Those of you reading this who are familiar with Shapeways will know that their production team has design guidelines.  Those guidelines vary by material, and are included on the material page.  Here is the material page for laser-sintered nylon, which I what I most commonly make models out of.

These guidelines are just that: guidelines.  They are not set-in-stone rules, such that any model that is nonconforming cannot be printed.  However, Shapeways does not like to approve nonconforming models for production.  I was very happy when they introduced the “print it anyway” option, which allows artists such as myself to experiment with models that have features that would normally be rejected.

“Print it anyway” has proved to be a boon for my sailing ships.  The edges of the above-deck gunports usually fall below the recommended 0.7mm thickness, and the sails may have thin spots.  I try to design the sails such that they have an even 0.7mm thickness, but discrepencies due to the conversion of the .ipt to .stl file, as well as the slicing software for the printer itself, are inevitable.  There are some small features, such as railings, that I deliberately design to be as thin as 0.5mm, which works at 1/1000 scale, as the railings are never more than 1.5mm high.

However, a model can be 100% compliant with the design guidelines and not be a good design, even if the production team accepts it and runs it through.  Why?  Models can break.  As one can imagine, the masts of model ships fall under the feature category of “wires.”  Shapeways’ design guidelines for laser-sintered nylon recommend a minimum diameter of 1.0mm for wires of any given length.  For other materials, they have several different diameters, according to length, but for nylon, 1.0mm is the only recommendation listed, as of this writing.  I have discovered that, for most sailing ships, this is not sufficient by a long shot.  Depending on how tall the mast is, I may have to make it as thick as 2.0mm (at the base – masts are always tapered) in order for it to be reliably printed.

The previous two paragraphs are the very reason that some of my models, specifically the smaller and more intricate ones, must be validated before I can offer them for sale.  “Print it anyway” is available only to the designer of a model.  My customers cannot select that option when ordering one of my models.  When I was helping Tom Butler of Green Feet Games make prototypes of his game tokens for the Pirate Republic, I sent him the files so that he could use the “print it anyway” option on his own Shapeways account to validate the designs.

Many of my customers have asked me to scale down my sailing ships.  I currently offer a few of my designs in 1/1250 scale and 1/2000 scale as well as the original 1/1000 scale for the exact same models.  As you can imagine, scaling down the model means that I must make the masts and sails even thicker in the original .ipt file.  Thankfully, Shapeways’ 3D tools allows me to modify .stl files, so I don’t have to go back to my original model.  Nonetheless, any model that I had to validate in 1/1000 scale must be validated in a smaller scale before a customer can order it.  This is what takes so bloody long.  It takes no time on my part to change the scale of a model, but several days to validate the model file afterward.  Unless I am scaling up a model, as I recently did with my SU-12-180 turret (1/100 scale to 1/30 scale, per a customer request), I cannot simply re-scale a model and immediately offer it for sale.

My intent for this post was to make clear some of the challenges I face designing products for my customers.  3D printing is capable of some great feats that traditional manufacturing can only dream of.  However, the industry is still young, and while advancing rapidly, its capabilities are not infinite.  Most of the time, I am the one who bursts people’s bubbles and tells them that what they are asking is impossible.  However, I have occasionally been guilty myself of asking the impossible.

5 thoughts on “A Few Points About Validation

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