Desktop 3D Printing – Makerbot, RepRap et al

One tech of the Fab Lab/Hackerspace is the 3D printer, where an object is created by adding successive layers of material. There are a wide range of materials used – from frosting and clay, to various plastics, ceramics and even metals. Professional 3D printers started back in late ’80s with 3D Systems Stereo Lithography, which uses a laser to harden layers of liquid plastic. Today there are multiple vendors selling machines (StratasysObjet, Z-Corp, Dimension), with various technologies (laser sintering powders, etc).  All of these start with a 3D computer model of the part, slice it up into layers and then draw the layers with or onto the medium.   Sometimes the medium is a homogenous layer on which the machine draws (eg laser sinter metal/plastic, laser plastic curing, etc.)   other times the machine extrudes the medium.  The part takes shape as successive layers are created.  Some tech allows for ‘support material’ that supports overhangs and small parts while higher layers are built. The support material is removed later using a solvent wash or mechanical means (cutting).

All those neat commercial machines cost a fair chunk of money.  The ‘low priced’ HP branded DesignJet sells for about $17,500 (in europe). High end machines run into the hundreds of thousands of dollars. Not what small shops can afford!! There are a variety of service companies (eg Shapeways, RAPID Tech HI) to which you can upload designs and they will send you completed parts.  There is at least one directory of such service companies Rapid Today to help locate one nearby. (RAPID Technologies is our closest in Honolulu.)

On the other hand, there is the whole world of DIY hackers.  The granddaddy of the DIY 3D Printer is the RepRap – self replicating rapid prototyper.  They are currently on their 2nd generation design (Mendel) and are completely free and open source.  All designs and software are downloadable from the web.  There are a variety of child projects such as Fab@Home and Makerbot CNC.   I own a Makerbot Cupcake CNC, known as Goldbot.  It was built during a 3 day ‘Make-In” at CrashSpace in December 2009.  It will be one of the first machines available at Maui Makers.  The advent of these DIY tinkerer boxes was recently reported by the LA Times in the May 29 “These ‘printers’ make 3-D stuff” by Nathan Olivarez-Giles.  The article opens with Jay Leno’s use of a commercial machine to create parts for his antique car collection, and then moves quickly on to Sean Bonner of CrashSpace and Bre Pretis from Makerbot.  It closes with a quote from yours truly!  It also includes photos from Nathan’s visit to CrashSpace.

GoldBot and friends, (Michael Robinson Chavez / Los Angeles Times / February 23, 2010)

At present I am not the best evangelist for DIY 3D Printers. The current batch are definitely a tinkerers machine.  They take a lot of care and fussing to get good consistent results.  Some people have lots of success and I know some who actually make commercial parts with their machines. Alas, I am not in that category.  Goldbot suffers from a common malady of Makerbots – poor plastic feed.  The Makerbot uses a plastic wire (ABS or PLA) that it pushes down into a heat chamber and out a nozzle (a Plastruder).  One of the common failure modes is for the drive wheel to fail to properly grip the wire and slip, stopping the feed.  There are several reasons this happens and the Makerbot designers are all over the problem.  The new MK5 Plastruder has a new drive wheel that can be used in a MK4 Plastruder.  This, along with the redesigned heater and barrel of the MK5 should greatly reduce errors.  I am looking forward to installing one on Goldbot later this year, after I complete the move to Maui.

Design of parts is also an issue for all 3d printing.  You need some type of 3D CAD program – and these can be very expensive.  There are low cost/free alternatives, such as Google SketchUp and Blender, but all of them carry a learning curve – sometimes its pretty steep, more of a learning cliff.  3D Scanners exist (including DIY ones!) that can scan an existing object to create a 3d model.  After creating the raw model, the objects must be converted to proper format for the 3D printer.  This includes cutting it in layers and designing the tool path (speeds, geometry, etc).   The Makerbot tool chain includes several alternatives that are free.  The primary tool is SkeinForge which is really more of a collection of tools that handle various steps in the process.  SkeinFox is a Mac OSX application that simplifies control of SkeinForge.  There are LOTS of parameters to consider – some of which make a big difference in printing success, others dont seem to have much effect at all.  It takes a fair bit of experience to know what to tweak.  Then again, I have been fairly successful using some of the pre-canned parameter sets.

3D Printing will be a feature of Maui Makers.  Goldbot will be available for tinkerers. I plan to get some more experience with it myself so I can help others learn about the process and create.  There will, in time, be a wiki page tree for using our 3D printer.  I’ll update this post with links then.