squirt robot results

[dr_dave]

endmass distribution

When you measure the pivot point you're measuring "endmass", but you're expressing it in inches (shorter pivot point = more endmass; longer pivot point = less endmass). I don't think "effective endmass" can be expressed by the amount of total mass in the first 7 inches of the shaft because it would most likely vary with the distribution of the mass too (a heavier ferrule on lighter wood would squirt more than a lighter ferrule on heavier wood even if they both have the same total mass in their first 7 inches).

Good summary. Diagram 4 in my February '08 BD article shows this effect quite clearly. When the added mass is closer to the tip, the squirt increase is dramatic. As the added mass is moved away from the tip it has less and less effect ... and no effect past about 7 inches.

Regards,
Dave

 

[dr_dave]

level cue = no swerve

His "squirt robot" uses a level cue so there is no swerve.

You can see the robot here (on the second page).

Exactly. Our machine was specifically designed to measure squirt only, by maintaining a perfectly level cue. If the cue is elevated (as with Predator's "Iron Willie" and Meucci's "Myth Deroyer"), swerve comes into play. Swerve depends on the amount of cue elevation, amount of tip offset, shot speed, and ball/cloth conditions. So with an elevated cue, it is difficult to get consistent and accurate squirt (and cue "natural pivot point") readings. Meucci also uses an object ball. This also brings throw into the equation. Throw varies with speed, amount of English, cut angle, amount of forward roll, and ball conditions (see my August '06 through July '07 BD articles).

To compare cues, it is best to measure squirt alone, by using a level cue and no object ball. Otherwise, the measurements are affected by everything mentioned above.

Regards,
Dave

 

[dr_dave]

effect of bridge length

I have heard people ascribing bridge length to squirt, usually referring to long bridges as reducing squirt.

It would seem simple enough to adjust this experiment to change the bridge length with the same shaft and chart the results.

I will add this to our list of things to test. The machine bridge is much stiffer than a human bridge, so the effect (if there is one) should show up clearly. Unfortunately, our machine needs bridge length to generate speed (just like humans), so the tests will have less speed at shorter bridges.

I haven't tested this, but I wouldn't think a hand bridge could have much effect on a cue's squirt, unless the bridge length were very short and the bridge were very firm and stiff (e.g., bony hand with tight, closed bridge).

Regards,
Dave

 

[CueAndMe]

Swerve depends on the amount of cue elevation, amount of tip offset, shot speed, and ball/cloth conditions.[/URL]).

So if cue elevation can be eliminated would tip offset, shot speed, and ball/cloth conditions become non-issues?
If so, would striking the cueball high, to create a horizontal cue, eliminate these issues as well?

 

[dr_dave]

cue elevation for follow shots

So if cue elevation can be eliminated would tip offset, shot speed, and ball/cloth conditions become non-issues?
If so, would striking the cueball high, to create a horizontal cue, eliminate these issues as well?

The closer the cue is to level, the less a shot with English will swerve. Unfortunately, because of the height of the rails, the diameter of the cue (above the rail), and clearance between the cue and rail, the cue will not be level on most pool shots. Also, if you hit above center with English, the squirt direction is down a little; so even with a level cue, an above-center hit still results in slight swerve action (because the effective impact direction is still down a little).

Having said all of this, an above center hit can reduce cue elevation and reduce the effects of shot speed and ball/cloth conditions (i.e., there will be less swerve).

Regards,
Dave

 

[klockdoc]

The closer the cue is to level, the less a shot with English will swerve. Unfortunately, because of the height of the rails, the diameter of the cue (above the rail), and clearance between the cue and rail, the cue will not be level on most pool shots. Also, if you hit above center with English, the squirt direction is down a little; so even with a level cue, an above-center hit still results in slight swerve action (because the effective impact direction is still down a little).

Having said all of this, an above center hit can reduce cue elevation and reduce the effects of shot speed and ball/cloth conditions (i.e., there will be less swerve).

Regards,
Dave

Question: I was answering a post the other day and I mentioned that while testing an OB-1 shaft, i aimed exactly as I would with my normal cue and made all the shots I tried. This past weekend, I also tested a Predator and STILL did not notice a meaningful difference between my cue.

This weekend, I placed a ball on the foot rail frozen to the middle diamond and using a stripe on the spot, shot at the ball in two different methods.

1). using center left english, medium stroke, the stripe hit the ball on the rail directly in the center. The tip splitting the stripe.

2) using follow left english, medium stroke, the stripe hit the left quarter of the ball on the rail.

I also let a friend of mine try this shot also to make sure I was not unconsciously correcting for this shot and his results ended up the same.

I also noticed that I came into this shot with left center english. I did not come into the shot center and then adjust to the left. I think Joe T mentioned this as an undesirable method. However, it did not seem to affect my shot.

Now this is a normal shaft for this cue. Is this what you would consider a low-deflection shaft?

Or, would additional tests need to be performed?

 

[JoeyA]

FYI, my February '08 BD article shows a bunch of interesting results from a squirt-testing machine some students and I designed and built recently. The article contains illustrations and graphs showing data for:

- how squirt varies (or doesn't vary) with speed.

- how squirt varies (or doesn't vary) with twist angle of a laminated shaft.

- how squirt varies as end-mass of different amounts is added at different distances from the tip.

Please check out the article and let me know if you have any feedback, comments, or questions.

Dave

A little REP for you, Dr. Dave!

Those students who wish to get an even better look at how to improve their game can order any one of Dr. Dave's pool instruction products:

I believe he has a couple of different products and services (books, DVD, CD, and even a pool school etc.)

Dr Dave is so polite that he doesn't even put his advertisement in his posts but I will.

http://dr-dave-billiards.com/

If the only thing you EVER learn from him is the 30 degree rule, it will make you a better player. (just don't tell the GINGERBREAD MAN).

JoeyA

 

[JoeyA]

Question: I was answering a post the other day and I mentioned that while testing an OB-1 shaft, i aimed exactly as I would with my normal cue and made all the shots I tried. This past weekend, I also tested a Predator and STILL did not notice a meaningful difference between my cue.

This weekend, I placed a ball on the foot rail frozen to the middle diamond and using a stripe on the spot, shot at the ball in two different methods.

1). using center left english, medium stroke, the stripe hit the ball on the rail directly in the center. The tip splitting the stripe.

2) using follow left english, medium stroke, the stripe hit the left quarter of the ball on the rail.

I also let a friend of mine try this shot also to make sure I was not unconsciously correcting for this shot and his results ended up the same.

I also noticed that I came into this shot with left center english. I did not come into the shot center and then adjust to the left. I think Joe T mentioned this as an undesirable method. However, it did not seem to affect my shot.

Now this is a normal shaft for this cue. Is this what you would consider a low-deflection shaft?

Or, would additional tests need to be performed?

Perhaps YOUR cue is a low deflection shaft?
By any chance, is your regular maple cue shaft a narrow diameter shaft? (under 12.5 mm)

JoeyA

 

[Patrick Johnson]

Question: I was answering a post the other day and I mentioned that while testing an OB-1 shaft, i aimed exactly as I would with my normal cue and made all the shots I tried. This past weekend, I also tested a Predator and STILL did not notice a meaningful difference between my cue.

Since the OB-1 and Predator shafts are both low-squirt, it's not surprising that they'd perform pretty much the same, but it's hard to say how they should compare to your normal cue without knowing what kind of shaft it has.

This weekend, I placed a ball on the foot rail frozen to the middle diamond and using a stripe on the spot, shot at the ball in two different methods.

What does "shot at the ball" mean? What was the intended path of the "stripe on the spot"?

1). using center left english, medium stroke, the stripe hit the ball on the rail directly in the center. The tip splitting the stripe.

What do the blue phrases above mean?

2) using follow left english, medium stroke, the stripe hit the left quarter of the ball on the rail.

What does the blue phrase above mean?

I also let a friend of mine try this shot also to make sure I was not unconsciously correcting for this shot and his results ended up the same.

I also noticed that I came into this shot with left center english. I did not come into the shot center and then adjust to the left. I think Joe T mentioned this as an undesirable method. However, it did not seem to affect my shot.

What does the blue phrase above mean?

Now this is a normal shaft for this cue. Is this what you would consider a low-deflection shaft?

Or, would additional tests need to be performed?

What does the blue phrase above mean?

It's pretty hard for me to understand what you're saying and asking.

pj
chgo

 

[klockdoc]

Perhaps YOUR cue is a low deflection shaft?
By any chance, is your regular maple cue shaft a narrow diameter shaft? (under 12.5 mm)

JoeyA

Patrick originally suggested this. I do not believe so, it is the original shaft that came with the cue. Cue is dated back in the mid 90's. Tim Scruggs

Cue diameter is 12.75

 

[dr_dave]

low-squirt cues

If your shaft hits with as little squirt as an OB-1 or a Predator, then I think it is safe to say it is a low-squirt shaft (assuming your comparison shots were the same in every way: same speed, same tip offset based on tip shape, same line of aim with cue, etc.).

FYI, my December '07 article discusses low-squirt cues and how they compare to regular-squirt cues and whether or not they are helpful. Check it out. I also have a good summary of potential disadvantages of low-squirt cues here:
http://billiards.colostate.edu/threads/cue.html#low_squirt

Regards,
Dave

Question: I was answering a post the other day and I mentioned that while testing an OB-1 shaft, i aimed exactly as I would with my normal cue and made all the shots I tried. This past weekend, I also tested a Predator and STILL did not notice a meaningful difference between my cue.

This weekend, I placed a ball on the foot rail frozen to the middle diamond and using a stripe on the spot, shot at the ball in two different methods.

1). using center left english, medium stroke, the stripe hit the ball on the rail directly in the center. The tip splitting the stripe.

2) using follow left english, medium stroke, the stripe hit the left quarter of the ball on the rail.

I also let a friend of mine try this shot also to make sure I was not unconsciously correcting for this shot and his results ended up the same.

I also noticed that I came into this shot with left center english. I did not come into the shot center and then adjust to the left. I think Joe T mentioned this as an undesirable method. However, it did not seem to affect my shot.

Now this is a normal shaft for this cue. Is this what you would consider a low-deflection shaft?

Or, would additional tests need to be performed?

 

[CueAndMe]

Style of Play

If you were to develop a style of play that uses the current knowledge of squirt, swerve, tip offset, pivot point, elevation, back hand english, front hand english, back foot swahili, etc. what would it look like?

In other words, by style of play, can you effectively apply the positives or effectively cancel the negatives of factors like squirt, swerve, and english?

And what attributes should your cue have to match this style?

 

[Patrick Johnson]

If you were to develop a style of play that uses the current knowledge of squirt, swerve, tip offset, pivot point, elevation, back hand english, front hand english, back foot swahili, etc. what would it look like?

In other words, by style of play, can you effectively apply the positives or effectively cancel the negatives of factors like squirt, swerve, and english?

And what attributes should your cue have to match this style?

I'd use a low squirt cue and play as close to vertical centerball as possible. In other words, what everybody's been saying since leather tips invented spin (except for the low squirt stuff).

pj
chgo

 

[dr_dave]

style of play

If you were to develop a style of play that uses the current knowledge of squirt, swerve, tip offset, pivot point, elevation, back hand english, front hand english, back foot swahili, etc. what would it look like?

In other words, by style of play, can you effectively apply the positives or effectively cancel the negatives of factors like squirt, swerve, and english?

And what attributes should your cue have to match this style?

There is no sliver-bullet "style of play" that can magically solve all of the "challenges" associate with compensating one's aim for squirt, throw, and swerve. The BHE and FHE aim-and-pivot methods (see my November '07 article) can be used to adjust for squirt (and in some cases the combination of squirt, swerve and/or throw), but swerve and throw vary too much with shot speed, shot distance, cue elevation, type and amount of English, amount of forward roll, ball and cloth conditions, etc.). I think the best you can do is be knowledgeable of all of the effects (e.g., see my March '08 article summarizing squirt and swerve effects and my June '07 article summarizing throw effects) and/or have solid intuition based on many years of successful practice and play. There is no magical "style of play" that can solve all of the world's problems. Pool is hard.

Regards,
Dave

 

[CueAndMe]

<Snip>
Pool is hard.

Eloquent. Agreed.
Thanks