In order to choose the best lathe tool rest for any project, the size of the project must be taken into account as well as the type of tooling that will be used on the lathe. For the most part, a lathe tool rest is simply a rest, or guide, against which one end of the tool is placed while being used to cut or turn a project to a desired size and shape. For most projects, selecting a lathe tool rest that is as long as possible will eliminate the need to remove and reposition the rest repeatedly. Shape is as important as size when choosing the correct lathe tool rest, as long open arms will allow the tool to be placed so that it can reach far into an open turning.
Frequent repositioning of the lathe tool rest is required as the square corners of the project become rounded sides and the distance between the tool rest and the turning begins to increase. Ideally, the operator wishes to position the lathe tool rest as close to the turning wood as possible without making contact. Placing the lathe tool rest close to the turning allows the operator to gauge the amount of taper in a piece of wood as well as to identify any high or low spots along the length of the wood.
On a common wood lathe, the lathe tool rest is held in place by a tool holder, a device that allows the rest stand to be inserted into it and tightened in place with a set screw. The tool rest can be turned, angled and raised or lowered by adjusting its position in the tool holder. The holder can also be slid back and forth along the lathe frame or bed to allow the rest to be positioned at any spot along the length of the turning. With this adjustable feature, the operator is able to find a comfortable position from which to create an ornate turning from a piece of ordinary wood.
Occasionally, a tool rest will become scarred and beaten, causing the top edge to no longer be the smooth and steady guide it once was. In this case, the rest is commonly discarded from use on the finished outside of the turning and is used when rough-shaping a block or gouging the center of a bowl. In this application, a smooth cut is not as important as when finishing a project where a fresh and smooth lathe tool rest must be used.