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Does anyone have any information on when he should appear or how? As he is not seem to be at the location stated on the map.

When this guy is in town offering Cogfrenzy's Construction Frenzy,
the Cogfrenzy's Construction Toolkit reward contains a Pressure Relief Valve.
Once you have three, either from doing it three times over the course of time, or from partnering with other people:
Use all three Strained Exhaust Pipe/Strained Exhaust Pipe/Strained Exhaust Pipes.
Use all three Pressure Relief Valve/Pressure Relief Valve/Pressure Relief Valves in the middle of said pipes.
Use the Big Red Button that appears in the middle.
Doppel Gangers then emerge from The Doppel Gate.
Kill The Doppel Gang for credit towards Rest In Pistons
BTW it's a hidden quest, you don't have to accept it or turn it in. It's like an (invisible) wold quest in that regard - you do the stuff, and you get the (meagre) reward.
BTW BTW, even though the Valves persist in your inventory after quest days, the pipes are only accessible on on such days (when Cogfrenzy is in town).

Walton Cogfrenzy <Chief Architect of Mechagon>