Do you adjust your aim for different spins and speeds?

[CueAndMe]

Forgive me for not having followed this thread closely enough. How about the condition of the balls? After the adjustments for spin, speed, throw, etc., how much more variation do we need to concern ourselves with when comparing balls that are dirty to cleanish to polished?
Thanks guys. You're doing great things here.

 

[dr_dave]

condition effects

Forgive me for not having followed this thread closely enough. How about the condition of the balls? After the adjustments for spin, speed, throw, etc., how much more variation do we need to concern ourselves with when comparing balls that are dirty to cleanish to polished?
Thanks guys. You're doing great things here.

Ball and cloth conditions have a big effect on both swerve and throw. That's why I always report my plots and graphs as percentages of the maximum amounts. You can do a single test to determine the maximum amount of throw possible for a given set of balls (ignoring chalk-smudge-induced cling for now), and then everything else will be a fraction of that.

Squirt changes with cue endmass and the CB weight, but it doesn't vary with ball and cloth conditions.

Regards,
Dave

 

[dr_dave]

overspin is tough ... and unnecessary

Dave,
Here is Mike's video on Overspin:
http://www.youtube.com/watch?v=1WzyxhCl0vs

Thanks. The sand-and-wax-paper trick is a neat idea to show how difficult it is to achieve overspin off the cue tip. Overspin certainly isn't practical in a game situation, due to the risk of miscue. It's also not necessary. Plenty of follow action is possible with natural roll.

Regards,
Dave

 

[Colin Colenso]

I put the link up just before your post Dave.

Colin

Eidt: Oops, didn't see the next page.

 

[Colin Colenso]

Forgive me for not having followed this thread closely enough. How about the condition of the balls? After the adjustments for spin, speed, throw, etc., how much more variation do we need to concern ourselves with when comparing balls that are dirty to cleanish to polished?
Thanks guys. You're doing great things here.

The cloth appears to be the biggest variable in my experience, particularly with adjusting for the swerve that occurs on standard shots with english. You can extend the bridge length / pivot point in proportion to the estimated grippiness of the cloth and still get pretty good results, but slippery cloths make the job easier.

If the balls are super clean then angles will be closer to the LOC (Line Of Centers) angle. Hopefully we play with pretty clean balls most the time.

Maybe at a later stage problems like these can be addressed and systematized to refine the system further.

Colin

 

[Island Drive]

I just change my approach.......

 

[Robert Raiford]

TP A.25 relates tip contact-point offset to spin-rate factor (SRF) to percentage English (PE) or spin. With natural roll, SRF = 1 and PE = 80%.

Also, the diagram on page 5 in TP B.3 illustrates graphically where the natural roll point is on the contour plot square.

Regards,
Dave

Hi Dave,

I appreciate your efforts, but I believe diagram 5 is misleading when interpreting the contour plots for practical use.

Since the CB's velocity (and therefore SPF) immediately begins changing significantly for all tip contact points besides the natural roll offset, and since higher SPFs at OB contact are possible than those initially restricted by the miscue limit, describing the plots in terms of initial velocity and tip contact point seems problematic.

Because what is important is the velocity and SRF at OB contact instead of tip-CB contact, you might consider describing an "effective" tip contact-point offset for your contour plots (ala Ron Shepard in APAPP) instead of the absolute offset mentioned in diagram 5. This would also require expanding the plots' max PE to account for the higher SPFs.

Of course, the qualitative nature of the plots won't change much, but discussing the change in SPF as distance to the OB increases will make their interpretation more useful.

Robert

 

[dr_dave]

good point

Hi Dave,

I appreciate your efforts, but I believe diagram 5 is misleading when interpreting the contour plots for practical use.

Since the CB's velocity (and therefore SPF) immediately begins changing significantly for all tip contact points besides the natural roll offset, and since higher SPFs at OB contact are possible than those initially restricted by the miscue limit, describing the plots in terms of initial velocity and tip contact point seems problematic.

Because what is important is the velocity and SRF at OB contact instead of tip-CB contact, you might consider describing an "effective" tip contact-point offset for your contour plots (ala Ron Shepard in APAPP) instead of the absolute offset mentioned in diagram 5. This would also require expanding the plots' max PE to account for the higher SPFs.

Of course, the qualitative nature of the plots won't change much, but discussing the change in SPF as distance to the OB increases will make their interpretation more useful.

Robert

Good point. I can see how this could be misleading to some (probably most) people. I've added the following sentence below the diagram on page 5 of TP B.3:

NOTE - The diagram above illustrates tip contact positions on the ball, but be aware that the throw values correspond to the spin on the CB at OB contact. Spin changes due to drag on the cloth, as the CB approaches the OB, must be taken into account. For example, the "maximum possible bottom-spin" point at the bottom is possible only for a firm shot over a short distance; otherwise, drag action reduces the bottom spin some, in which case the effective point on the diagram would be a little higher.​

I hope that makes it more clear. I'm sure Colin will make this sort of thing more clear when he presents his system.

Regards,
Dave