What is the difference between the collets used on the mill and those used on the lathe?
Both types of collets physically work the same way. Collets typically have “fingers” and a taper. When we squeeze the outside of the collet, these fingers tighten, resulting in high static friction and a strong clamping force.
On a mill, we use a collet in the spindle to hold a cutting tool. There are a few types of mill collets, but you’ll commonly use R8 collets on smaller milling machines. R8 collets have internal threads that attach to the mill drawbar. When you load a tool into the mill, the drawbar threads into the end of the collet. Learn more here.
We can also use a lathe collet (5C collet) inside of a collet block to hold round parts on a mill.
On a lathe, we use a collet in the spindle to hold a part. We often refer to lathe collets as 5C collets. 5C collets have external threads that attach to the lathe drawtube. Pulling back the drawbar pulls the collet into a tapered bore, which presses the collet “fingers” against your piece.
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