If deflection isn't slide you mean the cue ball rolls sideways off the center line? What about a stun shot where there is no roll at all? Isn't the cue ball sliding off center then when it deflects?
I would like to hear Dave's idea on this point. When a cue ball deflects is it sliding, rolling, some of both or it doesn't matter. If it moves to the left (with right English) it has to be doing something to get there and if it isn't rolling at all it seems like it has to be sliding.
First, we need to be careful with terminology. Total or net or effective CB deflection is the end result of of both squirt (sometimes also called "deflection") and swerve. Throw also affects some shots (some more than others). A complete summary and demonstration of all squirt, swerve, and throw effects can be found here:
complete summary of all squirt, swerve, and throw effects (with supporting resources)
CB slide or ball/cloth conditions have absolutely no effect on the amount of squirt. For more info, see
what causes squirt.
Swerve depends on shot speed, shot distance, the amount of sidespin, cue elevation, and ball/cloth conditions. See the
effects summary resource page for explanations and demonstrations.
Vertical tip position (for draw and follow) also affect squirt and swerve. For more info, see:
squirt and swerve draw and follow effects.
Again, net CB deflection is a result of the combined effects of squirt and swerve.
Assuming it could be doing either the friction of sliding would seem to come into play more than on a rolling ball. I think that is what Dave means about the swerve occurring later. A sliding deflected ball doesn't tend to come back until it starts to roll where a rolling deflected ball begins the return swerve sooner so the net effect is the rolling deflected ball ends up almost straight where the sliding ball may not have a chance to correct.
Again, squirt has nothing to do with the sliding phase of CB motion, and swerve occurs only while the CB is sliding. Once the CB stops sliding and is rolling, it moves in a straight line. The offset and angle of this line depends on both squirt and swerve. When the CB slides over a larger distance (with more speed and/or with backspin) it takes longer for the CB to complete it's sliding and swerve phase, and the squirt effect will be more noticeable since the CB moves out more before the swerve brings it back some (or a lot with added cue elevation). Therefore, in general, net CB deflection will be greater for fast-speed shots and for draw shots. For more info and demonstrations, see
net CB deflection speed effects.
The real question isn't so much a technical one for me. I just was looking to find out if it made sense that I needed less correction on a long hard hit force follow with spin than a long power draw with spin and it seems that is reasonable and not just my imagination.
You are correct. You need to adjust for net CB deflection more with fast speed and with draw shots. That's why FHE is more appropriate for slow, long, follow shots, and BHE is more appropriate for short or fast shots (especially with draw). For more info, see
backhand english (BHE) and front-hand english (FHE).
And yes I meant with side spin I am not sure you can achieve immediate forward roll. It does seem to slip off before rolling but that is not based on any scientific testing, just the way it appears.
Immediate roll is strictly possible only with a level cue (where there is no swerve) and with moderate amounts of sidespin, where the tip can strike the CB high enough. For more info, see:
natural roll, maximum offset, and overspin.
I hope that helps. Please look through the resources and videos if you haven't done so yet. They should answer most questions you or others might have.
Regards,
Dave
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