Definition
A slot is a long, narrow milled channel in a part, which can be open at one or both ends, fully enclosed, straight or curved. Slots are common for features like keyways, guide channels and clearance cuts.
What drives a slot's cost and achievable accuracy
A slot's width relative to available tool diameters, and its length-to-depth ratio, drive both achievable accuracy and cycle time; a very narrow, deep slot forces a thin tool prone to deflection and breakage.
Where it appears on the drawing
As a width and length or path, with depth and, where relevant, positional tolerance relative to other features.
Common mistakes
Specifying a slot width that doesn't correspond to any standard tool diameter, forcing either a custom tool or multiple passes with a smaller tool to achieve the specified width.
A slot's width relative to available tool diameters, and its length-to-depth ratio, drive both achievable accuracy and cycle time; a very narrow, deep slot forces a thin tool prone to deflection and breakage.
See how Blake reviews a partFrequently asked questions
Is a slot the same as a groove?
The terms overlap significantly; "groove" is sometimes used for a shorter or shallower slot, especially on a rotational part, but usage varies by shop.
Why does slot width need to match a standard tool?
Because milling a slot narrower than the smallest practical tool, or wider than a single pass, forces extra passes or a custom tool, adding cost.
Do slots always need to be straight?
No, curved slots are common too, though they add complexity to toolpath generation compared with a straight slot.