Valheim Blast Furnace | How to unlock and craft Wednesday, February 10, 2021 Valheim might look simple, but there are tons of components to gather and craft into helpful items. In order to turn Black Metal Scrap into Black Metal Bars and make better gear, for example, players first need to unlock and build the Blast Furnace. So, here’s how to get the Valheim Blast Furnace on PC. How do you get the Blast Furnace in Valheim? Iron Gate’s Norse Viking survival game, Valheim, can be tough to get to grips with. These beginner’s tips and tricks can help during the early stages, but even later in the game players still encounter new mechanics. Amongst other things, these include furnaces and smelting.