Saturday April 19, 2014

Sensable Phantom and Freeform: Sculpting for engineers

In the June issue of Design World, I wrote about Organic Shape Modeling for Engineers. In that article, I said that Geomagic’s Sensable Phantom haptic devices, when used in conjunction with their Freeform and Freeform Plus modeling software, are arguably the “gold standard for organic shape modeling.”

A couple of weeks ago, I was in North Carolina, at Geomagic’s headquarters, and got to spend some more time working with the Phantom and Freeform Plus. I stand by my statement: It’s what I’d want if I were modeling organic shapes for manufacturing.

PhantomDesktop Large 271x300The Phantom/Freeform Plus combination is a “secret weapon” that transforms workflows for products with organic shapes. It does this by supporting voxel (essentially, 3 dimensional pixel) based modeling, with haptics (force feedback.) Using a Phantom with Freeform is like modeling clay with a stylus. (Sensable calls it “digital clay.”) You can actually “feel” the surface you’re pushing against with the Phantom.

Consider a well-known toy company that makes a brand of popular dolls that children have been playing with throughout the last 50 years. I won’t tell you their name, because I’ve not asked their permission to do so. This company employs designers—artists, really—who used to hand sculpt all their new designs for dolls and accessories. And, believe me, this doll has a lot of accessories. The time to sculpt and prototype dolls and accessories was a major impediment in getting products to market quickly. The company went to a digital process, using the Phantom, Freeform, and 3D printing (though in this case, it may be better to call it “rapid prototyping.”) It took time and patience for the company’s designers to get comfortable with the new technology. But they did. (Using a Tom Sawyer approach. The designers doing hand scultping saw how much fun the ones using digital scultping were having.) The improvement in their ability to get products to market quickly was amazing. No, we’re not talking about some small percentage improvement; we’re talking about a complete transformation, with critical processes going from months to days.

BaldwinCouture 300x300One company that uses Freeform Plus, and is willing to admit it publicly, is Baldwin Hardware. Look at this image of knobs, from the Baldwin Couture collection. They have the kind of fine detail that you can’t easily manage with a typical 3D NURBS-based CAD system. (Baldwin created these by importing the base knob geometry into Freeform Plus from Pro/E, and importing the texture as 2D designs from Adobe Photoshop.) Baldwin designer Yoss Singtoroj estimates that what takes him 1 day to do in Freeform Plus would take 20 days in Pro/E. And, if he wanted to make changes in Pro/E, he’d have to start over.

While this example from Baldwin shows some of what Freeform can do, there are many applications that are close to home for engineers who are designing products that aren’t particularly organicly shaped, in and of themselves.

Snowmobile tank mTo the left is an example of using Freeform Plus to model a gas tank for a snowmobile. The first image shows a shape, imported in Parasolid format and converted to digital clay (voxels), that defines the volume available for the gas tank. Its shape is derived from surfaces of all the parts surrounding the area, and it’s definitely not pretty.

The second image shows the volume smoothed, blended, and with proper drafts to allow molding.Unlike in CAD systems, blending operations in Freeform Plus literally never fail. Drafts can be adjusted manually or automatically, based on mold pull direction, and where you want the parting line.

The third image shows surfaces overlaid on the digital clay model. The next image shows those surfaces stitched together into a solid, ready for export to the CAD system. (These surfaces can now be created manually or automatically.)

The last image shows a comparison between the original volume, and the final model of the gas tank.

A little detail that isn’t shown: Such a complicated shape can be very difficult for CAD systems to shell. No matter: Freeform Plus can accurately shell the digital clay model, no matter how nasty its shape. And, unlike CAD systems, its offset function never fails.

The rest of the process for this tank would involve sending the model (as a NURBS solid) back to CAD, for the addition of precision mounting interfaces, the filler neck, and the outlet. And, finally, the model could be sent back to Freeform Plus to create the parting line, and mold cores and cavities.

In the best of all worlds, CAD systems would be good enough to handle problems like this one. But this is not the best of all worlds. While it’s possible that a really good CAD system could handle the surface offsets, blends, smoothing, drafting, and shelling for the original part, I’d personally shudder when it came time to change some of the surrounding parts, and rebuild the gas tank based on those changes. This is a difficult problem, made easy by digital clay modeling in Freeform Plus.

After Geomagic’s acquisition of Sensable earlier this year, I was curious about what made the deal particularly attractive for Geomagic. While I was visiting the company, I had a chance to talk to Geomagic founder Ping Fu, and ask her about this. She pointed to Freeform as a significant factor. It’s a very strong voxel-based modeler, with the ability to work in a design/manufacturing workflow, and it’s a natural companion to Geomagic Studio.

Geomagic/Sensable actually offers three flavors of modeling tools, all based on the same core: Freeform, Freeform Plus, and Claytools.

Claytools contains a subset of Freeform’s capabilities, ideal for modeling organic shapes in sculpture and jewelry. It works with applications that support stl and obj file formats (including, particularly, Rhino), and can output data for rapid prototyping or casting.

Freeform adds quite a bit of capability tuned to the needs of modeling organic shapes for manufacturing. It’s Freeform Plus, however, that’s the hot ticket. It includes support for NURBS solids and surfaces, and a nice set of tools to prep parts for manufacturing, and to design mold cores and cavities:

  • Design/Prep for Manufacturability
    • Set Pull Direction, Undercut Display
    • Fix Draft, Fix Draft Selection
    • Parting Line Tools – Definition, Evaluation and Editing
    • Shelling
    • Split Joint Design
    • Reference Import Solid Geometry from CAD
  • Mold Design
    • Split Mesh
    • Offset Curve Segments
    • Mold Insert Definition
    • Planar Parting Line Sections
    • Parting Surface Creation – Extruded, Shape Clay and Patches, Complex Transitional Parting Surface
    • 3D to Planar Parting Surface Definition
    • Trim Parting Surface
    • Multiple Component Creation
    • Preview/Create Core & Cavity Inserts

Sensable has just released new versions of Freeform and Claytools, with some significant new capabilities. All the new versions (Freeform, Freeform Plus, and Claytools) get improvements in modeling, including:

  • Curve Spheres – replicating the sculptor’s real world armature, allows designers and sculptors to quickly create volumetric models controlled by an underlying curve skeleton. Allowing quick volume studies, fast re-posing and base model generation.
  • New Mesh tools, such as Mesh Division, allow a toy designer, for example, to take an animated character model that is highly faceted, and in 1 or 2 clicks replace the facets with a smooth surface ready for production.
  • Paint – ability to paint models and project or map imported images onto models
  • Enhanced Carving tools, a new Pipe tool, improved capabilities for modeling with curves
  • Hot Wax Tool – replicating more subtle techniques, this allows sculptors to gain a finer control when sculpting, as well as combining multiple tools into one for a faster, more natural workflow.

3dconnex hero 300x176Freeform and Freeform Plus gain support for 3D Connexion’s SpacePilot Pro and SpaceMouse Pro, for enhanced two-handed 3D manipulation. (If you get one of these, you’ll wonder how you did without it.)

Finally, Freeform Plus gets advanced auto-surfacing capabilities, incorporated from Geomagic Studio. This lets users automatically convert Freeform voxel or polygonal models into solid and surface models, so they can be imported into CAD programs such as SolidWorks or Creo. These imported models can be built upon in the CAD program, to create free-form parts with precision mating surfaces and interfaces. Auto-surfaced parts can also be imported into CAM products for tool path generation. (But here’s a little secret: some of the best CAM programs are capable of directly using polygonal models.)

The advanced auto-surfacing capability is a dividend from Geomagic’s acquisition of Sensable. It’s nice to see cases like this, where a corporate acquisition actually ends up benefiting users.


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