This paper summarizes the results of a research study carried out for the selection of the mechanical cutting equipment in a Celestite Mine which is situated in Sivas, in Northern East of Turkey. Surface mining method using drill and blasting techniques is currently used in the mine. However increasing stripping ratio and other mining difficulties initiated the company to put forward a new research programme to look for the possibilities to change the mining method to an underground mechanized system. Within this programme large Celestite and bedrock (anhydrite and gypsum) samples were collected from the mine and they are subjected to wide range of cutting tests using small scale and full scale cutting rigs developed under NATO-TU Excavation project. A testing programme using a conical bit, with different depth of cut and tool spacing was carried out on samples collected from the mine. Cutting and normal forces and specific energy values were recorded for each test and results were analyzed in order to estimate the daily production rates of the machine. At the end full scale and small scale cutting tests were compared and criticized for optimum selection and performance prediction of mechanical excavators.