# Contact time

#### pagaspoling

##### Member
I'm researching impact and which parameters that effect the cueball in the hit. We know that contact time is really small and changed by tip hardness and cue speed. Some people claim that you could change the contact time by timing the shot by applying a hit through the cueball. Barry Stark "proved" this in a video but as he didn't t measure tip offset, ball speed or cue speed there is no way to see what changed the contact time.

My question is: Let us say we hit a straight shot with 1/4 radius offset below center. We hit two shots where all the parameters are exactly the same except that we change the tip. One tip is very hard (95-100) and the other a super soft (55-60). As we are close to the center there should be no risk for a miscue. How will these two shots differ?

The only thing I get from the info i found is that the harder tip will create more cue ball speed. What I'm trying to understand is which shot, if any, will draw the furthest?

#### Patrick Johnson

##### Fish of the Day
Silver Member
I'm researching impact and which parameters that effect the cueball in the hit. We know that contact time is really small and changed by tip hardness and cue speed. Some people claim that you could change the contact time by timing the shot by applying a hit through the cueball. Barry Stark "proved" this in a video but as he didn't t measure tip offset, ball speed or cue speed there is no way to see what changed the contact time.

My question is: Let us say we hit a straight shot with 1/4 radius offset below center. We hit two shots where all the parameters are exactly the same except that we change the tip. One tip is very hard (95-100) and the other a super soft (55-60). As we are close to the center there should be no risk for a miscue. How will these two shots differ?

The only thing I get from the info i found is that the harder tip will create more cue ball speed. What I'm trying to understand is which shot, if any, will draw the furthest?
The harder tip will transfer more energy to the CB, so it will spin faster and move faster.

For a straight (no cut) shot the speed is all lost in the collision (CB stops), but the added spin remains and is reduced less by table friction because of the speed - so more draw.

pj
chgo

#### Bob Jewett

##### AZB Osmium Member
Staff member
Gold Member
Silver Member
...

The only thing I get from the info i found is that the harder tip will create more cue ball speed. What I'm trying to understand is which shot, if any, will draw the furthest?
I suppose it is possible that the softer tip will compress more and that will change the center of the tip-ball contact patch. I suppose that might be slightly closer to center hit or farther away, and maybe that would give more draw. I doubt that the effect is large enough to notice.

#### pagaspoling

##### Member
Thank you for the replies. To me it feels like the soft tip should draw more so when I was very surprised when i read this was not the case in one of the technical proofs on billiards.colostate.edu. I spent some more time thinking about it and think its probably because all the cues I've tried that has a phenolic tip is very stiff in them self. Also when you hit a ball with a phenolic tip the hit feels "harder" even though you use the same speed as with a soft tip.

Then what makes a cue spin more or less? Which properties of the cue affect the cue ball?

#### Bob Jewett

##### AZB Osmium Member
Staff member
Gold Member
Silver Member
... Then what makes a cue spin more or less? Which properties of the cue affect the cue ball?
If the cue is solidly built, the exact construction has almost no effect on how much spin you can get on the cue ball. The amount of spin (relative to the speed) is almost entirely determined by how far from center the tip contacts the cue ball.

#### garczar

##### AzB Silver Member
Silver Member
Thank you for the replies. To me it feels like the soft tip should draw more so when I was very surprised when i read this was not the case in one of the technical proofs on billiards.colostate.edu. I spent some more time thinking about it and think its probably because all the cues I've tried that has a phenolic tip is very stiff in them self. Also when you hit a ball with a phenolic tip the hit feels "harder" even though you use the same speed as with a soft tip.

Then what makes a cue spin more or less? Which properties of the cue affect the cue ball?
none

#### Patrick Johnson

##### Fish of the Day
Silver Member
...what makes a cue spin more or less? Which properties of the cue affect the cue ball?
More force (harder tip, stiffer/heavier cue or even faster stroke) puts more RPMs on the CB, but also more speed - so the spin-to-speed ratio (and therefore the effect of the spin) is unchanged.

Or, to put it another way...

pj
chgo

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#### pagaspoling

##### Member
I find this very disturbing, for 17 years now I've been trying to have good timing and tried hit the ball in different ways in order to get various reactions from the white ball and now I'm starting to realize that all that I need to do is to control impact location and speed.

So the reason I feel like I get more spin from a soft cue with a soft tip is that hit feels softer compared to a stiff cue with the same speed?
And this trick me to believe a hit the shot softer?

#### boogieman

##### It don't mean a thing if it ain't got that ping.
And this trick me to believe a hit the shot softer?
I am not an instructor, but in my opinion, yes. I love playing with a hard pressed tip. It forces me to shoot soft. I can also hear the hit when playing soft. Hearing for me is important. It's instant feedback. Don't believe me? Watch a group of pool player's reaction when a cue hits the floor or they hear a full table draw turn into a miscue.

#### WobblyStroke

##### Well-known member
I find this very disturbing, for 17 years now I've been trying to have good timing and tried hit the ball in different ways in order to get various reactions from the white ball and now I'm starting to realize that all that I need to do is to control impact location and speed.

So the reason I feel like I get more spin from a soft cue with a soft tip is that hit feels softer compared to a stiff cue with the same speed?
And this trick me to believe a hit the shot softer?
Ye there are two ways to vary draw distance.... same spot feeling out the speed, or same stroke and speed at different tip heights relative to centrerball. The latter requires less arm talent and should be easier to implement for most, esp under pressure.

Personally, I prefer the feel way and drawing with a soft hit while keeping pockets big more often than not. It has the added effect of giving a slight psychological edge over opponents who just don't have that shot in their arsenal. Seeing someone make shots/outs that they can't make has a way of at least planting seeds of doubt in opponents without the sturdiest mental games.

I love soft tips and the feeling of digging into a ball with one. I too erroneously believed they provide more spin in the past. Turns out I can do the same things with a hard tipped cue....I just don't like the feel/sound as much. Kamui Black Super Soft for me.

#### pagaspoling

##### Member
I too use soft tips and shoot a lot of my small draw and stop shots with full draw. On new cloth and tight pockets it really is the best solution the get the balls dropping. For me How soft is the best tip on the market. Used Kamui before but i think the quality got dropped, at least where I was getting them.

But then when players talk about different strokes in order to get different reactions its really just ways to create various speeds. So a stroke shot with elbow drop where you accelerate all the way to the ball is the best way to get a lot of speed. On roll shots where you have to stop precisely you can level off the pace through the CB. And then there is Jabs, Punch and Kill strokes with different acceleration profiles as well. But in the end is just ways to reach a certain speed at impact not about impact in itself.

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bbb

#### Pin

##### AzB Gold Member
Gold Member
The 'soft tip - more grip' argument is intuitively very appealing. And consider what people used before leather tips: just the wooden end of the cue, perhaps with a substance similar to chalk (people used to twist the tip of the cue into the ceiling). The introduction of the leather tip (and chalk) was a big leap to a softer tip and more grip.

But in terms of the practical difference between hard and soft tips, I defer to everyone who's already posted here.

I guess theory meets its limitations in practice