BHE and low deflection shafts

[Jal]

Have you watched some of Joe Tucker's laser trainer videos?

http://www.youtube.com/watch?v=hwVBh73s9js&feature=PlayList&p=80C27B389E4BF9A1&index=5

With his laser gadget he can be certain of aim and then he uses BHE on some straight in shots. The cb stops dead inline and spins in place. He doesnt say what shaft he is using. It was his videos that got me thinking about BHE and pivot point again. When I have tried it with my predator shaft...BHE doesnt seem to work like Joe's video. If the cb stops and spins in place, the ob misses the pocket. If I hit the pocket I get some cb side drift. Of course it could be my aim inconsistency? With the laser trainer, it looks like the cue is just slding in a groove...ie there really isnt a pivot "point" like a hand bridge would have. Does that effect the results also?

I'm on dialup and it's a rather long video, so I only looked at the first two minutes (my system hung up when trying to replay that too). It's hard to tell exactly what his pre-pivoting line of aim was, and just how well the object ball was following it after he pivots and shoots - the distances shown in the video don't allow any accurate gauging of these.

What your saying about missing the pocket when the CB has no side drift may go along with what I was saying, but it depends on which side the cueball was drifting toward! It should move over to the side the english was applied.

If he was able to pivot accurately about the pivot point of his cue, then his grooved block shouldn't have affected the results.

By wetting the contact point, I mean applying saliva or water to lubricate the contact area. This should get rid of most of the friction (throw). You could test this by freezing two wetted object balls together, or better, leave a small gap of 1mm or so, and then shoot them from an angle as a dead combo to see how far the second ball is thrown off line. The saliva works well enough on a proposition shot where the frozen balls are against a cushion.

If you do the aim-and-pivot test as I suggested, it's best not to simply shoot for a pocket - there's too much slop there. Aim for a point on the far rail before pivoting and adjust your pivot location until the object ball hits that point. That will be your cue's intrinsic pivot point, if you've reduced throw to essentially zero. The cueball and object ball shouldn't be more than about a diamond apart in order to minimize swerve. Too close though, and you reduce the accuracy of the test.

Jim

 

[Jaden]

I'm on dialup and it's a rather long video, so I only looked at the first two minutes (my system hung up when trying to replay that too). It's hard to tell exactly what his pre-pivoting line of aim was, and just how well the object ball was following it after he pivots and shoots - the distances shown in the video don't allow any accurate gauging of these.

What your saying about missing the pocket when the CB has no side drift may go along with what I was saying, but it depends on which side the cueball was drifting toward! It should move over to the side the english was applied.

If he was able to pivot accurately about the pivot point of his cue, then his grooved block shouldn't have affected the results.

Jim

the pivot point is going to be based on where on the shaft the stabilizing force is applied because it goes to how much bow there is in the shaft. If you look at the wei table diagram I posted it shows how the bow of the shaft will cause the shaft to point towards the portion of greatest mass on the CB

That's why the block works in Joe's video. the front of the block is the stabilizing point and it should be at the same point of the natural pivot point of the shaft.

 

[NaturalEnglish]

I sent a private msg to Joe and ask him what shaft he is using in the video. No reply yet. I will post what he says when I get a reply.

 

[Jal]

the pivot point is going to be based on where on the shaft the stabilizing force is applied because it goes to how much bow there is in the shaft. If you look at the wei table diagram I posted it shows how the bow of the shaft will cause the shaft to point towards the portion of greatest mass on the CB

That's why the block works in Joe's video. the front of the block is the stabilizing point and it should be at the same point of the natural pivot point of the shaft.

Jaden, I meant to comment on your diagram. I fear that it's not what's generally accepted as taking place, though it's an interesting alternative. It's usually imagined that the shaft bends in the other direction: to the left for left english; to the right for right english. I think the high-speed videos support this.

If, for instance, you were applying left english and the shaft was bowing to the right, the force acting on cue at the tip would have to be pointing a little to the right. Otherwise the cue wouldn't bend in that direction. The cueball would experience the same force, though in the opposite direction (action/reaction), and would be propelled to the left of the aiming line. You would get, in effect, negative squirt.

That's the orthodox view, but you're welcome to topple it if you can.

Edit: But we're talking about the overall average direction of the force here. I wouldn't be surprised, in fact it seems almost necessary (to me), that what your describing does take place at the beginning of impact. This might/should contribute an element of negative squirt, until ball rotation takes over and changes the direction of the initial force.


Jim

 

[JimS]

Colin's video marks the first time I have understood BHE and I think I've found something that will make a marked difference in my game.

I experimented with my cues for long enough today to experience a significant back ache. The two of my Sailor cues that I tested both have pivot points around 11" or 12" and this is also the point where all 3 of my South West cues that are available have their pivot points. My Varney cue has it's pivot point at about 8" or 9". My Predator SP w/314 shaft does not appear to have a pivot point. I went as far back as I could, over 22", and could not find a pivot point that worked. It shot straight w/max parallel english.

The Sailor cue is my playing cue and I think my game just went up a ball... or so my experiments would make me think/hope.

 

[whitey2]

That's funny...

[...]My Predator SP w/314 shaft does not appear to have a pivot point. I went as far back as I could, over 22", and could not find a pivot point that worked. It shot straight w/max parallel english.[...]

That's a little funny to me that you can't find a (the) pivot point. When you fool with mother
nature, strange things happen.

I have some theories that might explain what is going on, but I'm very busy at the moment. In the
meantime, I don't want to get too far off the topic, but this is relevant. Try some front hand
english for a little while, and I think you will be very surprised at what you find.

 

[Jal]

... My Predator SP w/314 shaft does not appear to have a pivot point. I went as far back as I could, over 22", and could not find a pivot point that worked. It shot straight w/max parallel english...

Very interesting - you're in good company. But could you provide some details as to your testing procedure? For instance, how did you judge a full hit on the object ball?

Jim

 

[Caromsoft]

My Predator SP w/314 shaft does not appear to have a pivot point. I went as far back as I could, over 22", and could not find a pivot point that worked. It shot straight w/max parallel english.

I was under the impression that the whole point of low deflection shafts like the Predator or OB-1 was that you could use parallel english instead of BHE, therefore not having to worry as much about the pivot point. Am I mistaken?

 

[JimS]

Very interesting - you're in good company. But could you provide some details as to your testing procedure? For instance, how did you judge a full hit on the object ball?

Jim

I'm not an experienced or scientific tester Jim. I just shot straight in shots, table length, shooting fairly hard with the intent to negate throw, on my 9 ft Diamond Pro w/tight pockets and tried moving the pivot point until the ball went in and left the cb spinning. If the straight in shot went in I tried it another 3 or 4 times to see if I got the same results.

I could not make a ball shooting with BHE and the Predator (unitl I went to parrallel english). This is what I expected after reading previous posts.

I can't figure out why the cb slides to the side after impact w/the ob. It seems to me I must be hitting the ob off center but repeated tries makes me believe that my aim is true.

Is there anything you'd like me to try with the Predator? I'll be glad to help if I can.

Edit: I thought that shooting pretty hard would possibly negate throw but that has not proven to be the case.

I'm having to line up so that a straight line through the cb/ob would end just outside the tip of the pocket facing, then shoot fairly hard straight into that spot on the cushion using heavy BHE w/stun. The shot throws in and the cb moves to the left about 4" to 6" while spinning madly.

I'm no expert but I believe my stroke is pretty straight while doing this test as I can shoot table length, head spot to foot spot, and the cb will come back off the bottom rail over the foot spot and back to hit the tip about 7 times out of ten. Therefore I feel pretty sure that I am hitting the ob full on and straight into the bottom rail aiming just outside the facing.

 

[PKM]

Just out of curiosity, do you know of any books that discuss BHE? Although my library is not comprehensive, I've never seen it before in print.

 

[Gutz]

bridge hand pivot

I've never tried using BHE, I've been moving my bridge hand. First I line up the shot without as if I just wanted to make the ball then I move my bridge hand to apply the enlish I want. Seems to work for me...I'll have to experiment with BHE....

 

[Jal]

I was under the impression that the whole point of low deflection shafts like the Predator or OB-1 was that you could use parallel english instead of BHE, therefore not having to worry as much about the pivot point. Am I mistaken?

That's the ideal. But Predator's own test results, along with Platinum Billiards', indicate that they fall well short of this. Others find that they don't?

Jim

 

[Jal]

I'm not an experienced or scientific tester Jim. I just shot straight in shots, table length, shooting fairly hard with the intent to negate throw, on my 9 ft Diamond Pro w/tight pockets and tried moving the pivot point until the ball went in and left the cb spinning. If the straight in shot went in I tried it another 3 or 4 times to see if I got the same results.

Thanks Jim. I appreciate this and your additional descriptions below.

I could not make a ball shooting with BHE and the Predator (unitl I went to parrallel english). This is what I expected after reading previous posts.

To be refered to later

I can't figure out why the cb slides to the side after impact w/the ob. It seems to me I must be hitting the ob off center but repeated tries makes me believe that my aim is true.

If the cueball is drifting off to the same side you're applying english, this is consistent with hitting the OB square. Throw acts equally but opposite on the cueball, which should account for roughly an inch of sideways travel. Post-impact swerve should account for the rest (you mentioned 4-6"). I don't know if using the word "swerve" sounds a little strange in this context, but it's there just as with a normal shot with english, ie, the cueball's spin axis is not perfectly vertical before or after impact, and this causes a rubbing action on the cloth. The cueball then moves in the direction of the friction.

But, if it's moving to the opposite side of the applied english, then you would have to be hitting the OB off center.

Is there anything you'd like me to try with the Predator? I'll be glad to help if I can.

I'm hesitant to ask because there's nothing in it for you other then satisfying whatever curiousity you may have about it. But if you ever have the desire, perhaps you could do what I described in the second to the last paragraph in my earlier post (#18).

If you did do the test, it would help to know just how much the friction was reduced by wetting the contact area. This could be checked by using two nearly frozen balls (just about 1mm or 1/32" apart), which are lined up to hit some point on an end cushion, then hitting the first ball firmly and full at about a 45 degree angle and measuring how far away from that point on the cushion the second ball is thrown (ideally none).

When performing the aim-and-pivot test, the cueball and OB should be about a diamond or maybe a diamond and a half apart, and hit pretty hard.

I would be very interested in the results, but expect nothing and thank you sincerely for the offer.

I'm having to line up so that a straight line through the cb/ob would end just outside the tip of the pocket facing, then shoot fairly hard straight into that spot on the cushion using heavy BHE w/stun. The shot throws in and the cb moves to the left about 4" to 6" while spinning madly.

If I may inquire further, were you using backhand or parallel english here? You indicated earlier that the shot wasn't going in with BHE. Also, what kind of english, left or right?

Jim

 

[Jal]

Just out of curiosity, do you know of any books that discuss BHE? Although my library is not comprehensive, I've never seen it before in print.

If you know what squirt is, especially the related concept of 'pivot point', then you'll know how to exploit it, which is what backhand english does. Bob Jewett has at least these three articles on squirt:

http://www.sfbilliards.com/articles/2002-08.pdf

http://www.sfbilliards.com/articles/2002-09.pdf

http://www.sfbilliards.com/articles/2002-10.pdf

You'll find extensive discussions of BHE by searching this forum (and others), particularly by Colin (Colenso).

Ron Shepard's paper (the physics of it) is here:

http://www.sfbilliards.com/Shepard_squirt.pdf

which is summarized here:

http://www.sfbilliards.com/sqrt.htm

I can't recall any discussion of BHE per se in books, but that may be my memory or limited reading.

Jim

 

[whitey2]

In case you missed this...

[...]Try some front hand
english for a little while, and I think you will be very surprised at what you find.

In an earlier post I suggested trying out front hand english (moving the bridge hand) with
the Predator, and I noticed you did not mention it in your later post. So, I was wondering
if you missed it, or are just ignoring it. I would be interested to know how a few shots with
FHE work out. But if your current testing methods result in the impression of parallel
english working completely, I suspect there is too much leeway in the tests. All I can
suggest is make the shot longer, and perhaps temporarily reduce the pocket width.

 

[JimS]

In an earlier post I suggested trying out front hand english (moving the bridge hand) with
the Predator, and I noticed you did not mention it in your later post. So, I was wondering
if you missed it, or are just ignoring it. I would be interested to know how a few shots with
FHE work out. But if your current testing methods result in the impression of parallel
english working completely, I suspect there is too much leeway in the tests. All I can
suggest is make the shot longer, and perhaps temporarily reduce the pocket width.

I thought that front hand english is the same as parallel english. Maybe not? I don't really know. By parallel english I mean that I line up the shot with the cue parallel to the aim line of the cb and I'm pretty sure that's the same as what you mean by front hand english. Sorry if I ignored your post/question. It was not my intent.

 

[JimS]

I put an object ball on the head spot and put another about 1mm away from it and lined up as best I possibly could (with wife on at the foot rail trying to help me line things up) to be aimed at the foot spot.

Shooting at about a 45 degree angle from the right side, with dry ob's, the ball on the spot was thrown about 1 ball width to the left of the bottom diamond, on each of 4 attempts.

After wetting the contact points with saliva on both ob's I got a result that really puzzles me. The ob contacted the foot rail about 1 ball width (or a little less than a ball width) to the other side/the right side of the middle diamond on the foot rail. Negative throw (??); for lack of a better term. What happened? The aim was not off, I checked that VERY carefuly and was backed up by the wife observing from the foot rail. I'm at a loss.

I'll try shooting BHE w/the Predator and a wetted contact point later today. I have to get going now.. promised I'd be at the AA meeting this morning.

 

[Colin Colenso]

Hi Colin. With regard to how squirt varies with shot speed, there is a post by Steve Titus of Platinum Billiards here, (see about 8/10'ths of the way down the page). He says that there is an increase of 0.2-0.3% per mile per hour over the range of shot speeds from 9 to 21 mph. This sounds believable to me, because after diddling with the numbers myself, I got an increase of about 0.75-1.0% per mph (they're in the ballpark anyway, and my theory was barebones). More importantly, Ron Shepard also concludes in his paper that there should only be a minor dependency on speed. I think this is backed up by an intuitive consideration of what goes on during impact, but I won't go into that now.

I recall reading Steve's article before. It is interesting stuff.

From Ron Shepard's paper I have to say that I disagreed with the conclusions. The main problem was that it relies entirely on the rotation/deflection mechanism as the sole cause of squirt. ( i.e. As the CB tries to rotate due to the spin, it much push against the tip that is spinning it such that with right english, the CB pushes the tip to the right, and hence bounces off slightly to the left...squirting ).

If this was the only mechanism for squirt, then speed maybe shouldn't come into it. That's why I proposed the 'partial tip slipping' mechanism as a minor but significant contributor to squirt.

As far as the location of the pivot point, his theory also shows only a minor dependency on tip offset. It moves slightly farther from the tip with increasing offset (english). In his example, for a ball/endmass ratio of 40, it goes from 19" at an offset (b/R) of 1/4, to 21.5" at an offset (b/R) of 1/2. Of course, I know you think there might be more going on then the endmass theory incorporates, but there it is.

I'd also think the offset plays a relatively insignificant role, which really is the beauty of BHE. btw: I still think that end-mass plays the major role, just not convinced it is the only thing at play.

It's crazy isn't it! But at least it makes for a good mystery.

I can see some potential problems with the aim-and-pivot test if people judge there to be a full hit when the cueball stops dead and spins in place. Because of throw, and even more so from post-impact swerve, I believe the cueball should move something like 4" over to the side after impact (depending on speed, offset and cue elevation of course). But from the numbers I get, this is not enough to explain the gross discrepancy?

I did originally think that these long pivot points were due to misinterpreting the role of throw, but some calculations I did showed me such innacuracies shouldn't change pivot point estimation by more than a few inches.

The only explanation I can offer is that they are perhaps playing the shots too slowly such that swerve in addition to the throw, it giving the appearance of much longer pivot points.

They do appear to use a different testing method than I do by playing the CB onto an OB that is not too far away and tracking the OB.

I just aim at points or balls several feet away. What I do know for sure is that pivoting at over 20" with a predator on a very firm shot with BHE will send the CB about 1/2" wide of the target contact point on the OB, over 4 feet of travel. In other words, not even close. But if I play the same shot at slow speed, the swerve will make it pretty close.

Platinum's robot has, well, a robotic-like grip on the cue (at least it did at one time), which can increase the mass that the cueball "sees". But I don't think this offers any real explanation for their numbers if the 30-50" crowd is right.

If I had a Predator shaft, I would use aim-and-pivot with a wetted contact point on the object ball to all but eliminate throw, and pay zero attention to what the cueball does after impact. The criteria for a full hit would be having the object ball go straight, and nothing else. But alas, I don't.

Perhaps your collaberation with Dr. Dave, if that's still in the works, will take on this conundrum. It is interesting, isn't it.

Jim

Yes Jim, it's still in the works. Unfortunately I still don't have anywhere to set up my table in Australia yet. Once I do, I can start with some more detailed testing and filming.

The goal is to provide charts and video instruction so that players can learn to play all shots with BHE taking into account the amount of throw for each shot. Naturally, a large part of that will be the discussion of determining the appropriate pivot point for different shots.

Colin

 

[JimS]

I used the Predator w/BHE. I placed a wetted ob on the center spot and the cb on the head spot. I used a minimum of 2 tips of BHE w/the Predator, hitting firm speed (in trail shots the cb traveled to the end rail, head rail, end rail and back to center table = 3.25 table lengths) and a pivot point of 12". After 12 shots the most usual action was for the ob to hit the end rail from 1/2 to 1 ball to the right of the bottom rail diamond.

I also hit several shots w/parallel english with the most common result being the ob hitting the bottom rail about 3/4 to 1 ball widths to the right of the center diamond

For the sake of comparison: I then hit the same shot w/a dry ob and the result was hitting the bottom rail about 2 to 3 ball widths right of the center foot diamond usually banking the ball into the head right pocket, sometimes just to the short rail side of the pocket and sometimes hitting the long rail coming in. It was hard to see exactly where on the bottom rail the ob was hitting (wife not available for this test) but the most common result was for the ob to hit the front short rail about 1 to 1.5 ball widths short of banking into pocket. I think this equated to hitting the bottom rail about 2 ball widths to the right of the center diamond.

I'm learning that throw makes significantly more difference than I'd imagined. Now that I know how to use BHE w/my playing cue I've been practicing to see how much throw affects my attempts to pot balls and I'm finding out why, on many occasions, I've been missing. I don't know where I got the idea but I had it in my head that throw only affected balls shot at very slow speeds. WRONG!

Went back to the table and hit about 40 shots w/my Sailor play cue using the above methods w/dry ob and BHE and the pivot point where I learned yesterday it should be. The ob most frequently impacted the bottom cushion about 1 ball width right of the center diamond.

 

[Jaden]

QUOTE=Jal]Jaden, I meant to comment on your diagram. I fear that it's not what's generally accepted as taking place, though it's an interesting alternative. It's usually imagined that the shaft bends in the other direction: to the left for left english; to the right for right english. I think the high-speed videos support this.

If, for instance, you were applying left english and the shaft was bowing to the right, the force acting on cue at the tip would have to be pointing a little to the right. Otherwise the cue wouldn't bend in that direction. The cueball would experience the same force, though in the opposite direction (action/reaction), and would be propelled to the left of the aiming line. You would get, in effect, negative squirt.

That's the orthodox view, but you're welcome to topple it if you can.

Edit: But we're talking about the overall average direction of the force here. I wouldn't be surprised, in fact it seems almost necessary (to me), that what your describing does take place at the beginning of impact. This might/should contribute an element of negative squirt, until ball rotation takes over and changes the direction of the initial force.


Jim[/QUOTE]

It would have to take place. attached is an image illustrating the forces and where they apply to the shaft and because of that, why it would have to bend in that direction


If you look at the drawing you will see thatthe blue line represents the center of mass of the CB and the straight red line represents the contact point on the tip and line of direction of force to the shaft.

The curved red line represents the parabolic(rough representation) curve of force from the point of majority of mass in the CB and the point of contact on the tip. That line of force should always cause initial bend to be to the opposite side of the line of force compared to center line throughout the time of contact. After contact doesn't matter.

Regardless of how it's described, the same thing is happening. The Cueball is going in the direction where the majority of mass directs it. If you line up on the centerline and stroke off center the center of mass of the CB is still pointing straight ahead forom the original aimline. There are some other things that have an effect on the direction i.e. swerve, etc. but those things in most cases are so minute in effect that adjustment for anything short of a super hard stroke or super slow stroke is negligable.

That's why when using spin to throw the ball into a pocket when you can't see enough of it is usually done at slow speeds.