Rick,
That graph was a key to predicting the pivot points for swerves of all lengths and speeds. The one you posted. Long and slow needs about 8 inches extra pivot length. Long and firm 2 or 3 inches. 2 foot and slow, an inch or two, 3-4 feet and medium speed, about 3 inches.
You can actually measure half a dozen reference shots on your own table to act as a guide. Would take about 20 mins and you'd have a chart for that cue and those playing conditions.
If you do it often, you can guess within a inch or two, the required effective pivot point for any speed and distance from CB to OB, which is as accurate, perhaps more so, I believe, that guessing the offset using parallel and aiming away from the target to guess the squirt and swerve combination.
And one significant difference is that if you align parallel, but are several inches away from the effective pivot point, then if you hit more or less tip offset than intended, you'll have extra variability. So my method is largely independent of how much tip offset I apply. At least, that's what my testing indicates.
That's one pretty significant variable to be able to take out of the equation. When you get down on the shot and realize you want more english than originally aligned for, you don't need to reposition the bridge, just pivot wider or narrower.
Hope that makes sense.
Try a 6 foot fine cut with OB near the pocket. Played at a slow-medium speed, keeping the speed constant and adjusting the bridge until you're making it with near max offset, using aim and pivot method. You'll be bridging around 16 inches, depending on your cue and table and your speed of shot.
Once you get that shot working, pivoting from the same distance, try 1/4 tip pivot, 3/4 tip pivot etc and they should all work pretty well based on my testing.
Note, that with near max tip offset, you actually need to stroke the cue about 20% harder to get the same CB speed as with 1/2 tip offset. More of the cue's energy is transferred into spin. Keep this in mind when trying to achieve constant speed as it might lead one to think the lower tip offsets aren't being cancelled out to the same degree. Where in essence, you'd be comparing a slow-medium shot to a medium speed shot.
Colin
Colin,
I hear what you are saying & understand, but the thing to me is that I am not going to be playing on the same table with the same friction or in the same weather, temp & humidity, that affect swerve.
To me, & maybe it's just because I have been playing with even extreme off set for so long & in changing weather from morning to afternoon to night, but I just don't see a mechanical method being able to help ME much. I'd just rather rely on my HAMB subconscious.
I'm sure for some it might be a good rule of thumb type format.
It IS very interesting, but I doubt that it will be something that I will employ. That is not to say that others should not do so.
As always it's up to the individual.
Maybe if dementia kicks in & my subconscious goes haywire I'll need it then.:wink:
Keep up the good work. I''m sure this will become a good thing that may help some of those that are afraid of english to get involved with it as they will have something substantial from which to work.
Cheers.