RepRap 3D Printer - Prusa i3 - Build Log: Part 0

There has been much said about 3D printers and the coming manufacturing revolution in the media and online. You can now buy plenty of sub $1000 Fused Deposition Modelling (FDM, also known as Fused Filament Fabrication, FFF) 3D printers. The technology behind FDM 3D printing was brought to the masses by the RepRap project, which aims to publish open source plans for a self replicating 3D printer. After many months of reading and hearing about this new technology, I decided to jump in and try to build myself a 3D printer.

The Prusa i3 3D printer

Having never built a 3D printer before, I certainly underestimated the time and headaches that would be involved. But the result is rewarding and has expanded my knowledge. I have tried to document my thoughts and processes, so that others can give this project a go, hopefully with less headbashing.

Which One?

There are LOTS of different 3D printers available. LOTS. But all the different varieties can be divided into a few broad categories: Open Source or Closed Source; Community project or private project; prebuilt, kit, or DIY. Being a maker and tinkerer I wanted to be as hands on as possible and the easy choice for me was the RepRap project - a community run, open source project which is available in kits or in self sourced DIY.

Within the RepRap project there are currently six different versions of printer:

  1. Original Mendel
  2. MendelMax
  3. Prusa Mendel
  4. Wallace
  5. RepRapPro Huxley
  6. RepRapPro Tricolour Mendel
The Original Mendel is the most senior of the designs and is the basis for the MendelMax, Prusa Mendel and RepRapPro Tricolour. The most recent design (and the design currently undergoing the most development as of July 2013) is the Prusa Mendel. However the Prusa Mendel itself comes in three iterations with the most current being the Prusa i3 and the Prusa i3 is available in three variations - Aluminium single plate frame, gusseted wood frame and box wood frame. Even the Prusa i3 has several variants such as the EiNSTeiN variant and the Rework variant. 

So which one? Well after a lot of reading I decided on the standard Prusa i3 Aluminium frame option. I believe the aluminium frame is much more professional looking and sturdy than the wood options, and the i3 is the most advanced design with the best technology. However, the i3 is a work-in-progress and the design is still evolving, making some parts of the build (such as finding proper documentation) difficult. The EiNSTeiN variant is also very popular and I was seriously considering this variant, but the standard i3 won out.


Options, options, options. Almost every part of the i3 (or any RapRap) has multiple different variants and options to choose from. This has it's advantages, as it acts as a kind of evolution pathway for the project. With every different option there will be better designs and worse designs and the better ones will become more popular and win out.

The extruder is the component which grips the plastic filament and forces it out of the hot end. The standard Prusa i3 (as hosted on GitHub) includes a very common extruder, Greg's Wade extruder (which itself is an evolution of Wade's Geared extruder). For ease of construction I used Greg's. There are other extruders which are very popular with the Prusa i3 such as the Compact Dual extruder (some people have noted problems with this extruder on the RepRap IRC) and the Metal Gear Solid extruder.

Hot End
The Hot End basically melts the plastic and has a nozzle through which the molten plastic squirts out. Again there are many variations of hot end - J-HeadBudaschnozzleExcaliburWildseyed. I was somewhat lost as to which hot end performed better, and feedback from the Reprap IRC led me to choose the J-Head. The J-head itself is available in 0.5mm, 0.4mm and 0.35mm nozzle diameters and suit 1.75mm or 3mm filament. I went with 3mm filament as it is more widely available than 1.75mm where I live. Although the smaller nozzles give more resolution to the print, my research indicated that smaller nozzles are more prone to clogs and problems and they increase the print time considerably, and as this is my first printer build, I went with the 0.5mm nozzle.

Once again there is a plethora of electronics available to control the printer. I wanted an electronics package that was widespread (so that support was easy to find) and flexible (so I could add and modify at a later stage). I went with RAMPS 1.4. This is a shield (daughter board) for the Arduino Mega. The Arduino does all the computation on its microprocessor and the RAMPS board provides the electronics for the stepper motor controllers and heaters etc. The advantage of having electronics which sit on an Arduino board, is that after the RAMPS is no longer of use, the Arduino is reusable in another project. Also, if something were to fail, only the failed component needs replacement, rather than the whole electronics unit.

Bill of Materials

I found it surprisingly difficult to find a full BOM for the Prusa i3 online, so here is my own version along with where I sourced the component and how much it cost. The costs DON'T INCLUDE SHIPPING AND/OR DUTIES. Some of the import duties I paid (here in Canada) were obscene. If I did this again I would try to source more components locally. I will endeavour to update the BOM as I go along if I find any more parts I need. Direct Link to SpreadSheet.

Build Instructions

As with the Bill of Materials, finding a complete set of Build Instructions was relatively difficult. There are many sets of instructions for various kits, and variations of the Prusa i3, but I am yet to find a set of instructions for the Prusa i3. I ended up using pieces of information from lots of sources (including members at my local HackSpace). Here are a few of the various build instructions I utilised.