Saturday, October 4, 2014

Operating 3D Printers As Small Factories

Frog and Fly – Ollie
The job flow running through a 3D printer or set of printers should be managed using processes like those used in small-scale factories or other job shops that handle small runs of custom piece work. The requirements for this job handling process includes a readily accessible and easy to understand form customers fill in to unambiguously describe the details of the job being submitted. The process must also provide the printer operators with an interface that enables them to process the job flow efficiently, optimize the quality of the objects being produced, keep costs down and track invoicing and payment for completed work.

In my presentations to teachers and administrators, I've demonstrated a spreadsheet that I've evolved for tracking 3D print jobs. I've also demonstrated a web form that my students are using to submit their jobs for printing and the complete set of Google Sheets -based backend tools used to process this work flow. I've used this new package of workflow tools to support a camp that I ran this past summer, in my 3D modeling classes, and in professional development seminars that I run at schools across the Bay Area. When taken together, the tools have so far been used for print production amounting to about 50kg of filament. In the last few months have I been able package up this set of production tools for others to use in their environments.

The web form that my customers, a.k.a. students, use to submit print jobs is based on a wonderful product called JotForm. After you create a free JotForm account you can create a copy of this form using the template I've made public here. As jarring as the form might feel the first time you see it in all it's yellow glory, this unique and unforgettable look helps students, some as young as 3rd graders, remember the job submission process so that I only have to explain it to them once. The "Show Instructions" checkbox near the top of the form is available for those that need their memories refreshed. As simple as the form is, it's complete enough to support single and dual extrusion jobs using any raw material and any configuration of outer shells and infill ratio.

An important feature of JotForm is what they call "integrations". These are processes that can be invoked when a form is submitted. I use the Google Sheets integration. This causes a fresh row to be added to a Google Sheets workbook for every job submitted. The Google Sheets integration wizard that is used to make this connection is very straightforward. But JotForm's behind-the-scenes code that adds these rows to the spreadsheet works by overwriting the workbook every time. This means that this workbook can’t be modified with custom calculations or additional sheets. Instead, IMPORTRANGE function of Google Sheets is used to synchronize these rows of job data into a range of cells in a separate tracker workbook.

I don’t need to fill out a web form when I set up a print job for myself. So this JotForm-based workflow is used only in an educational setting. The tracker workbook that I developed for tracking production of student jobs can be found here. The first sheet, named Submissions, uses Google’s IMPORTRANGE function in Columns F and beyond to import the data taken from the JotForm-generated workbook. Columns A to E of the Submissions sheet are used by the printer operator to denote the state of each job as to flows through the production process. (Note that the workbook referred to by the first argument of IMPORTRANGE must be changed to refer to the Google workbook that YOUR JotForm populates.)

Notice that column E is titled ‘Paid”. This workbook supports the use of 3DBucks. Teachers use 3DBucks to optimize printer demand and motivate students to maximize their progress through each lap of the innovation cycle. 3DBucks are credits that students must spend in order to print something. The cost of each print job is based on the amount of filament it consumes. Available 3DBucks denominations are 1 gram, 5 grams, 10 grams, 25 grams, and the special Dual credit. Students may be given Stipends, which are some 3DBucks given at the start of the semester, when a project is assigned or at some other point that makes sense in your classroom. Some classes use themed competitions and award the students who succeed the furthest beyond their range. I reserve dual passes for “amazing” designs that are best rendered in two-color print jobs. The Balances, Stipends, Awards and Prints sheets of the tracker workbook are used to track the flow of credits in a 3DBucks -based economy.

My tracker workbook can be used as-is, or as a starting point for other tracking work flows better suited for small to mid-sized industrial, retail or creative environments. Have at it.