I'll take a look at the whole thing later, but to start: effet de moire would likely be a mottled or shimmering effect. Vilbrequin--a tool, bit or brace. Corroie is a form of the verb to weld. (Corroye is the past participle: welded.) Derochement is clearing the rocks out of something; perhaps removing impurities in this case. I think trancha is probably tranche, which in general means a slice or piece of something, but I think I've seen it applied to barrels--although not sure in what context.