The article discusses the process of finishing machining parts with conical holes, diamond honing. The features of the processing process under study are revealed and its differences from cylindrical honing are determined. Conical surfaces honing occurs with a variable contact width of the working surface of the tool with the workpiece, which leads to uneven material removal. According to the developed method based on tensometry, the nature of the distribution of contact pressures of the interaction of the working surface of the tool with the workpiece is determined. Based on the analysis of the results obtained, an experimental design of the honing head for processing conical holes is proposed. Studies have shown that when processing with an experimental tool, equalization of contact pressure is observed. The resulting effect can be associated with the uniform introduction of cutting grains, regardless of the width of the contact. The calculated values of the contact pressures and the contact width of the tool with the surface of the conical hole are also presented according to the formulas obtained during the research. Based on the results obtained, the deformation coefficient is determined as the ratio of the experimental and calculated contact widths in a certain cross section. Introduction to the calculation formula of the deformation coefficient allows you to establish the width of the contact bar with the generatrix of the conical hole of the workpiece more accurately.