Prototyping Workflow using the Silhouette Portrait

Long the tool of choice of scrapbookers and wedding invite makers, the humble electronic tool is finding itself more and more a part of industrial design workflows. Known to many as a Cricut machine (Cricut being a company that manufacturers these tools, think Kleenex versus tissues or Windex versus window cleaner) these “CNC knives” are very useful for a variety of design functions. A competitor to Circuit, the company known as Silhouette currently manufactures three machines with the entry level being the Portrait.  For full details you can visit the product page.

So there are four major use cases I have for the Portrait including:

• Quick 3D models of objects before they are sent to the 3D printer.
• Creating stencils for airbrushing logos and text onto project enclosures.
• Cutting vinyl for adhesive logos.
• Replacing the knife with a marker to create PCBs ready for etching.

I have not yet attempted the third use case of creating PCBs so I will save that for a later entry. For now, let’s focus on the workflows for the other use cases.

 

3D Models

Believe it or not, yes, you can create 3D objects from a flat piece of paper.  Card stock or some other heavy type of paper is recommended. While you are limited to smaller objects, the time needed to cut and tape together an object is far faster than sending a design to a 3D printer then finding a flaw that requires you to rework and print again. Here is recommended workflow for your next DIY project:

1. Create the model in SketchUp or 123D Design. Export the design to an STL file.
2. Next you will need to purchase an app called Pepakura that is currently Windows-only. This software is magic. It takes the 3D STL file and “unfolds” into a design that can be cut out from a sheet of paper.  From here you will need to export to a DXF file.
3. Silhouette offers free software for use with its electronic cutting machines, but you will have to spring for the $25 upgrade to the “Designer Edition” in order to import DXF files.  The upgraded version will also allow you to import SVG files as well.  Import your DXF file into your library and then drag it onto the virtual cutting mat.
4. You may have to adjust layers that are meant to be cut and those that are just to be perforated.  Right click the drawing and click “Ungroup”. You will be left with three layers, one where the lines are colored red, another one colored blue. and the last one black. Using the cutting options menu you can set each layer to cut or perforate.
5. That’s it, send it to your Silhouette device and let it cut it out.
6. Also of note, while I use the Silhouette Portrait, if you spring for the Curio there is an app that directly connects Pepakura to the XXX, making this workflow moot!

2D Drawings for Stencils and Vinyl

1. I first do my drawing in either Pixelmator or AutoDesk Graphic. Inkscape is a great option too. Once done, I export to SVG.  Be sure your design is no wider than 8 inches.
2. Again, after springing for the Designer Edition you will be able to import SVG files.  ENsure in setting that the SVG importer maintains the dimensions of the drawing and does not try to scale to fit.  I failed to do this once and the resulting cut out was much larger than I anticipated.
3. Drag the imported drawing onto the virtual cutting board and viola, you’re ready to send it to your SIlhouette machine.
4. WARNING: Once big reason of getting this machine was that you cannot cut vinyl in my laser cutter. The laser cutter causes the vinyl to release chlorine gas which I am told is very, very bad.

 

Last bit of advice, remember that you will have to both physically and in the software settings set your knife length to a sufficient length to cut through whatever material you are using.  Also, while the Portrait machine is not as expensive as even a modest 3D printer, it can be a bit expensive as a mere experiment. Keep an eye out for rather frequent sales on the company’s website, with discounts as deep as 44% sometimes being offered.