RepRap Prusa i3 build

From Random Projects
Jump to: navigation, search

This page documents my DIY build (as of 05/2015) of a RepRap Prusa i3 based Open Hardware (and Open Source) 3D printer.

I'm sourcing all parts "manually" (i.e. I'm neither buying a finished product nor a kit) and building the hardware from scratch.

Note: This is the first time that I'm building a 3D printer and as of 05/2015 it's still work in progress, so please don't consider anything written here as 100% accurate. Pretty much everything could change at any time.


Here are some of the main goals for this 3D printer:

  • It should be a completely Open Hardware and Open Source 3D printer.
    • I want to be able to modify any part of the firmware/software as I see fit.
      • All the required firmware and (cross-platform) software should have a proper open-source license.
    • I want to be able to also modify (almost) all parts of the hardware.
      • All printed parts (i.e., 3D models / STL files) should have a proper open-source/open-hardware license.
      • All printed parts should have the source files of the respective CAD program used available under a proper open-source/open-hardware license.
      • All printed parts should be designed in a (cross-platform) CAD program that has a proper open-source license.
  • It should be able to print pretty much any filament/material available on the market.
    • I want to try out all kinds of special-purpose filament, and I don't want to be limited to just printing PLA (as is the case with some other printers).
  • It should be as silent as reasonably possible.
    • I'll probably be operating the printer in my living room or the like, so it will be designed to be as silent as (reasonably) possible.
  • It should produce reasonably good-quality output.
    • I'm not looking for a device that gets some low-quality results, it should be a reasonably good-quality output (even if that means higher price).


Some things that are not my main goals:

  • It doesn't have to be ultra-cheap.
    • I don't aim to build the cheapest-possible 3D printer. If that's your goal, I recommend buying a finished device or a kit from eBay,, or some of the specialized 3D printer shops.
  • It doesn't have to be ultra-fast.
    • Printing reasonably fast is nice, but I'm not trying to optimize this build to be the fastest-possible 3D printer.

Design choices

Filament diameter



I decided to use the E3D-v6 hotend, 1.75mm, Universal (Direct), 12V. As of 05/2015 it seems to be pretty much the best hotend on the market. Additionally, it also has a few nice properties that I've been looking for anyway. For example, it's a full-metal hotend that can reach temperatures up to 300°C (or even up to 400°C with certain modifications) hence making it possible to print a wide variety of materials, some of which need pretty high temperatures (e.g. Polycabonate or some Nylons). Also, it has been specifically designed to make it easier to print flexible filaments such as NinjaFlex, FlexPLA, FlexPolyester, and others.

Choice of E3D-v6 variant:

  • I use the 1.75mm version (not the 3mm version), since I decided to use 1.75mm filament (see above).
  • I use the 12V version (not the 24V version), since all the other electronics will be powered by a 12V power supply already.
  • I use the "direct" (non-Bowden) version, since Bowden-based printers have a very hard time printing flexible filaments (if at all).

More info:


Since one of the main goals is to be able to print any material (including various flexible ones), a Bowden-based setup will probably not work very well.

Thus, I'll be using a simple direct-drive extruder design with an MK8(-like) drive-gear.

Heated bed

In order to print some of the materials properly you need a heated bed that can be heated up to relatively high temperatures (110°C or more).

I'll be using the MK3 aluminum heatbed for now, though there are some other promising options I might switch to later on.

Stepper motors

5x Wantai 42BYGHW811 NEMA17, 2.5A, 47N-cm high torque axes stepper motors.

Stepper motor drivers

One of the main sources of noise in a 3D printer are the stepper motor drivers, so I'm choosing the drivers that should result in the lowest-possible noise.

As of 05/2015 these are certainly the Watterott SilentStepStick stepper drivers which are based on the Trinamic TMC2100 IC.

Linear bearings

Another source for a lot of noise are the (metal) linear bearings that most printers use (LM8UU in most cases).

I'll be using the Igus DryLin R - RJ4JP 01-08 linear bearings which are a drop-in replacement made out of a special kind of plastic and are a lot more silent than the metal LM8UUs.

Power supply

I'll be using a (somewhat expensive, unfortunately) fully-passive ATX power supply without any fans. This means there is no noise whatsoever from the power supply.



Plastic parts set


There are basically two types of Prusa i3 frames:

I'll be using the Single Sheet type frame.

There are various choices for the frame material (wood, MDF, acryl, aluminum, steel, plastic, others). Since I wanted a somewhat stable frame (that would not wiggle or deform easily, would not have moisture issues, and would not have issues with higher temperatures), I chose an aluminum frame.

There are various sources for those as well, of course. I personally decided to use the ooznest Prusa i3 6mm aluminium frame since it looks pretty nice, and I was planning to get a set of rods from ooznest anyway, so I went for the ooznest Prusa i3 Frame & Rod Kit.

Smooth rods

You'll need a few smooth rods for the Prusa i3 (2x 320mm, 2x 350mm, 2x 370mm, 1x 20mm).

It's pretty important to get precision ground smooth rods, ideally using hardened steel (not just stainless steel):

  • It will improve print quality (bent/uneven rods can drastically reduce the quality, linear bearings may not fit properly).
  • There will be less wear on the rods (and/or the linear bearings) and they won't bend or deform.
  • There will be less noise from the linear bearings (bent/uneven rods can cause rattle and loud noise).

See also the Reprap wiki page on smooth rods for more info.

I decided to get the ooznest Prusa i3 Hardened Steel Smooth Rods Kit (as part of the ooznest Prusa i3 Frame & Rod Kit).

Specs as per vendor12:

Key Value
Material cf53 hardened steel
Rockwell hardness 60-64Hrc

Threaded rods

You'll need a few threaded rods for the Prusa i3 (2x M5 300mm, 4x M8 205mm, 2x M10 380mm).

The requirements for the threaded rods aren't as high as for the smooth rods, they should mostly just be as straight as possible.

See also the Reprap wiki page on threaded rods for more info (and sources where you can buy them).

I decided to get the ooznest Prusa i3 Threaded Rods Kit (as part of the ooznest Prusa i3 Frame & Rod Kit), which are manufactured from A2 stainless steel.

Print surface

Borosilicate glass


Bill of materials

This bill of materials reflects the parts that I personally use in my 3D printer and where I bought them.

Some of the parts are optional, and for many of them there are alternative sources, of course. Since I live in Germany, I tried to buy most of the parts from German (or at least European) shops in order to avoid customs hassle, huge shipping costs, and long shipping times. Depending on where you live you might want to choose other shops. You can browse the Reprap Prusa i3 buyer's guide for that.

Part Source Price Design Comments
URL Country Author License Software
Mechanical parts
1x ooznest Prusa i3 6mm aluminium frame UK £50.00 ooznest ? ? Laser cut from 6mm 6082 Aluminium, then shot blast and edges rubbed down, then finished with a matt black powder coat. DXF file: ooznest-alu-6mm.dxf. Alternatives: eBay, others.
1x ooznest Prusa i3 Threaded Rods Kit UK £20.00 ooznest 2x M5 300mm, 4x M8 205mm, 2x M10 380mm. Alternatives: RepRap wiki list, eBay, others.
1x ooznest Prusa i3 Hardened Steel Smooth Rods Kit UK £35.00 ooznest 2x 320mm, 2x 350mm, 2x 370mm, 1x 20mm. Alternatives: eBay: gapimankr, marchantdice, others.
1x Borosilicate glass, 213mm x 200mm x 3mm ES €12.00 Alternatives: eBay: Geeetech,, others.
1x BuildTak 3D print surface, 203mm x 203 mm (8" x 8") ES €9.00 Ideal Jacobs Alternatives: distributors list,,, eBay, others.
1x E3D-v6 groove mounting plate UK £3.50 E3D
1x Bulldog clips (4 pieces) UK £0.90
2x Aluminum coupling (5mm to 5mm) DE €10.00 (2x €5.00)
2x GT2 pulley (20 teeth) DE €10.00 (2x €5.00)
2 meters of GT2 belt (6mm width, 2mm pitch) DE €7.60 (2x €3.80)
11x Igus DryLin R - RJ4JP 01-08 linear bearings DE €26.90 (buy 10+1 pieces) Igus
1x Aluminum Heatbed MK3 eBay DE €23.95 Sintron ? ? Alternatives: eBay, others.
1x E3D-v6 hotend, 1.75mm, Universal (Direct), 12V UK £43.00 E3D ? ? Alternatives: Genuine E3D resellers, others.
5x Wantai 42BYGHW811 NEMA17, 2.5A, 47N-cm high torque axes stepper motors UK £46.50 (5x €9.30) Wantai 1x X-axis, 1x Y-axis, 2x Z-axis, 1x hotend. Alternatives: eBay, others.
1x Arduino Mega 2560 R3 roboter-bausatz.de2 DE €52.902 ? ? ? Alternatives:, eBay, others.
1x RAMPS 1.4 roboter-bausatz.de2 DE €52.902 Johnny Russel (Ultimachine) GPLv3 Eagle Alternatives: eBay, others.
1x LCD 12864 RepRap Full Graphic Smart Controller roboter-bausatz.de2 DE €52.902 ? ? ? Alternatives:, eBay, others.
4x Watterott SilentStepStick stepper motor controllers DE €41.96 (4x €10.49) Stephan Watterott CC-BY-SA 4.0 Eagle 1x X-axis, 1x Y-axis, 1x Z-axis (even though there are 2 motors on the Z axis), 1x hotend. Alternatives:, others.
1x Super Flower SF-430P14FG fanless ATX power supply DE €111.89 Super Flower
Printed parts
4x Capped Y-Corners for Prusa i3 - fully parametrized enif CC-BY-SA 3.0 OpenSCAD

1 I actually bought the ooznest Prusa i3 Frame & Rod Kit (£95.00).
2 I actually bought the Ramps 1.4 kit + 12864 LCD controller + DRV8825 set (€52.90). I'll probably do a quick initial test of the Pololu DRV8825 stepper motors that come with the kit, but I'll use the Watterott SilentStepStick stepper motor controllers in the final build since they allow for much more silent/noiseless printing.




The frame that I bought came with 2.5mm holes drilled into it (the correct drill size for tapping the aluminum for M3 bolts), but no threads where you could attach M3 bolts. If that's the case for your frame as well, you'll have to tap the aluminum (i.e., create threads in the holes) yourself.

You can watch some video tutorials on how to do that, e.g.:

Stepper motors

The shaft of each stepper motor should be flat (at least on one side) to allow for at least one of the grub screws that'll be used to fasten the pulleys to the motor shaft to have a proper grip.

If your stepper motors didn't ship with the shaft pre-flattened, you'll have to do that yourself.

You can check various online resources on how to properly do that, or watch some Youtube video tutorial, for example:


I won't be describing the process of how to assemble the E3D-v6 hotend here in detail, it's well-documented in the E3D wiki and there are also a few pretty good video tutorials online:

Y axis

What you'll need:

  • Rods:
    • 2x 350mm M8 smooth rods
    • 4x 205mm M8 threaded rods
    • 2x 380mm M10 threaded rods
  • Printed parts:
    • 4x Y axis corners
    • 4x Y axis corner caps
    • 1x Y idler
    • 1x Y motor holder
  • Nuts, bolts and washers:
    • 12x M10 nuts (6 on each M10 threaded rod)
    • 4x M10 fender washers (2 on each M10 threaded rod)
    • 8x M10 washers (4 on each M10 threaded rod)
    • 22x M8 nuts (10x front, 12x back)
    • 22x M8 washers (10x front, 12x back)
    • 8x M3 nuts (2 go into each of the 4 Y corners)
    • 8x M3x12mm bolts (2 are used to screw on the cap of each of the 4 Y corners)