The invention discloses a lathe which comprises a carriage, a rotating chuck, a top seat, a central spindle, a pair of first milling cutters, multiple second milling cutters and multiple sliding mechanisms located on a blank clamp of the carriage. Each sliding mechanism comprises a locking bolt, a sliding block and a pair of clamping mechanisms which are oppositely arranged on the sliding block. The sliding blocks are arranged in sliding grooves of the blank clamp. The front ends of the locking bolts penetrate a guide groove of the blank clamp and are in threaded connection to the sliding blocks. Each second milling cutter is located between the corresponding pair of clamping mechanisms. Each clamping mechanism comprises a pair of clamping arms and a tension spring, wherein one end of the central spindle and one end of the blank penetrate the part between the pair of clamping arms, the front ends of the pair of clamping arms are connected through the tension spring, cams are arranged at the tail ends of the pair of clamping arms, and the cams can abut against the side face of the blank. By means of the lathe, the tool distance can be simply adjusted so as to adapt to test blocks of different lengths, and the cutting accuracy is high.