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Turntable: state at the end of the workshop

This is the last state of the Turning disk, at the end of the workshop.

Initially the intention was to explore soundwise a specific kind of circular movement: steel surfaces spinning one on the other, in the form of a kind of ball bearings, say with balls who allow the spinning, but without a central axis.

The way i wanted to document the movement was sound.

Originally i planned to grind tracks on a iron surface, but since the found disks were much thinner than expected, i went further welding instead of grinding.

Interesting point: the best tracks had to be drawn without interruption, but the protection mask doesn’t allow to see the lines to follow, but welding without mask wouldn’t have allowed me to see at all, afterwards. I solved the problem marking the line with a white marker. The white sign still wasn’t visible, but while i was welding, the material of the marks would burn some millimeter before the noodle would arrive, making clear the direction where to continue.

The central axis had to be introduced, the tracks couldn’t be made big enough to keep the construction so firmly.

The welding made a lot of little spheres on the surface, which produced more sound, but were jamming the spheres much more. They had to be grinded away.

The first motor is placed on the top, fixed on an arm that goes outside. The movement is possible, but it jams pretty easily and just a little side pressure on the arm is able to let it move again. I added a second motor to hit constantly the arm on the side: in case of stop, with some pushes the disks starts spinning again, extending a lot the life span of the action.

Here the video of the presentation.

For the presentation I used 6 piezos to mix up the different sounds together and to be able to control them and look for the interesting resonant frequencies.

During the whole workshop I have been recording the sound produced, here a the whole documentation in chronological order.

Next steps: the next development stage would be making the rotation more stable, finding a way to keep the spheres separate, which could be done physically adding some blocks, like small walls, or adding a third disk with holes that would act exactly as the internal structure of a bearings. This would probably generate a lot of friction, that would in a way mean more sound, if the movement starts.

Otherwise another possibility would be making the tracks much higher, in order to keep always the balls in position, and adding enough balls not to give the possibility of having one side without them, that would mean no distance between the disks and therefore no movement.

Here some pictures, to show the result in its own beauty.

Surprisingly, it really looks like a sort of reversed turntable or proto – hard drive, which I like somehow very much, since apparently fits with the sound produced.


Spinning Wheel_DAY3

Here the results of the last day of workshop!

#1 Central axis – welding.

#2 Track corrections with welding and then grinding.

Discovered: the metal deforms very much. Before the corrections, but after yesterday’s welding, the plates were both concave, then they became convex, changing radically the distance between them and the behavior of the marbles.
The correction of the tracks + the central axis let them spin very safely, it happens now rarely, that they jump off the track.

Still the tracks are pretty much irregular, the higher one is a little too thin, so the friction is pretty high and the marbles hit on the sides producing strong noises.
#3 Add the two motors.

The main one is letting the upper disk spin, but sometimes has not enough power/friction to bring it forward. The second motor has an irregular cam that let the main motor oscillate, making the whole movement more uncertain and irregular.

#4 Wooden basis +  tuning.
All the pieces should fit together, somehow. I fixed them on one of the famous DOKA Holzplatte!



Piezo under the first disk.

Piezo under the metal basis.

Piezo under the wooden basis.


The sound changes radically at every layer of the structure.

High is more resonant, the middle highlights the hits and the first motor, the lower the second motor.
Nice that the frequencies are a bit enhanced, much more interesting the irregular pauses, where is possible to listen the friction of the gum against the iron.

In the presentation i will try with different piezos controllable in different channels.

AESTHETICALLY i have been surprised, what it actually turned out to be is something like a weird mixture and subversion of a turntable, but visually reminds of a huge version of a HDD. Conceptually they are even fitting very well together.


#to do next.

The next future steps would be….
– A bit better tracks. //maybe a chain could be welded on the spinning wheel, a stable result will be for sure easier to reach. -> interesting maybe for the several different little steps.
– More natural start and stop (controlled with an algorithm). More breaks.
– Keep the spheres separate/at the same distance (avoid jamming).
– Adding a second wheel? More complex rhythm…


Done today:
– BASIS ready
– TRACKS completely soldered (to be corrected).
– cooking.



Recordings of the day:

The first one has been done applying the piezo under the basis, more low frequencies.

The second one had the piezo directly sticked to the lower plate. Generally the volume is higher and the higher frequencies are dominant. The resonance of the plate is more evident, sounds a bit like a gong or a tibetan bell.

CONTRA: less low freqs.

To try out_ going even slower, to enhance the frequencies and have less violent hits.

TWO piezos?

– central axis.
– apply the motor. Superslow.
– corrections of the tracks / cleanup.

Try maybe with more piezos, placed in different places.

Spinning_wheel DAY ONE

Since the sound is the outcome of the wheel, i will focus on it.
I produced the sound spinning manually and very slowly the upper disk.

The sound of the wobbling glass marbles against the welded tracks is impressive, i really hope i didn’t mess up with the files. The recording has been done with a single piezo microphone.

//Done today:
– two tracks almost welded on one disk. (until i finished the welding iron…upsi!)
– tryout of the tracks
– recordings

// next steps:

– finish the welding on layer ONE.
– make it thicker on layer ONE.
– TRACKS on layer TWO

– basis (lover disk vibrates more)
– central axis (actually it is against the core, but the machine asks for it)

– motor driving the spinning

– more piezos (look for the more interesting sound)

– keep the balls separated?

1 2

Spinning Wheels construction Plan.

Found materials:

2 metal plates:
40cm diameter / 5 and 8 mm thickness

2 circular saw disks (Jure says “for cutting rocks! But in Slovenia we use them to keep the wife far from the shopping mall”)
ca 70cm diameter / 3-4 mm thickness

Washers of different dimensions / is it possible to weld them together?

Some wheels (a few. contemplated in the plan B)

half a bucket of glass Marbles


_ metal spheres _ for ball bearings


Construction Plan:

1 _Create a track on both of the external disks_

two possibilities: grinding or welding?
Two couples of disks: thicker would allow grinding, thinner would force to the welding of the contour.


2_ Keep the spheres separate _ as in ball bearings
Metal (smaller size)
Glass marbles (weight of the plate? 7/10kg _ maybe hole in the middle).


material needed ? wood or metal plates  around 2 mm
other_ washers together to weld in two circular figures.
the spheres should stay in between them. HIGH FRICTION very PROBABLE


2 B _ instead of metal/glass spheres _ use of wheels
CONTRA: just a few of them.
CONTRA 2: for loosers.


3_ apply motion _

possible ways:

NAILS on the side
or DIRECT CONTACT on the top. Image

located maybe on the bottom of the lower disk, or on other smart positions _ to be defined/discovered during the workshop.


The way of recording the movement is the audio one, finding an interesting balance between smooth movement and interesting sound.

The sound of the wheel.

I am interested in a very specific circular movement: the rotation of a disk on its own axis without a physical central axis, but rather on some kind of rails that allow this movement.

As a concrete example i take the structure of a Thrust ball bearings, the ones that are basically holding the weight of themselves and other objects on the top. The movement should then be driven by a motor touching the upper disk.

The idea would be, then, build the same kind of structure, in metal, but much bigger, let’s say with a diameter of 70 centimeters up to one meter.

Thrust-ball-bearing_din711_120-exI am currently working on the same kind of movement for my project for Ars Electronica; i built a wooden version of the same structure, in this case carving manually the wood. I discovered that the imprecision of the cut are making the whole structure vibrate and produce very interesting sounds.

For sure, the metal version of the object will have other very interesting sound features, which i would like to investigate.

Sadly, too many vibration make the disk jump outside the track, so my task will be find a satisfying  balance between sound and structural stability.