OBs CURVE short on hard-hit banks

CreeDo said:
I'm still a little weirded out by pounded banks. The shortening of the angle seems stronger than can be explained by just a lack of natural roll (as compared to a 'regular' bank). I'd expect a sliding pounded ball to come off the rail close to the mirror angle, but it seems like it's coming off much tighter than the angle in. If that's not due to rail friction, what is it?
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I've been playing under the same assumption as you, Creedo. I've always felt like it was possible to shorten up banks much more than that mirror angle using only speed. By how far seems to vary with the playing conditions.

Another reason I say this is, the forward roll should have less - maybe even negligible - effect for banks that are closer to perpendicular to the rail. It still seems like you can shorten those up a considerable amount using only speed.

It should be fairly easy to test whether lack of forward roll is the only factor shortening up those banks. With the object ball close to the rail (but not touching, so as to eliminate as many variables as possible), there should be a range of shot speeds that will result in the object ball sliding into the rail. If the rebound angle changes with shot speed, then there's got to be another factor involved.

Maybe someone with the time to play around with it a little can help us out with the testing. I won't have a chance to look at it until this weekend.
 
The nose height of the rail may effect this a lot. To test this take a stripe ball and using it as a cue ball hit it straight in to a rail. Watch the rebound to see when it stops its original forward roll. If the rails are installed correctly it should be almost imediately. On some table or even some rails on a table the reverse spin does ot take effect for several feet.

This will of course effect the bank angle at higher speeds.
 
I always thought that the reason pounded banks went short was because of the OB basically being enveloped by the rail and then the ball is effectively spit perpendicularly out of the rail, thus negating some of the original incident angle.

It depends on how hard the rails are, softer ones make pounded banks go shorter and and harder rails don't allow as much effect.

I'm probably wrong, and Dave will link me the HSV that proves it. :)
 
Endymion said:
I always thought that the reason pounded banks went short was because of the OB basically being enveloped by the rail and then the ball is effectively spit perpendicularly out of the rail, thus negating some of the original incident angle.

It depends on how hard the rails are, softer ones make pounded banks go shorter and and harder rails don't allow as much effect.

I'm probably wrong, and Dave will link me the HSV that proves it. :)
Click to expand...
How about this one:


Regards,
Dave
 
Endymion said:
I would be interested in seeing a similar HSV demo but with tighter angles and no setup ball (it would get in the way anyway at the angles I'm interested in).
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Bob and I did some experiments with a stunned and rolling CB at many angles and various speeds. One of us will try to write up the results soon (I hope).

Regards,
Dave
 
Tennesseejoe said:
The nose height of the rail may effect this a lot. To test this take a stripe ball and using it as a cue ball hit it straight in to a rail. Watch the rebound to see when it stops its original forward roll. If the rails are installed correctly it should be almost imediately. On some table or even some rails on a table the reverse spin does ot take effect for several feet.

This will of course effect the bank angle at higher speeds.
Click to expand...

This is especially true with brand new cloth.

I recall that immediately after RKC installed 860 Simonis on my Pro Am, a ball hit to a rail slid back for a very substantial distance.., several feet before the forward roll started... I presume that this due to the low rolling CoF value for brand new cloth (no embedded chalk dust yet).
 
cigardave said:
This is especially true with brand new cloth.

I recall that immediately after RKC installed 860 Simonis on my Pro Am, a ball hit to a rail slid back for a very substantial distance.., several feet before the forward roll started... I presume that this due to the low rolling CoF value for brand new cloth (no embedded chalk dust yet).
Click to expand...

You are right---good observation.
 
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