Slots are required on many different kinds of parts. Samples of various types of slots are shown in Figures 1A, 1B, and 1C.
External slots are usually cut with manufactured standard size saws or cutters. Using standard size widths is strongly recommended to reduce costs.
All slots have common characteristics. Primarily, producing a slot will create a burr. Whether or not a burr can be allowed and where it can be permitted should be specified on the drawing.
Slots should be located and dimensioned as shown in Figure 2 with the tolerance from the centerline of the slot. Since most slots are produced with a circular cutter, a radius is left at the bottom. If a flat bottom in the slot is required, this should be spelled out in a note.
Figure 3 shows how the relationship of a slot to another surface on the part should be spelled out in a note. If the relationship to other surfaces is unimportant, this too should be noted because it could reduce your cost.
Internal slots, as shown in Figure 1C, are usually produced by broaching. Dimensioning should follow the same suggestions as outlined above.
If possible, a chamfer should be allowed deeper than the slot. This will avoid or minimize burrs in free cutting materials.