Your patience has paid off--it’s time for the final print of the Millenbaugh Motivator! All the measurements have been made, a rough version has been completed, the final version has been modeled and prototypes printed. After three months of work, it was time to get this delivered to Adam. And that meant making a flight back out to San Francisco.
For my previous prints, such as the Octopod and Jetcar builds, I’ve used the trusty Objet Connex500. It's a high-end polyjet printer that can print in various materials--even rubber. But as much as I like this machine, I also had access to a 3D Systems ProJet 7000 HD which could print at even higher resolutions and in stronger material, all of which would be especially useful for the Motivator. The ProJet is a SLA (stereolithography) machine that prints by ‘drawing’ the part in a vat of liquid resin using a laser that solidifies the UV sensitive material. Once a layer is finished, the print platform sinks further down in the resin, a fresh layer of resin is distributed over the top and the laser draws the next layer. The resolution can be set incredibly high, and I was told the parts would be dimensionally accurate, meaning a hole modeled at 3mm in diameter would print at exactly 3mm.
I was a bit skeptical of this claim, since typically you need to factor in some tolerances when modeling to accommodate the accuracy of the printer and behavior of the material. This has caused me frustration when 3D printing since a model built with tolerances for one printer won’t always print well on a different printer. I have done various versions of the same model with slight tweaks for different printers--an annoying and time-consuming task.