It was the ghost of Mosconi!
We can now call unexplainable, extreme curvature of CB path the 'Mosconi Effect'
JS said it was chalk, but we did not see an abrupt change of direction which is what chalk does. But what kind of chalk? He said a piece of chalk.
What if it was just a layer of chalk instead? When I shoot certain draw shot drills using the same ball positions, the area where the cue-ball is setup gets a dusting or coating of chalk. Would something like this (not pieces of chalk, but a smear of chalk dust) allow the spin to "grab" more?
From the video I can't tell. Too far, not enough resolution.
I still think the biggest factor here is a slate imperfection. Whether it is a very slight groove or imperfection in the slate, or an issue with the the level....it has got to be a slate issue.
Slate can have dips in it in small areas of various sizes. On any of the 3 pieces of slate, any corner or even an area in the center of any single piece of slate can have a depression or slight rise. Slate can also be warped. Slate can have a dip across the surface, or it can be bowed upwards across the surface. Or it can be perfectly flat 90% of it's width or length, then it can bend downward or upward the last 10% ...I've seen this before.
How a slate is leveled matters as well as the levels used. If the mechanic is using a 12" Starrett machinist level and plants it in the middle of the slate, then turns it 90 degrees to level the other way, that will NOT suffice to catch the above issues.
Or, if they place the level on the 4 sides of a slate, that won't do it either. You'd have to do all the sides, the center in both directions, and the diagonals. In all directions. Or better yet, use multiple levels and still check all directions.
Also...12" level may span a depression in the slate that a 6" or 8" can detect. Most mechanics I've seen use a 12" because it is faster and simpler. It give more of an "average" of level. Because once you use a 6" on a slate, you quickly discover everything I just said - dips, rises and warps. It's a lot more common than people might think. It can get aggravating, tedious and almost pointless to use a short level like that as you will be chasing level back and forth the slate all day long and in the end you can't get it perfect. Sometimes you can fix areas by drilling holes and anchoring. Some will sand down the slate. A very bad piece of slate that has too many ups and downs just needs to be replaced. Most of the time, slight imperfections will not translate to any noticeable ball roll off. Another reason the shorter levels are not the main tool of choice.
Dr Dave did show the ball-turn effect. We should acknowledge it is at least part of that factor since the CB had a lot juice on it. However, it does not explain that much of a radical curve especially in the late stages of the CB's movement.
Figure, high spin ball-turn effect along with a level or slate issue magnified it to create that severe turn in CB path.
Has to be multiple factors working together.
A slate issue can easily go undetected. In 14.1 there's not a whole lot of slow-roll ball action either CB or OB in that area of the table...so it could have gone "under the radar" until exposed at the worst possible time.
JS should slow roll some balls at various angles toward that area and see if there's some roll off or strange CB movement.
