Comparison of 3D Printers
While there are many advanced 3D printing technologies, it is the low-cost ones that are of primary interest to OSE. The end goal of 3D printing technology is low-end 3D printers able to fabricate more advanced designs semi-autonomously. Achieving this Digital Fabrication objective has fairly wide-reaching economic implications, particularly when printed objects are used to bootstrap other manufacturing processes. (see Lost-PLA Casting)
The low-cost (sometimes called 'consumer-grade') 3D printers have been developed not by the corporate additive manufacturing developers, but by researchers and DIY enthusiasts mimicking the methods of commercial processes. The RepRap and Fab@Home projects both started with the goal of creating open source, desktop-sized, additive manufacturing platforms. RepRap was designed to use Fused Filament Fabrication (Compare with FDM), extruding ABS and eventually PLA. These materials allowed the production of structurally useful parts, allowing partial self-replication of RepRap systems. This has lead to their proliferation and mutation toward better and more robust designs through user-driven 'natural selection' process (A principle which will hopefully be applied to OSE designs!) Compare the success and proliferation of RepRap-based systems with those of the Fab@Home, which were not suitable for self-replication without a laser cutter (or a lot of effort).
Ideally, the construction of a 3D printer must be made with some understanding of the types of parts to be made. What size will they be? Your printer will have a build volume which limits the size of the parts it can produce. Check your build volume for any given design. If you're not making giant parts with it, your printer will not need a large build volume. What material do you want to print with? PLA is a fine starting choice, making solid parts and exhibiting limited warp when printed onto room temperature painter's tape. PLA prints at ~200C, and so almost any extruder should be capable of using it. ABS requires a higher nozzle temperature and exhibits significant warp without a heated bed (a useful upgrade). Higher-temperature thermoplastics (i.e. polycarbonate) require temperatures that most hot tips are not designed to handle, and these are not suggested for beginners.
Consumer-grade 3D printers
A comparison of 3D printer prices (for kits and assembled units) can be found here: http://www.3ders.org/pricecompare/3dprinters/
Commercial-grade 3D printers (typically >$5k)
[https://docs.google.com/spreadsheet/ccc?key=0ApN4BXK1pgnKdFdXenFkbnZxR1pIUGljR09MOWlLbkE&hl=en_US edit spreadsheet] *
- ZCorp (selective binding powder bed, proprietary materials :( )
- Fused Filament Fabrication (FFF), aka Fused Deposition Modeling (FDM)
- Syringe based extrusion (both mechanical and pressure based)
- Open Source Metal Printing (Using MIG-welder)
- Solar Sintering
- SLA (Stereolithography)