Russian ball observations
TK
one, two, and three spoonfuls of sand. The empty shells weight 10 g, a
spoonful is 30 g. That yielded balls with a total weight of 40, 70, and
100 g. The total capacity is almost exactly 8 spoonfuls. These weights
are for reference only, they are repeatable but not necessarily spot on
accuracy.
These are the characteristics I have observed for the sand fill:
40 g = outrageous wobble
70 g = noticeable wobble
100 g = barely discernible
Thinking that the volume of fill was the determining factor, and trying
for a lighter weight ball I filled some with crushed walnut shell. I
tried them with three and four spoonfuls neither being as stable as the
70 g sand fill balls.
After a couple of years of feeling sorry for myself, losing motivation
to practice after quitting performing and the closing of my practice
space, I found a new practice space. It is a gym with high overhead
lighting. What little practice I was doing was at home on a carpeted
floor, rolling was not a problem. The balls sometimes roll tremendous
distances on the gym hardwood floor. The lighting is good enough that I
noticed that when a ball rolls it has split the sand onto the rotational
axis of the ball. I have not seen, but suspect that this happens when
the seam of the ball lands on the floor splitting the sand into equal
parts. If the seam is off center the ball rolls in a spiral if at all.
Curious as to others observations.
--
TK ~ aka Terry Kimpling
http://wejuggle2.com/circusskills.php learn/make juggle/balance equipment
Unless you are the lead dog, the view never changes.
..maks
I think I have some hand-made Russians at home made from 65mm playpit
balls from Toys'r us. I brought 100 for about �10 and after a month I
thought that they were a bit of a waste of money.
Anything under 90g or so seems a bit too light. And if the ball is more
then half full it kind of become more and more like a plain stage ball. I
found these were just too small to make a decent russian. In the end I
thought that getting cheap russians is mmore effort then it's worth and
brought the SRX-russians (both sizes , eventually)
--
----== posted via www.jugglingdb.com ==----
Boppo
> Unless you are the lead dog, the view never changes.
If a ball is significantly less than half full, then a fast roll will
throw the filling to the walls where it will be more or less rigidly
held, allowing the ball on a smooth surface to roll long distances.
But as the ball gets more filled, even with fast rotation there will
be some filling near the center of the ball where the centrifugal
force is less strong, and filling will fall across the middle (like
clothes in a dryer) as the ball rolls, dissipating energy and
arresting the roll. So in terms of roll resistance balls of the same
total weight but different filler density are not equal. But optimum
roll resistance is not necessarily optimum in terms of ball feel from
a juggling standpoint. There's probably no magic recipe, which would
vary with one's taste anyway. I just wanted to point out the
centrifugal force thing.
Filling a ball with a liquid is a whole different story, for the same
reason that raw eggs don't spin much at all. The popularity of liquid-
filled Russians is unsurprising. The same density-based arguments
apply, although (excluding mercury) the range of available densities
isn't as great as is available with solid granules.
-boppo
dpawson
I made were 65mm/2.5" and filled with salt. I settled on a weight of 80g,
and at that weight I find the wobble just about non-existent.
This weekend I made my first set of 3" russian balls (I suspect they're
actually 3.125" or something like that). Those I filled with sand; when
russians get dimpled due to air pressure, it can be relieved with a small
hole poked in the ball, but with salt inside it will leak unless the hole
is *really* small. The bigger balls are definitely more touchy. The first
set I made was at 90g, the second set at 100g. And even at 100g, they are
way more wobbly than the 80g 2.5in balls. If they ever collide in the air
at all, all hell breaks loose; both balls wobble wildly. All of which
makes me even more amazed that David Ferman does what he does with 3"
balls at 60g.
Dave
--
David Ferman
>
> I think my experience more or less echoes yours. The first set of russians
> I made were 65mm/2.5" and filled with salt. I settled on a weight of 80g,
> and at that weight I find the wobble just about non-existent.
>
> This weekend I made my first set of 3" russian balls (I suspect they're
> actually 3.125" or something like that). Those I filled with sand; when
> russians get dimpled due to air pressure, it can be relieved with a small
> hole poked in the ball, but with salt inside it will leak unless the hole
> is *really* small. The bigger balls are definitely more touchy. The first
> set I made was at 90g, the second set at 100g. And even at 100g, they are
> way more wobbly than the 80g 2.5in balls. If they ever collide in the air
> at all, all hell breaks loose; both balls wobble wildly. All of which
> makes me even more amazed that David Ferman does what he does with 3"
> balls at 60g.
>
> Dave
>
I don't see any wobbling in mine at all though. I hate wobbly Russians.
The texture of the sand has a MUCH bigger impact on how much the ball
wobbles than the weight.
dpawson
>
> I don't see any wobbling in mine at all though. I hate wobbly Russians.
> The texture of the sand has a MUCH bigger impact on how much the ball
> wobbles than the weight.
>
>
least part of the difference is that you're a hell of a juggler :-) But
you do raise a good point. I was quick to assume the difference was due to
the size and weight, when it wasn't exactly a controlled experiment. The
wobble could well be because I chose to fill these with sand instead of
salt, for at least two reasons:
- Taken to an extreme, if I replaced all the sand with one big rock that
weighed the same as the sand, the ball would wobble like crazy. And at the
other extreme, as has been discussed, if the sand was replaced with a
liquid at the same weight, they'd almost surely wobble less (until the
point they started spilling liquid all over my carpet ;-) So intuitively
the less "lumpy" or coarse the filling is, the more smoothly the weight is
going to redistribute, and the less wobble
- It also seems very likely the volume of the fill is going to matter. If
you filled the balls with something that weighed the same as the sand but
filled the entire ball, very likely you'd see no wobble at all (but you'd
also lose that often-discussed "catchability" of a russian ball). It is
quite possible that I've altered the percentage of the volume fill of the
ball a lot. Not only are the 3" balls substantially larger in volume than
a 2.5", and the increase in weight may not have made up for the increase
in volume, but if the sand is more dense than the salt, it may not be
filling up as much volume per the same unit of weight.
Maybe I'll make a test set of 3" balls at the same weight but filled with
salt. And then I'll make a set filled with milk, and test those out over
somebody elses carpet. Any volunteers?
Little Paul
> I know when I played with yours, I saw lots of wobble, so I'm convinced at
> least part of the difference is that you're a hell of a juggler :-) But
> you do raise a good point. I was quick to assume the difference was due to
> the size and weight, when it wasn't exactly a controlled experiment. The
> wobble could well be because I chose to fill these with sand instead of
> salt, for at least two reasons:
When you filled them with sand, did you bake the sand first? Or just use
the sand how you found it?
If there is any moisture in the sand, the grains of sand will stick together.
If they stick together, then you get clumps forming. These clumps stop the
sand from distributing itself evenly during the throw and you get wobble.
> - Taken to an extreme, if I replaced all the sand with one big rock that
> weighed the same as the sand, the ball would wobble like crazy. And at the
> other extreme, as has been discussed, if the sand was replaced with a
> liquid at the same weight, they'd almost surely wobble less (until the
> point they started spilling liquid all over my carpet ;-)
That would depend on the viscosity of the liquid. The more viscous the
liquid is, the more it clings to the side of the ball and the more wobble
you get (just like with the wet sand)
Play did a lot of research and development until they found a filling for
their sil-x balls which had a suitable viscosity but was food safe. Water
(or milk for that matter) isn't suitable.
-Paul
--
http://paulseward.com
dpawson
>
> When you filled them with sand, did you bake the sand first? Or just use
> the sand how you found it?
>
> If there is any moisture in the sand, the grains of sand will stick together.
> If they stick together, then you get clumps forming. These clumps stop the
> sand from distributing itself evenly during the throw and you get wobble.
>
Point well taken, because at that point you effectively get the "big rock
in the ball" that I mentioned. While I didn't bake my sand, I don't have
any reason to believe my sand is clumping, and I'd be pretty surprised.
Just a big ole 50 pound bag of sand purchased from Home Depot. If the sand
on my floor and shirt are any indication, it is dry as a bone.
Boppo
I don't agree. Wobble comes from spin, not from clumps. (What is a
ball, except one big clump?) The way I throw balls is a bit like jai-
alai, they kind of roll off my hands. As you accelerate the ball
upwards for the throw, all the filling collects in the bottom. Then,
centrifugal force (if the ball is spinning) keeps it there, or most of
it there, and this imbalances the ball. So to the extent that it
spins, it wobbles.
Somebody recently commented upon seeing me juggle beanbags how much I
spin them. I used to use Russians years ago, and they wobbled like
crazy, but it's not because the filling was moist. It wasn't. Some
people throw balls without any spin. If they used Russians, they
wouldn't wobble - even if there were nothing but clumps inside.
-boppo
dpawson
> I don't agree. Wobble comes from spin, not from clumps. (What is a
> ball, except one big clump?) The way I throw balls is a bit like jai-
> alai, they kind of roll off my hands. As you accelerate the ball
> upwards for the throw, all the filling collects in the bottom. Then,
> centrifugal force (if the ball is spinning) keeps it there, or most of
> it there, and this imbalances the ball. So to the extent that it
> spins, it wobbles.
>
> Somebody recently commented upon seeing me juggle beanbags how much I
> spin them. I used to use Russians years ago, and they wobbled like
> crazy, but it's not because the filling was moist. It wasn't. Some
> people throw balls without any spin. If they used Russians, they
> wouldn't wobble - even if there were nothing but clumps inside.
>
> -boppo
>
a "russian ball" with nothing inside, it isn't going to wobble no matter
how much you spin it; I suppose it might curve like a baseball curveball
depending on the surface, but I don't see why/how it would wobble.
Similarly, if you throw a "russian ball" with a jawbreaker inside, but you
don't spin it at all, it also isn't going to wobble. But if you spin the
ball, and it has something inside of it that is willing to shift the
weight unevenly, it wobbles.
No?
Juggling fool
and softballs (to try out different ball sizes) to make spin more
noticeable, and juggled on camera for a little. As I juggle more objects
or make higher throws the balls have more and more spin. However, when I
juggle with russians, even for higher numbers and faster throw speed, I
have noticed no wobble with the russians I use (thegoheads brand), and i
have not changed my throwing technique. For some very demostrative video,
see http://www.youtube.com/watch?v=x6RGECw3E9g where he obviously throws
with extremely fast spin as the pattern progresses, and he now uses
russians (either thegoheads brand or brontosaurus, i'm not sure, we're
both 3-inchers though), and has noticed no wobble of any sort. See
http://www.youtube.com/watch?v=_kmEaVl6qo4
It's possible that there is some sort of spin cap that one must hit before
a russian begins to wobble, which could be determined through more
jugglers with different spin doing this, preferably with same sized
objects, only changing from beanbag or stage ball to russian, and with the
"test" being redone for many different brands of russian.
Boppo
My argument was against moisture being the main difference between one
person's Russians, which wobbled, and another's which didn't. Being
careful to avoid moisture in the filling might indeed be wise to avoid
mold or spoilage, but has little or nothing to do with wobble. Even a
dry filling will cling intermally to one side of the ball, if it's
thrown and spun as I described, and even a badly internally-clumped,
moist Russian will NOT wobble if thrown without spin.
In other words, wobble is a spin/no spin issue, not a moist/dry
issue. Although I will agree the filling should be dry for the other,
good reason of avoiding spoilage.
-boppo, reporting on centrifugal force without the usual spin
dpawson
>
> My argument was against moisture being the main difference between one
> person's Russians, which wobbled, and another's which didn't. Being
> careful to avoid moisture in the filling might indeed be wise to avoid
> mold or spoilage, but has little or nothing to do with wobble. Even a
> dry filling will cling intermally to one side of the ball, if it's
> thrown and spun as I described, and even a badly internally-clumped,
> moist Russian will NOT wobble if thrown without spin.
>
> In other words, wobble is a spin/no spin issue, not a moist/dry
> issue. Although I will agree the filling should be dry for the other,
> good reason of avoiding spoilage.
>
> -boppo, reporting on centrifugal force without the usual spin
>
>
whether a russian would wobble more if it had 80 grams of kitty litter in
it, or 80 moistened grams of kitty litter in it that had clumped into one
big sphere. With identical spin, you wouldn't expect those two examples to
wobble the same, would you? (Unless the identical spin was no spin at all
heh)
(Bonus question: you (Boppo) and I have 1 relatively close degree of
separation from each other. What is the connection? :-)
Boppo
With no spin, they would wobble the same (none). With a lot of spin,
they would wobble the same (a lot - centrifugal force "clumps" even
dry kitty litter all to one side of the ball, making it wobble even
worse than the clump would - because it's pressed all the way against
the wall). With intermediate spin, they will both wobble a little. I
will concede there are symmetric (wobble-free-if-spinning) mass
distributions accessible to the dry litter ball that are inaccessible
to the wet litter ball, but in my opinion they span only a small space
of realistic throw heights and spins. That's my opinion, and it could
be wrong, but that's what I think. If juggler x uses Russians and
they wobble, and juggler y uses Russians and they don't wobble, I
think it's much more probable that x spins the balls and y doesn't,
than that y was careful to use dry filling but x wasn't.
As to your bonus question, I have no idea.
-boppo, knows what he knows and what he doesn't know, but doesn't know
who he knows knows
dpawson
> With no spin, they would wobble the same (none). With a lot of spin,
> they would wobble the same (a lot - centrifugal force "clumps" even
> dry kitty litter all to one side of the ball, making it wobble even
> worse than the clump would - because it's pressed all the way against
> the wall). With intermediate spin, they will both wobble a little. I
> will concede there are symmetric (wobble-free-if-spinning) mass
> distributions accessible to the dry litter ball that are inaccessible
> to the wet litter ball, but in my opinion they span only a small space
> of realistic throw heights and spins. That's my opinion, and it could
> be wrong, but that's what I think. If juggler x uses Russians and
> they wobble, and juggler y uses Russians and they don't wobble, I
> think it's much more probable that x spins the balls and y doesn't,
> than that y was careful to use dry filling but x wasn't.
>
but I also would agree that the problem with a wobbly throw is more likely
to be the way it was thrown than whether some of the sand inside happens
to have clumped.
> As to your bonus question, I have no idea.
I would have been surprised. At some point I figured out that I
tangentially know you, because I dated your sister-in-law for four years
(certainly before she married your brother :-) I've socialized with the
two of them on various occasions, and had heard about his brother who
juggled a lot, and eventually put the pieces together.
>
> -boppo, knows what he knows and what he doesn't know, but doesn't know
> who he knows knows
Now you know me. Kinda. Sorta. Not really.
Dave
TK
>>> My argument was against moisture being the main difference between one
>>> person's Russians, which wobbled, and another's which didn't. Being
>>> careful to avoid moisture in the filling might indeed be wise to avoid
>>> mold or spoilage, but has little or nothing to do with wobble. Even a
>>> dry filling will cling intermally to one side of the ball, if it's
>>> thrown and spun as I described, and even a badly internally-clumped,
>>> moist Russian will NOT wobble if thrown without spin.
My experience shows dry material centrifuging to the ends (axis of
rotation) causing no wobble while wet and/or sticky material can land on
the equator of the ball which will induce great wobble. The exception
being when the dry centrifuged sand hits the internal seam at an angle
all bets are off.
Boppo
> Unless you are the lead dog, the view never changes.
How can dry material "centrifuge" to the axis? Dry or wet, it will go
to the equator. Only little helium balloons would centrifuge to the
equator. (When you drive a helium balloon in a car, and slam on the
brakes, the balloon goes to the back of the car.)
I used Russians a long time ago, homemade street hockey balls filled
with sand, rice, or BBs at one time or another. They all had dry
fillings, and all wobbled significantly - because my throws spin the
balls. The BB-filled balls had a hard-hitting impact and were
objectionably noisy, so aren't recommended. The sand- and rice-filled
ones were nice, but I couldn't do numbers with them as well as with
beanbags, so I eventually lost interest in them.
-boppo
Johntsellick
I've been using homemade play pit balls filled to 85g with millet, and
I've never seen the slightest wobble. I might just be a strange person who
doesn't notice that kind of thing, as they are the only russian balls I
have ever used, but I've learned 7 balls with them without any problems.
Marlon
>
> I've been using homemade play pit balls filled to 85g with millet
How do you make play pit balls?
Little Paul
> Johntsellick wrote:
>>
>> I've been using homemade play pit balls filled to 85g with millet
>
> How do you make play pit balls?
See this: http://idsamp.wordpress.com/2010/07/28/diy-personal-blow-molding-gun
Of course, you'll need to put a bit of effort in to make a suitable mold.
-Paul
--
http://paulseward.com
..maks
> I've been using homemade play pit balls filled to 85g with millet, and
> I've never seen the slightest wobble. I might just be a strange person who
> doesn't notice that kind of thing, as they are the only russian balls I
> have ever used, but I've learned 7 balls with them without any problems.
>
Pretty much the same with me. I still reckon that is got to do with how
much you spin the balls if you are causing any wobble.
Maks,