Every shop that deals with high velocity or highly complex applications needs to know they can count on all the parts of their assembly and machining setup. This means not just having high quality tools (e.g. form tools, lathes, boring tools, etc) but also reliable and job appropriate tool presetters and tool holders.
You probably are already familiar with a lot of the common machine tools that are held in place by tool holders, or calibrated by tool presetters: gear shapers, hobbing machines, drill presses, planers, shapers, saws, screw machines and grinding machines; all the common types of single or multi edge cutting tools and grinding tools.
When machining materials for commercial purposes, there’s literally no room for error. Parts have to be shaped and cut to exactly the right dimensions in order to perform their prescribed functions. This is why tool holders and tool presetters are so important. Presetters map out the exact motions a tool will need to go through to produce the desired result, and tool holders have to hold their assigned tools firmly in place, without budging, at exactly the right angle.
Tool holders must have precisely cut collets to hold tools in place, and also must have the appropriate taper. What does this mean? The collet is the part of tool holders that actually grips the cutting tool. R8 collets (the kind used in the absence of automatic tool holders) simultaneously grip the cutting tool and hold the tool to the spindle with the same tapered section. These must be changed out with care as they can let the tool itself fall out when released from the machine spindle. The tapered portion of different tool holders vary in their dimensions but mostly lock in place on the same principle, engaging a locking mechanism in the spindle as they slide in.
This information is probably unnecessary for those already familiar with machining, but hopefully it also serves as a reminder of how important tool holders and presetters are in any shop, and how they have to be of top quality in order to ensure safety and a reliably well cut final product.