Surface roughness and chip geometry are the main considerations in the machining process, especially in the turning process. The parameters that affect the surface roughness and geometry of the chip in the lathe process are the depth of feed and spindle speed. With the aim of knowing the surface roughness and geometry of the chip in the lathe process, testing with ST material is carried out. 60 as an effort to get surface roughness and chip geometry as expected. Tests were carried out to analyze spindle rotation variations, with machining and constant parameters. To find out the difference in spindle rotation speed theoretically and empirically, repeated tests are performed. Using Mitutoyo SJ-210 and Micrometer to obtain surface roughness and chip geometry after turning. From the analysis results it is found that the low surface roughness value is 0.214 µm at 4000 rpm spindle speed variation and continuous chip geometry. Judging from the analysis of the F two-way test with interactions, the results obtained F_calculate = 4.30520 <F_table = 4.75, it can be concluded that the variation of the spindle rotation speed with the same depth does not react to the relationship between the value of the ratio of the thick chip thickness and surface roughness. Keywords: surface roughness, chip geometry, spindle rotation speed.