Are there standards for the sizes of the pockets on different tables?
There are standard sizes (and other geometric specs), and they can be found on the WPA equipment specifications page. An illustration of the different parameters can be found on the table difficulty factor (TDF) page. However, not all tables are made the same. Rails and pockets can vary significantly from one manufacturer to the next. The side pockets are usually larger than the corner pockets, especially on larger tables; however, on many coin operated “bar boxes,” the opposite is often true. Pockets are also sometimes “shimmed” to make the openings smaller to make the table play “tougher.”
Does the effective size and aiming point for a pocket vary with speed?
Yes. See the diagrams and examples in the articles in the answer to the next question below. Also, here’s a good video demonstration of this effect:
Does the effective size and aiming point for a pocket vary with approach angle?
Yes. See the diagrams and examples in the following instructional articles:
- “Just How Big are the Pockets, Anyway – Part I” (BD, November, 2004).
- “Just How Big are the Pockets, Anyway – Part II” (BD, December, 2004).
- “Just How Big are the Pockets, Anyway – Part III” (BD, January, 2005).
For example, with a corner pocket, at shallow angles to the rail, because the object ball can glance off the rail well in front of the pocket and still go in, the effective “size” of the pocket is much larger at that angle.
As shown in Diagram 3 in “Just How Big are the Pockets, Anyway – Part I” (BD, November, 2004). The “offsets” are measured relative to the geometric center of the pocket at the leading rail edge of the pocket jaws. The offset vs. entry angle plots near the ends of TP 3.5 and TP 3.6 show how the “target center” varies with entry angle. For a slow shot, the point varies by as much as about 0.6 inches for a typical corner pocket and about 0.3 inches for a typical side pocket.
For experimental results showing how the pocket size and center vary with angle, speed, and spin, see:
- “Where’s the Pocket? … They change size and shape,” (Bob Jewett, BD, May, 2013).
- “Get-In English, At Last,” (Bob Jewett, BD, June, 2013).
Here’s a useful app from slach on AZB that lets you select a pocket and shot speed (slow or fast) and move the CB and OB interactively (with the mouse). It then reports shot margins for errors and other interesting information for any shot:
Pool Shot Analyzer (requires Java to run)