“Work” is the stock you have and part you are creating. Workholding is a critical part of the machining process. If your part is not held properly, it can cause damage to both the part and the tool/machine. This can be due to intense vibrations or the part flying out of the vise. If the part is not held well, it can also blow tolerances, i.e. not being held parallel.
Vises
There are many types of workholding for mills, most of which can be traced back to a vise of some sort. Vises are clamped down to the table in some way, and are used themselves to clamp parts. On a mill, vises usually have removable handles to make sure they don't get hit by the machine or vibrate off.
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The parts of the vice that physically hold the parts are called the jaws. These are usually swappable so the ideal ones can be used for each job.
Standard Vise Jaws
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These are the jaws that come with a vise, and are typically left on. They are ground to be entirely parallel. They are the most common type of jaws for holding any typical parts.
They sometimes used in conjunction with parallels. {See -link-}
Mitee Bites
Mitee bites are an incredibly powerful tool. They allow you to grab onto very thin sections (<0.1” of material).
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The ones that can be used for round parts must be used thoughtfully. They do not hold parts concentric. It is best to use them for earlier operations, and then not used when the part it flipped over. If machining an outer circle, the outer edges will not line up nicely. If machining a top face, it will not be parallel to the bottom face.
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Soft Jaws
Soft jaws are jaws that are usually made yourself out of plastic or aluminum. They are shaped to match interesting contours on a part that are not easily held by workholding methods in the shop or easily sourceable.
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