Simulating Water Drops on Wood
3 Steps
When I designed and built my own CNC, this is exactly the type of project I had in mind.  A chance to play with forms and test ideas, bringing things to life that would otherwise just live in my sketchbook.

In this Instructable I am going to show you how I simulated water drops in Photoshop for shape generation in Rhino 3D and eventual output to my DIY CNC.  This technique could also be applied to any 3 dimensional artwork that you can generate using light and dark to define object depth.

I am using water drops to show the advanced ability using layers to simulate the interaction of waves with each other resulting in a very believable final model.

The software used:

Photoshop
Rhino 3D
RhinoCAM
Mach3

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## Step 1: - 23 Setting up the Simulation in Photoshop

Step 1:  To begin you will need to find a source image of water drops so that you can study the relationship of the wave spacing and intensity.  You might find one that is better than the one I used.

Step 2: Bring that image into Photoshop and draw vertical lines at the peaks and valleys of the waves.

Step 3: Select the Gradient Tool.

Step 4: Click on the window in the options bar that shows the active gradient ramp. This opens the Gradient Editor Dialogue box.

Step 5: Click underneath the gradient bar to add more color swatches.  Add as many swatches as you have peak and valley lines.

Step 6:  Expand the window horizontally until the gradient bar spans these vertical lines representing the peaks and valleys.  Arrange the newly created swatches inline with your reference marks.

Step 7: We will now define the colors of these swatches keeping in mind the visual reference of the source water drop image.  We will be defining the depth of the waves based on white to black gradient, so we want to start with a base color of 50% on the CMYK scale.  Double click on the swatch to open the color picker dialogue box.

The values I used were the following from left to right.

10 | 60 | 10 | 70 | 20| 70 | 25 | 60 | 45 | 55 | 50

another way to look at this to get an idea of relative amplitude of the waves...

+40 | -20 | +40 | -30 | +30 | -20 | +25 | -10 | +5 | -5 | 0

If the rings are a long way from the center, the first value might be 50 (flat) and the swatches would slide farther to the right on the scale and remain relatively unchanged.

Step 8:  We will now set a transparency ramp for the new gradient.  Click above the gradient scale to create a new swatch and move it toward the end of the scale.  You should now have 3 swatches above the scale. Set the two on the left to black (opaque) the far right one to white (transparent) this will end the gradient when it reaches the edge of our ripples.

Step 9:  Click on New to add the newly created gradient to the list of Presets.

Step 10:  Now you will need to create a new Photoshop document.  Click File>New and in the New Document Dialogue box, input a width of 10000 pixels and a height of 5000 pixels.  And make sure that it is RGB color.  Rhino will not read a CMYK formatted document.

Step 11:  Insert a new layer in the layer control box.

Step 12:  Using the grid and guide lines, make a box in the middle of document select it with the rectangular marquee tool.  You could do this image full bleed, but I prefer to have a little elbow room when moving things around.

Step 13:  Set the color to 0% C 0% M 0% Y 50% K and bucket fill the rectangle.

Step 14:  Insert new Layer.

Step 16:  Click in the center of the document and drag away from the center, releasing near the edge of the field of grey.

Step 17:  Now you should have what looks like a target.  We now need to set the Opacity and Fill values to 50% so layers will mix when overlaid.

Step 18:  Select the move tool and while holding down ALT, drag another copy of the layer made in Step 16.  Note the interference produced.  Also note that where two light area cross, the image gets lighter and where two dark areas cross, the image gets darker.

Step 19:  Make more copies and scale and compose as much as you like.

Step 20:  When you are done, select the field (or part of it) and select Edit>Copy Merged.

Step 21:  Go to File>New.  The values should already be automatically set for what is on the clipboard. Make sure it is RGB mode and Click OK

Step 22:  Go to Image>Auto Contrast.  This takes the whitest area and makes it white and the darkest area and make it black.

Step 23:  Save this image.

Now that we have the final image, we are ready to bring it into Rhino and use the gradients to define 3 dimensional geometry for rendering or to make an actual object.

(If you wanted to do a 3D laser engraving of this image, you are already done as most laser cutters support raster engraving.)

remskm says: Sep 3, 2012. 10:22 AM
Want ot add another "beautifully done!" Thanks for your generosity in sharing your technique with us mere mortals. May I ask what version of Photoshop you used in this process? Thanks!
zoomenok says: Mar 26, 2012. 8:40 AM
Thanks for sharing. I've just started to learn cnc. Your instructable is very interesting. If it possible, can you describe step 31. I'm new with Rhino.
Thank you.
Grunblau (author) says: Mar 26, 2012. 1:25 PM
Sure! When I set up a CNC file I like to have as much real world information in the 3D model as I can. This step refers to modeling the actual material that you will be cutting. For the water drop file, I had a piece of wood (the stock)in my hand that was approximately 4"X12"X0.25". I modeled this in 3D and then I placed it at the origin. This is the center of the universe as far as your CAD program is concerned. The lower left hand corner of the the top face of this new stock model should be placed at 0,0,0 (origin). This can be done by selecting it and starting the move command, then snap to the lower left hand corner of the top of the stock and typing 0. (shortcut for 0,0,0)

When you Zero the CNC machine, this is sort of syncing the real world with the virtual world. Giving a point of reference for all of the coordinates in the gcode. So when you zero your CNC machine, be sure to zero it at the same place as you put the origin in your CAD geometry. If you place the geometry to be milled within this 3D stock volume, you know it will be cut into the stock.

Hope this helps!
zoomenok says: Mar 26, 2012. 8:45 PM
Thanks a lot Brian! It does!
DavAnt says: Mar 17, 2012. 7:06 AM
Hey, is there still somewhere we can get plans for your CNC in the vid? It looks really awesome!

Thanks
Grunblau (author) says: Mar 17, 2012. 2:48 PM

http://www.grunblau.com/CNCBMO.htm

And yes, the plans are still available!
bertus52x11 says: Mar 12, 2012. 4:45 AM
Awesome! I'm going to try this.
Oh and BTW, I just voted for you!
Confounded Machine says: Mar 10, 2012. 7:39 PM
Awesome!

After seeing your router build over on CNCzone I knew I needed to mill some water drop patterns on my machine (which drew upon design elements in your build). Nice to see you have documented the process.

Beautiful work as usual.

Grunblau (author) says: Mar 8, 2012. 4:22 PM
Thank you for the great comments!

I have done this on a larger scale, I milled an entire IKEA butcher block counter top.  It took over 16 hours to complete!

I sort of let a cat out of the bag on this one, but I hope to do well in the "Make it Real" competition!

-Brian
GameVortexGeck0 says: Mar 8, 2012. 2:05 PM
A suggestion to take this to the next level: Make a table or bar surface with this treatment, then cover it with clear epoxy. Then, you'd have the appearance of a clear, rippled top, but with a smooth finish.

Awesome project.
timothymh says: Mar 8, 2012. 2:05 PM
This is terrific! I've voted on it, for sure. :D
canemaker49 says: Mar 8, 2012. 1:57 PM
this effect would look very cool on boxes. very nice job!
Microbe says: Mar 8, 2012. 1:09 PM
It looks great, but wouldn't balancing something like a wine glass be difficult?

Also, WTF happened to the chips of wood being removed?
specialk22tt says: Mar 8, 2012. 10:25 AM
Way to take it to the next level. Strong work.
askjerry says: Mar 8, 2012. 6:57 AM
It's not enough that your project uses a really great idea...

You get the two thumbs up because you went the extra distance and provided a really detailed step-by-step instructable. This is what sets your project apart from many others.

Excellent job!
Jerry
Machine says: Mar 8, 2012. 5:56 AM
Very nice.

It's where creativity meets furniture meets electronics meets clever use of tools.

That is superb. You have my vote.
WWC says: Mar 5, 2012. 7:22 PM
Hi. That is so very good. I too have a DIY CNC i am working on. When i think about CNC project i usually think in terms of big 3D, bust or something with big shapes. But to see your project with only small shapes or low height for the 3D is very cool. It gives a hole new perspective on what can be made. Thanks.
fozzy13 says: Mar 5, 2012. 4:14 PM
This is so cool!! You have my vote for the Shopbot contest.
ChrysN says: Mar 5, 2012. 4:10 PM
That looks gorgeous!
imBobertRobert says: Mar 5, 2012. 2:02 PM
you should start selling these for.. say, \$25 for a small piece?
HandyLandy says: Mar 5, 2012. 12:28 PM
Love the idea! Can't wait to try this. I think it would be amazing on a large scale with a poured finish!
Jeff-of-all-trades says: Mar 5, 2012. 4:03 AM
Just plain awesome.