Tool posts of several designs are available to support and hold the cutting tools in lathe machines. The image below shows the part drawings of a single tool post, which supports one cutting tool at a time and is used on small sized lathes. This unit is fixed on the compound rest of the lathe carriage.
The single tool post consists of a circular body 1 with a collar at one end and a threaded hole at the other. A vertical slot is provided in the body to accommodate the tool/tool holder. The body is slid through the square block 5, which is finally located in the T-slot, provided in the compound rest. The design permits rotation of the body about the vertical axis.
A circular ring 4 having a spherical top surface is slid over the body and wedge 3 is located in the vertical slot. The tool/tool holder is placed over the wedge. By sliding the wedge on the ring, the tooltip level can be adjusted. The tool is clamped in position by means of the square-headed clamping screw 2, passing through the head of the body. Figure 19.8 shows the assembly drawing of a single tool post.
This is used to hold four different tools at a time. The tool holder may be rotated and clamped to facilitate the use of anyone of the tools at a time. The details of the square tool post are shown in the image.
The tool holder 1 is located on the base plate 2 by means of the stud 3. It can be fixed to the base plate in any position rigidly by the clamping nut 4 and handle 5. The knob 6 is fitted to the handle for smooth operation. The tools are held in the tool post by means of the set screws 7.
Each tool can be indexed readily by rotating the tool holder on the base plate and located in the correct position by the spring 9 and the ball 10. The ball is seated in the V-groove, provided for this purpose in the base plate.