Parts of a Spindle – Quill, Bearings, Drawbar and Collet

All 10 parts on the diagram

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Drive and head 3

Motor It turns the spindle through the belt.
Spindle pulley The belt turns it, and it turns the spindle.
Head The casting that carries the quill and the motor.

Spindle and tool 7

End mill The cutting tool; it has teeth on its end and sides.
Spindle The turning shaft; it holds the tool and spins it.
Bearings The spindle turns in them.
Drawbar Tightened, it pulls the collet up into the spindle.
Collet Pulled into the tapered socket, it closes on the tool shank.
Quill It does not turn; it slides to feed the spindle down.
Spindle nose The working end; the tapered socket is inside it.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it. Wikipedia, Spindle (tool) (https://en.wikipedia.org/wiki/Spindle_(tool)), Drawbar (machine tool) (https://en.wikipedia.org/wiki/Drawbar_(machine_tool)), Machine taper (https://en.wikipedia.org/wiki/Machine_taper) and Milling (machining) (https://en.wikipedia.org/wiki/Milling_(machining)), counted as one source; US Army, TC 9-524, Fundamentals of Machine Tools (1996), the drilling, lathe and milling chapters and the glossary (https://archive.org/details/tc-9-524-fundamentals-of-machine-tools-1996). This page is not connected with or endorsed by the US Army. Hints and detail lines are in our own words. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; a schematic of no maker's product, nothing traced. Licence: own work

How it works

The parts of a spindle on a machine tool sit one inside another. This drawing cuts the spindle of a small milling machine down the middle, so the turning shaft, the sleeve and bearings round it and the drive on top all show.

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What turns

The spindle is a hollow shaft. A drawbar runs down its bore and screws into the collet, pulling it up into the tapered socket in the spindle nose, where it closes on the shank of the end mill. The spindle pulley on top takes the drive from the motor through the belt.

What holds it

The spindle turns in bearings inside the quill. The quill is a sleeve that does not turn; it slides along its own axis to feed the cutter into the work. The head is the casting that carries the quill and the motor.

Typed answers take sleeve for quill and draw bar for drawbar.

Questions and answers

What is a spindle on a machine?

It is the turning shaft of a machine tool, the part that holds and spins the cutter or the work. In the shop the word often means the whole turning unit: the shaft, its bearings and whatever is fixed to it.

What are the main parts of a machine tool spindle?

The shaft with its nose and tapered socket, the bearings it turns in, the quill or housing round them, the drawbar and collet that hold the tool, and the pulley, belt and motor that drive it.

What does the drawbar do?

It is a long rod through the hollow spindle. Its lower end screws into the collet or tool holder, and tightening it pulls the taper up into the spindle nose and holds it there.

What is the difference between a quill and a spindle?

The spindle turns and the quill does not. The quill is the sleeve round the spindle, and it slides along its own axis to move the turning spindle and its cutter toward the work.