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[Neff]

Sorry for 3 new posts in one night.  I'm all pent up this week, I guess.

OK OK OK, I had an epiphany the other day about string length.  I've always thought, "the bigger the top, the longer the string."  And then I read somewhere, "the heavier the top, the longer the string" and that never set well with me.  For example, I've filled an Imperial with silly putty before and the optimum string length didn't seem to change even slightly.  I've come to the conclusion that neither statement is entirely correct.

A better way of saying it is, "The higher the center of mass, the longer the string, and versa vice-ah."  This is perhaps abundantly obvious to some folks (or perhaps it has been previously discussed), but for me it really cleared things up.  There are of course other factors; string thickness and the shape of the top for example, but this statement helps a bunch when you are comparing a modified top to an un-modified top of the same mold.

The Diet RC mod (yocephus' hole-in-cap of Rip Cord mod), and Pulp's posts about tip weight have let me to understand that when you lower the center of weight without changing the shape, it is essentially the same as chopping mass off the top, allowing you to shorten the string.  I've always wanted my RC string to be a little shorter, and if I made the string any fatter you wouldn't even be able to see it wirewalking because it would be going too fast.  By removing mass in the cap of a RC, adding weight rings in the normal spot and putting a bearing in the bottom, I can cut about 3 inches off my string!

Similarly, simply by using a Torpedo cap in my Hollow Dog instead of a Bulldog cap, I can add a couple of inches to the string, which I've always wanted a little longer.  Adding an o-ring in between the cap and the base raises the center of mass even more...

I should have pictures with this topic but I'm running out of steam this evening.  Just wanted to get it out there and see if other folks have had the same experience.

[Jeromy K.]

On the topic of string length. I think a guide of length for different tops would be good. I find it odd when I see a video of some one playing a top, they seem to have a much longer string than i use. I don't know just a thought.

[johnm]

Neff this is where you agree with Ta0 or Ta0 agrees with you or you both agree  (oh what's it matter you moderators are all the same---great!  )  Plus it has the bonus info of his string length for two tops.

That's probably way too short. With tops the string length depends on the top, not the player, contrary to yo-yos. It also depends on the thickness of the string: thinner string has to be longer, so if you want to shorten the string you can use thicker string. What really matters is how high the wrap reaches on the top body (i.e., it has to be lower than the center of mass but not too low).

On my YYJ tops I use the shortest string of my performance tops: 58". On the ripcord I have 66" of a thick-gauge string.

The comments about string thickness might explain Jeromy's observation about his string length verses others--its hard to judge string thickness from most of the videos.  An additional factor that may make string length a little more individual than just the top is the way people wind the string.  Tops without the cap ring allow you bind the knot in different places (from near the cap to near the final wrap) and string tension while winding can significantly change both the diameter and length which could result in a different position of the final wrap. 

[mtntop]

Now I used to have a different string for every top and I would even color code them with some tape. At some point I got tired of matching up my tops and strings or some were wearing out but someware along the line I realized I like to play with longer strings and just adjust the angle of my throw accordingly. I also run about four thicknesses thin for imperials and the Mexican trompos, regular for RC,BK,HP,and small spintastics, Thick for my QS and trompo grandes, Extra thick for for my larger hand made and watts tops and in all but the extra thick the are 62 to 66 inch long . Now I thought I remembered a post or tip someware that helped determine the length of string by how many wraps up the top I think it was 14 but i don't really recall most of mine are at 15-16 wraps I adjust my throw angle, No science here just personal preference

[poptop]

I believe Neffy is on to something--string theory baby!  I got my first hint of the lower center of gravity effect when I replaced my QS cap with the plastic cap.  Right away I found I needed to shorten up my string, which made sense as my top got lighter, but this same string seemed a bit too short for my lighter RC.  The HP demonstrated this as well; even though it is heavy, I was surprised how short a string I needed.

Ta0 has always maintained that the thinner the string, the longer it need be for a given top.  I have found this to be true (but don't really understand why?  Perhaps it's a gear:ratio thing?).  When I was just learning to throw heavier tops--like a stock QS--I found a much fatter string helped me a bunch.  I think fatter strings are a little more forgiving thus good for teaching kids to spin too.

As for preference, I'm starting to feel I like the light feel of thinner string.  Now that I've got a bit more control, I think I can "feel the top" better with thin string.  Right now, I'm trying to find the balance betwen something that will hold a bit of a loop (with delusions of whip catches...) and still have a light feel. (Unclephreak, are you listening?)

Another thing thinner string can do for you is slow down wire walker type tricks when the top is really spinning quickly--this has been useful for me when throwing small but heavy wood tops.  A longer string also seems to allow you to throw harder--even throw overhand--which has some special advantages to those looking to battle!

Mtntop mentioned adjusting the angle of your throw--this has been really important to me too.  It helps you quickly determine how to fine tune string length if you wish, or simply "correct" for length with the throw.  As a right-hander, I rotate my wrist/forearn clockwise to compensate for a shorter string (I think of this as the "weak throw"); if doing this straightens the top's landing or boomerang then a longer string will accomplish the same.  If you rotate the wrist/forearm counter-clockwise ("strong throw"), it will correct for a longer string: shortening the string will accomplish the same.  Clear as mud, right?

[Dizzy]

Here is a little something that encourages trying the technique mtntop uses.  It's at the very end:

http://www.topspinning.com/tricks/stringlength.ghtml

The author (does anybody know him?) also says that optimum string length is determined by the weight of the top but I think that Neff has gotten down to the bedrock of this idea with his discussion of a top's center of mass.
But I digress...

Once I am skilled in the fundamentals of top-spinning I will certainly start tinkering with my throw but for now I think I’ll be better served by limiting my variables.  For someone new to the hobby like me, I think that a really consistent boomerang throw is a key to early success and this is where muscle memory comes in.  Until two days ago the blizzard was the only bearing top I’d thrown.  It took me several days of experimenting with my technique when I first got it to feel comfortable and now I’m able to throw a consistent, fairly strong boomerang with it.  Then two days ago I got my Mexican trompos from ta0 and I had two new bearing tops to try out.  I found the 2nd-gen turbo-pro to be very easy to throw with my blizzard string without altering my throw at all.  When I switched over to the top-dog shaped 1st-gen turbo I had to go to a much shorter string to get the top to sit up without altering my throw.  For reference, my stock spintastics string is 58” from knot to knot and that’s what I use for the blizzard.  I need Dale’s string shortened to 52” to get the 1st gen turbo to sit up for me while keeping my throw consistent. 

All that said, I think that as a newbie I would benefit from knowing a top’s optimum string length if that is, in fact, a knowable thing.  With that in mind, here are a few questions:

1.   Is it possible to calculate a top’s optimum string length without also taking into consideration the thrower’s personal technique such as their preferred angle of throw or strength of throw?

2.   Is it possible to calculate a top’s optimum string length without also considering the string’s gauge?

3.   If you need your string longer  as it gets thinner might that have anything to do with how high up the top the string goes from the tip when wound?

4.   Are there any other factors that might influence a top’s optimum string length?

5.   Assuming that it's possible to esatablish an optimum string length, is it practical to attempt to do so considering the variables associated with each individual's throwing technique?

[Neff]

Dizzy -
This is Herman Lau:  http://www.topspinning.com/videos/Bungi%20Jump%20Snatch.mpg

He posted here recently, it was awesome.

I was going to try to answer your numbered questions in order, but they all sort of cross reference so I'll try to summarize it in this way:

IMO you've made a good decision to not monkey with your throw as you get started.  As you say, maintaining that variable helps you understand what different tops / strings do.  Later, when you find a length preference, you will know there are various ways to get the length you want. 

You touched on another variable you can lock down to make it easier, and that's (what I call) the wind line.  Instead of thinking "optimum string length"  think optimum "wind line"; meaning the point at which the string ends when wound around the top.  I think it may be possible to calculate where this line should be, but trial and error would get ya there quicker.  If somebody tinkered around with it, they might be able to at least find a good rule of thumb, like "halfway to the center of mass" or something.

Perhaps the best way to summarize would be in a scenario.  Let's say you have a top that you don't like how long the string has to be for a tip up throw / tip down return.  You may:
1) Go ahead and use a shorter string, and rotate your hand counter-clockwise as you release.
2) Use a thicker string, wind it up to the same wind line as before, since it is thicker it will take less string to get to the wind line, and thus be shorter.
3) Lower the center of mass of the top.  Easier said than done, but it's possible.
4) Reduce the diameter in the winding area.  Gonna need a lathe for that one, but a slimmer "cone" will need less string to reach the wind line.

As far as a length chart for the various tops, the string thickness variable makes that difficult, but it would be possible to make a list of ideal lengths using the string the top normally comes with.  I'm not gonna tackle that project any time soon, but throw a post up if a string or top is given ya problems.

[Dizzy]

Neff-

Thanks for pointing me towards Herman.  I had seen that video but never knew who it was.  It's good to have a face to put to the name. 

I'll let you know when I run into problems.  And I wouldn't worry about a string chart.  That sounds like way too much work for the payoff. 

[poptop]

Yeah, I think the string gauge variable makes it tough to come up with a standard length.  We could decide to work from a string that remains fairly constant, say a spintastics thin (probably not a perfectly uniform standard, but readily available and well known) and come up with a good starting point of reference. 

The thing that I've always wanted to see is a standardization of how we communicate string gauge.  There is a numeric notation for string, for example you often see hardware store "garden twine" or mason line in "#21". This roughly approximates the thickness of spintastics thin, but it is by no means consistent.  I suspect these numbers at one time (perhaps still do?) corresponded to the number of base threads in the cord, but these threads are variable in size as well.  FWIW, the number scale usually jumps by three for each change in string size.  This seems to fit our situation well as we typically use 3X string; every time an additional base strand is added, the total number of strands goes up by three.  I believe cord gauge is also communicated in mass per linear length, say grams per meter.  Simple string diameter is probably useful too, but difficult to measure as the string compresses and the differences between similar string sizes are slight.

It will be interesting to see if the wind line concept holds up, especially relative to center of mass.  I recall Ta0 showing us how to find center of mass by suspending tops with a string and a piece of tape.  Looks like it's time for some 'speriments...

[MatiasStuntMan]

I think there are too many variables making it impossible to find the string length formula. One thing that I have noticed, and this is another variable to consider, is that when the string starts to get older it doesn't elongate as much as when it is new having at the end a stiff and thinner string, and in the process one has to accommodate the angle of throw to compensate for this. Before Neff wonderful video on how to make strings I had a pile of thinned stiff strings (and greasy too), and every time I used a new one I had to tune up the angle of the throw again. So for me is more important to be able to fine tune my throw, as mtntop mention before, based on what I want to do, like a boomerang throw for the right hand is different than the boomerang throw for the left hand for example,  and not having to have a string for each type of trow.

But a good rule of thumb could be a "string thick enough that at 18 (?) wraps it wraps 2/5 (?) of the height of the top, from bottom to top". (I got this numbers using a Trompo Grande and its original string).

I don't have a Japanese Koma, but I am curios to see if this logic also applies for that type of top.

[Dizzy]

Matias-

I think you make some good points there.  There are so many variables.

I think that as I gain experience it will be easier for me to adapt my throw than to alter the string.

BTW, I recently picked up a Koma (I'm even newer to them than to a regular throw top), but I think that since the Koma doesn't have to right itself at the end of the throw, different string lengths may only make the Koma spin faster or slower.

But I could be wrong there.

[figs]

This is pretty interesting.  Personally I haven't noticed string length or thickness to be a major concern.  I do remember reading somewhere (probably on the old board) about the 18 wraps from tip measure.  I've kind of been going by that as a general rule and it seems to work as a loose guide.  Then again I've been told by other players that I use a really short string and they can't throw with it.  I've been using the same string with Trompo Grande, Bearing king, toycrafter tops and the Mexican tops i got from Tao and they all spin fine.  The only one that didnt's work was the mini-mini mexican top,  but I found that a yoyostring is about 18 wraps on that one and that works great. 

Go figure,  I'm not sure that this helps anything,  in fact it probably confuses things.  But I've noticed that getting a feel for the weight and balance of the top plays as much of a part as string length.  For me anyway.

[Java]

Chris' theory does explain why when I put a steel tip in a Sidewinder or a Ripcord without adding a weight ring/o-ring it becomes a heavier top that somehow seems to want a shorter string. The weight goes up, but the center of mass goes down. Hmmmm..........

Have Fun,
Java

[Dizzy]

Java-

I think what's going on here is that since the steel tip is heavier than the plastic tip, and since tips are located at the bottom of the top, and also because you are adding no counter-weight at the, ahem, top of the top, the heavier tip is moving the COM further down the top.  If you would have used a brass tip, which would be even heavier than steel, it would have magnified the effect even more.

On the other hand, if you would take the weight difference between the plastic and steel tips, and then evenly distribute that weight around the existing COM, nothing would change.

It's not simply adding weight that lowers the COM, it's where you put that new weight.

[Java]

Right, because you've added all the new weight right at the bottom of the top. (bottom of the top?  )

Have Fun,
Java