Water Droplet Kinetic Sculpture

by videohead118 Sep 19, 2017
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Just made one of these. The basic design is wonderful, but I think a few things are lacking. My Prusa MK3 has done the Matt's Hub extruder calibration, as well as XYZ cube & other calibration objects, and it is pretty good on tolerances. It passed the Maker's Muse tolerance gauge down to .2mm, so it's not sloppy. That said...

The rings did not fit into the holes In the "strip" versions. Even after I used a deburring tool to remove the slight elephant's foot of the first layer being a tad squished on the strips, I ended up having to ream out the holes AND sand every ring support significantly to get everything to move somewhere near smoothly.

The center post, with the droplet, prints just fine in a vertical alignment if you use a brim & slow print speeds. But it is nowhere close to fitting into its hole in the strips. Again, deburred, reamed, reprinted the center piece @ 90% on X & Y, and still had to sand quite a bit to get it to move. Once I got everything moving, I noticed that the center post is much taller than the rest of the ring supports. This leads to the "droplet" never dropping below the surrounding rings (which it does in the video). I ended up physically clipping 25mm (1 inch) off the center post to make the droplet move below the surrounding rings at its low point.

I'm not talented enough with CAD to loosen the clearances between the strips & the ring supports, but if I were to reprint this, I would digitally chop 25mm off the center post and slim it down to about 80% on the X/Y axes before printing.

Conversely, the spacer & handle were very loose fits on the shaft, and therefore a little tricky to glue in place. I would probably digitally shim them in a CAD program to make them closer to a press fit. I'd also thicken the portion of the handle you actually grip to crank the machine. It's too thin and looks like a prime candidate for breakage.

All of that said... I am just picking nits. It's sort of my thing. I do NOT regret printing this. Took a lot of post processing, but the resulting machine is beautiful and entertaining to watch. THANK YOU for designing this fun & attractive machine. Beyond my CAD abilities, and I greatly appreciate the work that must have gone into it.

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This is a good model, and everything printed pretty well. Some of my thoughts based on having printed it:

  • You really do need to print the cam-shaft in the vertical position. I tried printing it horizontally and the cams ended up with rough surfaces that didn't work well at all.
  • Read the directions before you print, in the sense that you only need one of either the top or top strip (same for middle & middle strip), but you don't need both.
  • The rings were my major problem with this model. Printing the rings with the "legs" in the vertical position makes them far too brittle to be used. They are just waiting for a chance to snap off. I don't really have the time to do it now, but this model could be improved by printing the rings out in two parts: the rings themselves, and then the legs separately with some keying for them to fit into the rings to be glued (or friction fit). That way the legs could be printed horizontally and be strong enough to be used.

Still a good print and fun to make.

Hi there. I printed all of the parts at 100% using ABS (because apparently I am crazy) and the ring posts do not slide within the plates' holes. I sanded all of the holes in the plates and they still do not slide nicely. Just wondering if anyone else has had this issue? What did you do to fix it? I don't want to have wasted 20h on printing as well as all that filament but at this point I am not sure what to do.

how well does it print on a MakerBot replicator +

How nice and pleasant to watch!

I am having a hard time getting the rings to fit in the top and bottom strips. They do fit, however not well enough to slide nicely. So when I turn the knob, all of the rings go to their topmost point and stay there throughout the rotation of the knob and shaft. Is there any reccommended way of maybe scaling the strips so they are slightly larger? Perhaps there is a method of finishing the parts (acetone bath because I made from ABS)?

I know its more of a printer tolerances thing, but how small would one be able to print this? I have an MPSM and its print bed is small :P


Apart from the smallest pieces like the handle, according to Cura it should be printable at down to about 50% scale. Potentially lower, I haven't tried anything but full scale, though.

Is the center droplet suppose to be the same length as the rings? I had to reduce the size of the whole thing to fit my printer, but when printing the center droplet it’s longer and won’t fit in the hole at all.

Yeah dude I had the same issue. So i cut off about4mm of the length then drilled the holes a bit bigger for it fit properly

I had to print it at 88% (vs 100% for the rest)
Also printed a new droplet of 10mm with a hole of 4.5mm, much better now.

It seems a few other people had the same problem. The model is probably scaled improperly. I'll upload the properly scaled model later today.

Made one on my Ultimaker 2 mk2, ;-)
Used Ultimaker white pla for the base + discs. Base breaked when i inserted the shaft. (UM pla is brittle) Repaired. 0.1 / 20%
For the shaft i used aluminium grey Makerfill pla, with polysupport as support material. 0.2 / 20%
Rings are made of Polymaker Polymax blue, 0.1, 20%
The handle has a lot of play on the shaft, trying to glue it.
This thing makes a lot of noise when turning. Probably because i used 0.1 on rings and discs. If i would reprint, i would try an uneven combination, 0.1 in the rings, and 0.15 on the discs
I am going to print a "cover" in Colorfabb woodfill, think it will add tot the coolness of this thing.

very cool, I think it would be cool to have a few more rings on the outside for the ripple to die down some more.
I think what would also be really nice looking is to have the bottom enclosed, yes it will be more plastic but it would hide the magic inside making people wonder how it works. ;-)

how much plastic and how long does this take to print

There is literally a zillion ways to print this with a million variables. For 15 infill at 75% and 1.75mm about 18hrs.

Not made it myself, but my slicer seems to think it'll use about 264g of filament at 20% infill (235g at 10%).

As for print time, I'd guess in total at the very least 20 hours (could print some pieces quickly but I'm guessing you'd want to slow things down for the rings).

Beautiful. Begs the question though: what else can you make using this same concept? I expect great things...

This gives me an idea of a machine to make.
Using a crank for the cycle, it would make one drop of water fall at some precise moment in the cycle, and after a delay that could be tuned in the cycle (with a knob), would move very fast a slot through which one can see the drop impact in water. Turn the crank fast and maybe we could see the water frozen in time ?

This has been done electronically with a light sensor and a strobe, so that the light flashes at the precise moment the droplet is in a particular space, so it appears frozen. But a mechanical one would be fantastic!

Would it not be easier to split the to print center cam shaft in two vertical pieces so it would not require any supports. It can be split into 4 pieces the 2x sides and center cam with triangle holes.Then a triangle connector to line everything up to glue it. If you provide the cad file of cam shaft I could model it.

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Would you be willing to upload the original cad files so that edits can more easily be made.

You probably should give Dean O'Callaghan a mention since that's his design & video you've included (https://www.youtube.com/watch?v=ZqzjAmPFND8).

He got the idea from Reuben Margolin (https://www.reubenmargolin.com) as seen here: https://www.youtube.com/watch?v=qWjDWhrhuho.

Dunno who Reuben got the idea from, probably some Renaissance-era dude.

Thanks. I knew I had seen this before.

just an fyi the HANDLE is tilted 7' and the SPACER is tilted -1.25' had to adjust to get them to lay flat on the bed.

Thanks. Fixed it.

Just curious why the shaft (I am assuming the center pole with the "droplet" on top is the shaft?) would need support? just print it vertically ??

Actually the shaft is the long tall part with the multiple odd shaped circles. The best way I found to print that piece is vertically with supports to allow the circles themselves to be smooth. The droplet you're talking about can be printed on it's side or vertically but with the small contact area at the bottom, i prefer to print that on it's side with support too so that it wouldn't fall over while printing.

I think I got it


all the wee parts are done printing the rings now couple days it will all be done. JUST barely fit on my ender 2.

ahhhh man I missed that part!! though I think I know how to print it without support now that I am looking at it (will get back to you if it works)

stiction is no problem. my ender 2 (my little monster) combined with print in z can print amazingly tall widgets with super itty bitty contact patches. not even a brim is needed :-) though I will use one on this since its a curved bottom not flat.

if you rejiggered that part so the cams where SHARPENED with a 45' angle (and shifted as needed to center them again) it should print fine without support. but that would be really fugly to get right and hard to print on less than well tuned well behaved machines.

the idea I have would work on any printer. if it works i will let you know :-)