speak to Gutenhagen to start the Influx of Machines Quest (you may have been sent to him by Yumi after completing "Pavel The Giant", but you do not need to complete that quest first).
2. Gutenhagen will send you to go hunt the golems (there's a LONG list that will be listed in your quest guide so I will not repeat them here). There are about 2 or 3 pits where you will find them as well as some of the golems near the archaic laboratory, so pretty much almost any golem you find will fulfill this requirement. The quest item drop rate is not very high, so collecting 500 will go a bit slower than you probably would hope.
3. Once you have collected all 500 golem shards, return to Gutenhagen and he will reward you with a random 60% B grade weapon recipe (Both C5 recipes and previous are possible)