The blacksmiths of Guédelon have the mission not only to manufacture all the cutting tools used on the construction site by the various trades but also to take them back, temper them, and sharpen them. They constantly transform unusable tools into smaller pieces to offset the cost of iron and the difficulty of its production. For example, over the year, they maintain a stock of two hundred and fifty tools for the stonecutters and masons, producing around fifty of them and recycling another fifty. Such a process makes it possible to permanently leave ten tools for each worker to work with while the blacksmith reforges the worn out ones. The steel used in the forge is a hard steel that contains 0.7% carbon and it is heated to 1,742°F (950°C) to soften it and give it the desired shape. It was chosen by comparison with the extremities of steel-cut medieval tools. The blacksmiths also manufacture the gates and door hinges as well as the safety parts for the lifting gears and scaffoldings.