Devices, systems, methods, and kits of parts for monitoring operation of an electron beam additive manufacturing systems are disclosed. A monitoring system includes one or more measuring devices positioned on the at least one wall in the interior of a build chamber of the additive manufacturing system. Each one of the one or more measuring devices includes a piezoelectric crystal. The monitoring system further includes an analysis component communicatively coupled to the one or more measuring devices. The analysis component is programmed to receive information pertaining to a frequency of oscillation of the piezoelectric crystal. A collection of material on the one or more measuring devices during formation of an article within the build chamber causes a change to the frequency of oscillation of the piezoelectric crystal that is detectable by the analysis component and usable to determine a potential build anomaly of the article.