After this step printer will be looking almost like finished.

Printed parts needed:

1x Z-axis-top-left
1x Z-axis-top-right
1x Z-axis-bottom-left
1x Z-axis-bottom-right

Follow the instructions, skipping step 4 (Placing Z-covers) and there is also additional steps needed with step 5, as we are using trapezoidal screws with aluminium couplers.

After placing the motors, install couplers and then insert trapezoidal screws into them, and tighten it all with the 4 screws on every coupler. Make sure that motor shaft and screw are not touching inside the couplers. Then go to Step 7, but as nuts use adapters and the chinese nuts.

After step 11 it should look like this:


I’m currently not managing the cables, as it will  be also managed differently than in Original, so Step 13 can be skipped. All the following steps can be easily followed from the Prusa manual.

I’ve changed my mind about the frame, and instead of using 6mm MDF i am using 9mm plywood, which is more stable, and still in good price comparing to aluminum. Because of that some screws which I am using are longer than in standard one.

Z-Axis before instaling GT2-belt

In next step we will make the printer moving, by installing RAMPS and connecting the motors which are already installed on frame.

Z-Axis Summary

Printed plastic parts

  • 1x Z-axis-top-left
  • 1x Z-axis-top-right
  • 1x Z-axis-bottom-left
  • 1x Z-axis-bottom-right

Metal parts

  • 2x linear shaft Φ8 320mm
  • 2x 5×8 aluminium coupler
  • 2x trapezoidal screw Tr8x8 with nut
  • 14x M3x18 screw
  • 8x M3x10 screw
  • 14x M3 nut


  • 2x NEMA17 stepper motor


  • 1x GT2 belt
  • 1x Prusa i3 vanilla frame (9mm plywood)

Y-Axis summary

Finalizing the Y-Axis

Finally, the GT2 belt and the pulleys came, so I was able to finish Y-Axis build.

From the two types of switches which i described on cost estimations, only the bigger ones are working properly. The switches from razer mouse are too small to MK2 parts. The metal parts can be removed from the switches, it will work then button-like, but its not necessary. I’ve done it with removing.

Fully assembled Y-Axis

Fully assembled Y-Axis

I am not soldering the cables right now, even to the endstop which need soldering very close to plastic parts.
I had also to reprint the motor holder, as i broke the previous part while screwing endstop, and its new green PLA 🙂 It will be printer made from many different colors.


The next step according to official manuals is build of the X-Axis.

Y-Axis Parts summary

Printed plastic parts

  • 4x Y-corner
  • 1x Y-belt-holder
  • 1x Y-motor-holder
  • 1x Y-idler
  • (optional) 1x Y-motor-distance

Metal parts

  • 2x Threaded rod M10x380
  • 1x Threaded rod M8x310
  • 3x Threaded rod M8x210
  • 2x Linear shaft Φ8 350mm (Original = 330mm, if you want to use shorter, take also M10 rods 20mm shorter – 360mm)
  • 3x ball bearing LM8UU
  • 12x M10 nut
  • 12x M10 washer
  • 16x M8 nut
  • 16x M8 washer
  • 3x M3 self-locking nut
  • 2x M3 washer
  • 1x M3x25 screw
  • 2x M3x12 screw
  • 2x M3x10 screw
  • 2x M2x12 screw
  • 1x GT2 idley pulley
  • 1x GT2-16 pulley


  • 1x NEMA17 stepper motor
  • 1x Microswitch


  • 3x zipties
  • 1x GT2 belt
  • (optional) 4x felt pad
  • (optional) 4x zipties

Y-axis part 1 and overall thoughts

The Y-axis

I have already some of the parts, so I decided to start the build.

Printed parts (from original) needed for this step:

4x Y-corner
1x Y-belt-holder
1x Y-motor-holder
1x Y-idler
1x Y-motor-distance (optional - MK2S element)

For this moment I’ve skipped the PSU-Y-part, as I will be thinking later about the power supply mounting.

The parts can be printed even from PLA, as the temperatures around that elements will be not so high.

Instructions can be taken directly from Prusa Manuals

Y-Axis Part 1

Preassembled Y-Axis

Joshep Prusa in the new revision of Original – MK2S – added addtonal clamps for the LM8UU bearings, removing the zipties. I think thats good idea, I’ve found some printed parts for securing the bearings – but mostly it will also raise the bed, and make the belt uneven.

LM8UU bearings holders

Bearings secured with element found on Thingiverse (made only for test)



I’ve wrote that there is need for direct hotend, but its wrong. As the original E3D always have connector for PTFE tube, and there is no difference between bowden and direct one, the Chinese ones for direct dont have  enough room to place the PTFE. I am not sure if this project will work without the PTFE tube between hotend and extruder, as the hole in extruder body are bigger than filament diameter it can lock over instead of pushing. With direct one also the tube can be glued to the hole in body, but I am not convinced if it will work. As I’ve already ordered the direct one, I will test both of the Chinese E3D clones.


The heatbed already came, I am testing it with the inductive sensor, and it looks promising. There is only one bad thing: the plastic are not sticking directly to the aluminium, and the heatbed has (unfortunately) some scratches and hole in center sealed with kapton tape.

There is two solutions which I see: glass with clips (I hate the clips) or dedicated printing surface like BuildTak or COROPad. Or both.

I’ve tested so far 3mm and 4mm glass with COROPad, and only on 3mm sensor was able to detect aluminium heatbed.

Probably I will finally stick the printing surface directly to the aluminium.

Trapezoidal screws

Trapezoidal screws are OK (but I also wonder if I shall use screw with 2mm lead instead 8mm), but the nuts are smaller than the ones in Original Prusa. There will be a need of adapter for that. I’ve seen already adapter on thingiverse, when I will be building that part I will try.

Inductive sensor

As the sensor will be working directly on 12V (because on 5V probably it will not work properly, but I will also verify that) its easier to use NPN instead of PNP. In cost estimation I wrote about NJK-5001A which is PNP, but fortunately it has also NPN equivalent named NJK-5001C (link to aliexpress).

The NPN are using GND signal when triggered, PNP are using high. If we will connect PNP sensor directly to 12V and the signal wire to arduino then it can burn the arduino port, unless we will make additional voltage divider eg. from two resistors.

I saw that Thomas Sanlanderer are almost finishing the build, but his approach is to build the printer as cheap as its possible. I am really surprised that he even chose M5 rods instead of trapezoidal ones, which IMHO are making the printer closer to MK1 instead of MK2. My approach are a little bit different – I want to build still a cheap printer, but with reasonable quality, and close to Original MK2.

The next part will be soon, as the only missing part to finish Y-axis is endstop.

Cost estimations

Its better to buy as many as possible parts at the begining, to avoid waiting for chinese ones in future. I’m always looking first at the local stores, to support local business, but if the price difference are very high – I am ordering on Aliexpress. I think its a good idea, to try support local store than Chinese one.


There is a plenty of options, in different price ranges. Mostly used materials are MDF, plywood, steel, aluminium and plexiglass.
The steel or aluminium are the best choice, and the worst option is plexiglass. From the cheap printers there is a plenty of printers made from plexi frame, but I think that MDF is better material for that purpose.
As the original Prusa i3 MK2 has 6mm thick frame, I will use same material thickness.

The aluminium universal frame cost at least 65 USD. Its too expensive for cheap project.
I haven’t found frame from steel which will fit that project. Going for P3Steel is also a good option – but it will result in a different printer, not the most faithful clone.

I will go for the MDF frame. Its very common, and cheap. At my place it cost less than 10 USD – its almost 7 times cheaper than the aluminium one!

Aluminium frame (Local vendor)
MDF frame (Local vendor)

Aluminium frame on Aliexpress (as example)
MDF Frame on Ebay (from Ukraine)

trapezoidal_screw_8mmTrapezoidal screws

For the build we need a trapezoidal screw for Z axis. Before 3D printers industry there was no real trapezoidal screws with 8mm diameter. Currently it can be bought from China (or local re-sellers). Original Prusa i3 MK2 has trapezoidal screws together with the stepper motors, but we will go cheaper – using flexible coupling.

In China there is also stepper motors with the trapezoidal screws available, but its very expensive. For one motor you have to spend around 33 USD (so 66 USD for two). It will came already with nut.

Trapezoidal screw with nut cost 3.96 USD per piece, and the flexible coupling is 0.86 USD per one. Together less than 10 USD.
For the remaining 56 USD I can buy all of the five required stepper motors. And a beer. And vodka. And a full tank of gas.

Stepper motor with trapezoidal screw and nut on Aliexpress

Trapezoidal screw with nut on Aliexpress
Flexible coupling 5×8 on Aliexpress

threaded_rodsThreaded rods

As on almost every Prusa i3, there is also Y-Axis build on a threaded rods. For the build we need a three M8x210mm, two M10x380mm and one M8x310mm. There is a difference between Original Prusa i3 MK2, and this build – the longer M8 threaded rod will be used to stabilize all the construction with the side supports from the frame, like it is at the Prusa i3 Rework. The lengths of rods are also not same as in Original Prusa i3 MK2, but should not make any difference.

I wanted to buy a black rods, with property class at least 8.8, and also I wanted also a cut ones. I’ve sent some requests to local vendors about cost with cut. Eventually I found only galvanized ones in good price, and I decided to take it.

The prices was really great: (per piece)
M10x380 – 0,58 USD
M8x310 – 0,32 USD
M8x210– 0,27 USD

Overall cost for the threaded rods: 2,02 USD (+ shipping by UPS or DHL 3,68 USD)

M8 threaded rods, galvanized, property class 8.8 (Local vendor)
M10 threaded rod, galvanized, property class 8.8 (Local vendor)

I strongly recommend to ask your local vendors for the threaded rods. Any store with metal parts should have it. Remember that You will also need a lot of screws, nuts and washers, so You will eventually go over there.
There is also a page available HERE about threaded rods itself, and also about a vendors.

66085e33768a8799af3775af47d3e214Linear shafts

The official manual of assembling Original Prusa i3 MK2 don’t have full information about smooth rods lengths. Because of that I took same sizes as in Rework.

  • 2x320mm Φ8 – Z Axis
  • 2x350mm Φ8 – Y Axis
  • 2x370mm Φ8 – X Axis (I didn’t checked yet if it will fit)

Section length 1000mm costs 6.14 USD at my local store, and the cut is for free.
Overall needed length = 2080mm, so it’s around 12,77 USD.
The shafts have hardness 62  HRC (+/- 1), and diameter tolerance h6.

I found also similar shafts on Aliexpress, and also with offer for cut. I didn’t asked the seller for details, but – 350mm cost 4.75 USD, so for the 2080mm it should be around 28,22 USD. Maybe after contacting the seller directly it will be cheaper, but the shafts are heavy so shipping cannot be cheap.
I strongly recommend to check on your local metal parts store, probably you will get it in good price.

Linear shaft 1000mm Φ8 (Local store)

Linear shaft 2x350mm Φ8 on Aliexpress


For the hotend the Chinese version of E3D V6 Full-metal will be used. Even if we have to buy a few of them from China to make one fully working, it will be still cheaper than buying original one. It has to be a cheap clone 🙂

There is nothing special about the Chinese hotends, lets choose with nozzle 0.4, without bowden connector (direct one) and without fan.

The cheapest one which I found its for 3.04 USD. Its always better to buy more than one – they are often not perfectly working, sometimes its required to take some parts from different hotends, and make one from them.

E3D V6 Full Metal Direct with heater and thermistor on Alliexpress


The Original Prusa i3 MK2 has a new heatbed called MK42. It’s impossible to get that heatbed without all the Original Prusa, only the Prusa Research are selling it. The Chinese people still didnt made a clone of that. Because of that we will use the older heatbed – the aluminium MK3. Its necessary to get aluminium plate, because we will be also using the self-leveling. We will be also setting this clone to print directly on the aluminium heatbed.

It should be cheaper to buy the heatbed, thermistor and the cables separately, but I’ve bought “all-in-one” package – it cost 13.81 USD.

Lot of Chinese are also making MK3 heatbeds calling it MK2A. Sometimes its cheaper to buy a aluminium heatbed with MK2A name on it, than with MK3 – and its same product.

Heatbed MK3 214x214x3mm on Aliexpress

nema17-1-8deg-40mm-stepper-motorStepper motors

There is a plenty of the motors, but we are focusing on the price. About the motors there can be done a lot of guides, but its not a case when we want to build a reliable and cheap printer.

The cheapest NEMA17 which i found on Aliexpress are sets of 5x 17HS4401 motors with free shipping for 41.00 USD.

Occasionally it is possible to find cheaper motors – you need to carefully watch for the ebay and other portals, to get the best offer.

For more information about the motors, I recommend THIS LINK.

5x 17HS4401 stepper motor on Aliexpress

0j3807-1200Main electronics

The Original Prusa i3 MK2 are using RAMBo electronics. Its not cheap (80 USD on Aliexpress). I will use the one of the most known electronics – Arduino MEGA 2560 + RAMPS 1.4 and 4x stepper drivers A4988. Additionaly we will take also the RepRapDiscount Smart Controller 2004LCD.

Full set – to make it as one click on Aliexpress will cost us 22.45 USD. I’ve took that.

If we will be looking for it separately (and with the cheapest prices):

  • Arduino MEGA 2560 – 7,85 USD
  • RAMPS 1.4 – 3,69 USD
  • 4x Stepper driver A4988 – 2,92 USD
  • RepRapDiscount Smart Controller 2004LCD -7.49 USD

Buying separately: 21.95 USD (0,50 USD cheaper)

Set of Arduino MEGA 2560 + RAMPS + Stepper drivers + LCD on Aliexpress

Arduino MEGA 2560
Stepper driver A4988
RepRapDiscount Smart Controller 2004LCD

power_supplyPower supply

We need to buy a power supply, with at least 240W of power (20A at 12V). Smaller can also work, but the 240W one are still not too expensive, and will have some additional power over the 200W power supply.

Cost: 16.83 USD

Power supply 240W/12V on Aliexpress

Other parts


To make the auto-leveling working, we need a inductive sensor. Because our heatbed is made from aluminium, not from the steel, and it’s only 3mm thick, its better to get a sensor which will detect metal from more than 4mm. It will for sure not detect our aluminium headbed from that distance, but the most important is that it will detect our bed at all.
And we need to remember, that the sensor has to be with M8 thread. Price: 1.69 USD + shipping (I didn’t found a sensor with free shipping)

NJK 5001A inductive sensor on Aliexpress

The auto-leveling are working like Z-axis endstop, but we still need a endstops for X and Y axis. There are boards available on Aliexpress, but its better to buy just microswitches, as they don’t have “3D printer” inside the name on Aliexpress, so they are mostly cheaper than “endstops for 3d printer”.
10x microswitch = 1.45 USD

10x 3 pin microswitches on Aliexpress
10x 3pin microswitches more like the original ones, on Aliexpress

Other materials

250px_lozyskolmLM8UU bearings

To allow slight move of our parts we need also some moving parts. For sure we will need LM8UU bearings – 3x for Y Axis, 3x for X Carriage, and 4x for Z Axis. 10x LM8UU will cost us 5.49 USD.

10x LM8UU bearings on Aliexpress

pulleybeltgt2_kit_1024x1024GT2 Belts, pulleys, and “pulley idlers”

We will need also GT2 timing belt, 2x GT2-16 pulley for X and Y Axis.
5 meters of GT2 belt should be enough – 4.98 USD
The GT2 pulley with 16 teeth cost 0.90 USD
Overall: 6.78 USD

For the belts we have also to provide the tension rollers, or a bearings. The tension rollers are available on Aliexpress, but it just hidden under the “pulley idler” title.
Two “pulley idlers” without teeth = 2x 0.99 USD = 1.98 USD

Tension roller aka pulley idler on Aliexpress

5 meters of GT2 belt on Aliexpress
GT2-16 pulley on Aliexpress


filament_drive_gear_mk8To be able to print we need something which push the filament. Lets use the MK8 Drive gear from China. It’s a cheap part – 0.56 USD.

We need also a 625 bearing and a short shaft (or threaded rod) – 5×16.
For the 625 we can use ZZ or 2RS type. The 2RS have better protection, and as there can be a lot of filament scraps I recommend to buy it, but it’s a little bit more expensive. In the calculations I will take the 625ZZ price.
625ZZ – 1.60 USD / 10pcs
625 2RS – 0.30 USD + shipping = 1.80 USD / 1pcs
Short shaft – 5.75 USD / 10pcs

Overall extruder cost: 7.91 USD

Extruder Drive gear MK8 on Aliexpress

625ZZ bearing on Aliexpress
625 2RS bearing on Aliexpress

5×16 shafts on Aliexpress


The printer have two cooling fans – one for the heater block on hotend, and one to cool the printed plastic. For the printed plastic cooling fan 5015 at 12V is used. Cost: 0.53 USD.

For the heater block we need a 30×30 fan. Cost: 0.65 USD.

Overall cooling cost: 1.18 USD

5015 fan on Aliexpress
30x30x10 fan on Aliexpress

Screws, washers, nuts, springs

sruba-czarna-82105-klasa-8-8-10-100mmTo build a printer we need also screws, washers and nuts. Mostly the M2 and M3 are needed, but there is some places where other types are required (M8 and M10 for the Y-Axis). Its hard to calculate a cost for that right now, because I am even not sure what amount of what type of screws will be used. We will also need some springs (for the extruder and (not required) for the headbed).

When the build will be finished, and the printer will be working all the necessary information about additional materials will be in Bill of materials.

Lets assume that all the screws, washers and nuts will cost around 15 USD.


  1. MDF Frame – 10,00 USD
  2. Trapezoidal screws – 10,00 USD
  3. Threaded rods – 2,02 USD
  4. Linear guides – 12,77 USD
  5. Hotend E3D V6 Full-metal – 3,04 USD
  6. Heatbed MK3 – 13,81 USD
  7. 5x NEMA17 Stepper motor – 41,00 USD
  8. Main electronics – 22,45 USD
  9. Power supply – 16,83 USD
  10. Inductive sensor – 1,69 USD
  11. Endstops – 1,45 USD
  12. LM8UU bearings – 5,49 USD
  13. GT2 belt and pulleys – 6,78 USD
  14. Tension rollers aka “puller idlers” – 1,98 USD
  15. Extruder parts – 7,91 USD
  16. Cooling fans – 1,18 USD
  17. Screws, nuts, washers, springs – 15,00 USD

Total: 173,04 USD

I believe that I’ve included everything what is required to build the printer. If its not everything, then the assembly will take longer (by time needed to get new parts from China).

Stay tuned for the next part!