Laser Cut Prototyping Made Easy
marcteer@blackspectacles.com

Marc Teer

February 22, 2016

Laser Cut Prototyping Made Easy

A free tutorial on creating geometry for laser cut prototyping for Pepakura, from the Black Spectacles course on Architectural Prototyping with Rhino 5 and Grasshopper.

In this Black Spectacles FREE tutorial, you will learn about creating geometry for Pepakura. Pepekura is a free software platform that is fairly easy to use. It allows you to create three dimensional cut outs that can be used to make physical models of your design. This tutorial is part of the Black Spectacles course on Architectural Prototyping with Rhino 5 and Grasshopper.

View the entire course here: 
Architectural Prototyping with Rhino 5 and Grasshopper

Creating Geometry for Pepakura Tutorial

Step 1: Draw a box

Start a new model in Rhino. You are going to take a piece of geometry and make a polysurface out of it. We are going to begin with a box which you can draw manually by selecting “Solid” in the toolbar, then select “Box,” then choose “Corner to Corner, Height.” Then simply draw your box. Start at “0,0” for the “First corner of base.”

Step 3: Subtract a cylinder from the box

Next you are going to subtract a cylinder out of the center of the box. Before you can subtract it, you have to draw the cylinder first. To do this, go to “Solid” and select “Cylinder.” Find the center point of the cube, and draw a cylinder, pulling it upwards. 

Once you have your cylinder drawn and in the center of your box, you are going to subtract it from the cube. To do this you will use the BooleanDifference command which trims the shared areas of selected polysurfaces or surfaces with another set of polysurfaces or surfaces. To do this, go into “Solid Tools” and select the “BooleanDifference” command. Then select the cube, which is the surface you want to subtract from, and press “Enter.” Then select the cylinder, which is the surface to you want to subtract with, and press “Enter.”

If you then change your viewport style to shaded by going to the “Standard” tab and selecting the icon for “Shaded viewport display mode,” you will get a nice view of your cube which now has a hollow core. 

Step 4: Twist the cube

Next, you are going to actually twist the entire cube. Select the Command “Twist.” Then you must select where you want the start of the axis. In this case, it will be in the center of the cylinder at the bottom. Hold the Control key, click that center point again, and pull it upward through the cylinder to draw a vertical axis. And then twist the entire cube 180 degrees. Then, scale your cube up a bit so it looks more like a twisting tower with an interior core.  

Step 5: CageEdit the object

Now you are going to utilize the “CageEdit” command to sculpt this tower a little further. This command deforms objects smoothly using 2D and 3D cage objects. To do this, select “CageEdit” in the command field. And select “B” (BoundingBox) as the control object, “W” (World) as the coordinate system, “5” as the X point count, “5” as the Y point count, and “5” as the Z point count. Then press “Enter” to apply your selections.

From here you can play with the shape of the tower a bit more. You can take the top section of the tower and pull it up. Then take the flat surface on the very top of the tower and scale it down so you have an undulating, tapered tower. You can also make the middle section bulge out a bit. So you now have an elegant looking tower.

Step 6: Fillet the edges

Now that you have this geometry, there’s a few more things you can do with it. The first is to fillet the edges. Select the “FilletEdge” command. Then select one of the corner edges of your tower and adjust the radius slightly to fillet that edge a bit. 

Step 7: Add a handle

One of the options within the FilletEdge command is “AddHandle.” Handle curves are curves you draw by hand. You pick the curve point first, then pick your handle locations, and press Enter when you’re done. So you can take one corner edge of the tower and add a handle, starting it starts at the bottom of the tower as a minimal rounded corner, then have it flare out in the middle of the tower, and then taper back down to a smaller corner up top.

You can continue to play with that geometry and end up with something like this image. You can see the tower now has these wavy, rounded corners with the exception of one edge.

Step 8: Render the object

Next, select the “SetObjectDisplayMode” command, choose “M” (Mode) for the attributes for selected objects, and then choose “R” (rendered mode). This will give you a nice view of what your tower looks like smoothed out. You can see it has one hard edge, and some wavy, softer ones.

View the video for this tutorial here: 

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