A lathe tool post is a special clamping device that rigidly holds the lathe tool or tooling to the carriage of the lathe. A basic lathe tool post is designed to hold one turning or facing tool. More typically, a lathe tool post might hold one or multiple tools, depending on the configuration of the lathe.
If lathe tooling is swapped in and out frequently, a single-tool post might become a hindrance. Often, a single-tool post is replaced by a multi-tool post, quick-change tool post or an indexable tool post. Each of these types of posts can hold two tools or more. Having a tool post that is capable of holding multiple tools might reduce the operator’s setup and/or changeover time between lathe jobs.
To use a multi-tool post, the lathe operator locks the desired tool into place, then locates the center line of the spindle with the cutting edge of the tool. The operator might need several attempts adjusting the tool post and tooling until the lathe tooling has been correctly centered. After it has been centered and clamped, the turning or facing tools should remain with the correct center line orientation while the new tools, also clamped by the same post, are bought into the cutting position.
An indexable tool post allows the operator to unlock, index and re-lock the tooling without disturbing the position of the tooling relative to the center line of the lathe. A quick-change tool post can be easily removed from and replaced onto the lathe. These are especially useful when the tooling requirements exceed the tool capacity of a single post. This way, a series of tooling can be prepared ahead of time and exchanged as needed.
In addition, lathes also can be equipped with a rear tool post. To use a rear tool post, usually the cutting edge of the tooling faces upside down as compared with the tooling on the front tool post. This allows the operator to use both front and rear sets of tooling while running the lathe in the same direction.
Sometimes tool posts can be removed from the lathe altogether. This is done for accessibility or to replace them with optional tooling. Inside diameter/outside diameter (ID/OD) grinding or milling attachments are sometimes used in place of a lathe tool post.