E3D hotend fan replacement on Prusa i3 MK2

So my Prusa i3 MK2 is printing just fine and I get awesome results with PLA and nGen. But two things are missing to be an perfect printer which is living room compatible.

The y-axis in comparison to the x- and z-axis is really loud. A few days ago I read on the Prusa website about an upgrade kit which includes new rods and bearings to eliminate this issue. So I will keep this in mind until the lead time is acceptable.

Second thing is the fan from the E3D hotend. It is an 30×30 fan which runs in full turbine mode. After reading in the forum I stumbled about a post with other users which had the same problem. One critical point was getting the same airflow as the small fan, so the hotend doesn’t clog during print. I found an nice 40x40x10 Noctua fan which fits my needs. It runs on 12V, creating an airflow of 8.2m³/h with an acoustical noise of 17.9dB(A).

For the adapter my co-worker printed an nice adapter in orange ABS (http://www.thingiverse.com/thing:1827477).


fig. 1 – Removing the old fan
fig. 2 – Mounting the adapter

The old fan was unscrewed and removed. With three M3x18 screws I mounted the new fan adapter.

fig. 3 – Mounting the new fan

Now I attached the new fan to the adapter. Be careful with the length of your screws. If your screws are to long they will damage the other fan.

fig. 4 – Connecting the fan

With my new fan came a short cable with a three pin connector. I removed the spiral wrap on the cables until I could get the fan cable plus the connector cable in there. The old fan wires where cut. Then I soldered the connector cable on the old wires and isolated the two wires from another.

fig. 5 – Spiral wrap attached again

For the last step I reattached the spiral wrap on all the cables. Check that the cable doesn’t touch the heated bed.

Noise level

Now that the fan noise is vanished the printer is really quiet. Only on the bed leveling procedure the y-axis makes noises. But now that the printer is so quiet I located a rattling noise which seems to come from the extruder. It only occurs some times during print and I couldn’t locate it further. I reassembled all the screws on the extruder, because it sounds like a loose nut. But this doesn’t help. I fastened the screws which mount the new fan which seems to fix it. But some times it occurs again.

But aside from that the printer now is quiet enough during print.


Prusa i3 MK2

Last year I purchased the new kit version of the original Prusa i3 MK2. It finally arrived and it was worth the waiting. I ordered the third printer only because I want to try building an printer. Both printers I already own are already assembled ones. So I said to me the Prusa has an bigger build volume and an interesting bed leveling function, this are good reasons to buy one :)

Here are some technical specifications for the kit version I purchased:

  • Build volume 25 x 21 x 20 cm
  • 0,4mm nozzle
  • 1,75mm filament diameter
  • E3D V6 Full hotend
  • PEI print surface & heatbed
  • Automatic mesh bed leveling (9 points)
  • Integrated controlboard which prints from SD card


Here are some pictures during the build. The build was so relaxing that I totally forget to do more pictures. Initially there was an time lapse planned for the build, but there are already some on Youtube, so I didn’t make it.

For the build I didn’t use the printed version of the manual. I used the online version because of the high resolution pictures included. I only had two small issues during the build.

Number one was the motor mount and belt holder on the Y-axis had not big enough holes to slide on the threaded rods. I screwed the threaded rods into the parts what gave me a headache after the assembly, when I tried to correct the position of this parts. Here I totally had to drill the holes wider first so that the parts can slide on the threaded rods.

Number two was the extruder assembly. To get this part together without M3 nuts falling out on each side was a little bit tricky … to put it charitably :)

And here is the final printer on its current position:


I already printed some parts on the new printer and the overall quality of the prints is simply awesome. But see for yourself:

This is the 3DBenchy (thingyverse link) which I tested with silver PLA and a layer height of 200µm.

This is a dual-color print which was on the SD card already. Here the print stopped after the silver part was printed. Then you can load new filament into the printer and extrude as much as you need to get the old color out. After the new color extrudes correctly you can resume the print with one click on the controlboard. This is a nice feature which I want to test more in the future.

Here is a stepper motor holder which I designed in Autodesk Fusion 360. I scaled the part to 102% and the stepper motor slides in smoothly. Also the print quality is amazing.

This is the hairy lion (thingyverse link) in silver PLA. Click on the image for a higher resolution. It came out beautifully.


So, I love the new Prusa i3 mk2 and I will print many things which doesn’t fit on the printbed of my Lulzbot Mini. But the Lulzbot Mini will be used also. Both machines are nice for starting a print and coming back later for the finished part. I can now use my box full of 1,75mm PLA from my first printer with the Prusa and print my 3mm HIPS with the Lulzbot. So no longer unused filament lying in the basement.

Thanks to Josef Prusa and his team for this amazing printer.

ESP8266 Ai-Thinker ESP-12 library for Eagle

Started working on an little ESP8266 project again. This time with an ESP-12 module from Ai-Thinker. Therefor I created an new part in Eagle after the specifications from Ai-Thinker (Technical Specifications).

My purchased module has an slightly different silkscreen as shown in the document. On my module GPIO4 and GPIO5 are swapped and pin EN is labeled CH_PD. That should be checked before using the part.

Library: https://github.com/cronJ/EagleLibrary

ESP-12_on_footprint ESP-12_and_footprint ESP-12_silkscreen

Growing peppers in 2016

So in this year I choose to only grow one type of peppers. It’s a jalapeno pepper. More specific it’s called a early jalapeno. After bloom they should carry green fruits after 60 days and red fruits after 80 days.

In this year I only grow in dirt because I had no time for preparing my drip bucket. But I changed the location of the peppers to a place where they can get more than 6 hours of sunlight. I hope that helps to grow nice bushy plants and not so tall ones like in the last years.

Unfortunatly I have no pictures from growing the seedlings to the current size. But I toke some pictures today after moving the plants in their smart bags.

The plants are now three months old and they are producing the second blooms. The first blooms where cut to allow the plant putting all their energy into growing. Now I have to watch the weather forecast and if we get a cold night I have to take the smart bags into the garage temporarely.

Getting NodeMCU running on an ESP-01 module in 2016


I tried to install NodeMCU with the help of my article from january 2015, but had some problems to do so. So I write a new article with a new approach, which works today. I also try to provide all new informations in englisch, because my site statistics say most of my visitors came from EU.


For the connection we need a serial interface. I use an FTDI UM232R module for this. To define the numbers on the ESP-01 module I use this drawing I created:


  1. GND
  2. UTXD
  3. GPIO2
  4. CH_PD
  5. GPIO0
  6. RST/GPIO16
  7. URXD
  8. VCC

You need at least three signals from your serial interface to the ESP-01 module. The signals are ground, RxD and TxD. The 3.3V supply voltage comes from my programmable power supply. The updated connection list is shown above.

The jumper JP1 on my UM232R module is set between pin 1 and 2 which defines 3.3V for the IOs.

Preparations for flashing NodeMCU

First we need the NodeMCU firmware. In the previous article you could download a pre-build binary from the GIT repository. I didn’t found a pre-build firmware on the repository today, so we have to build our own. Luckily there is an easy online firmware builder: nodemcu-build.com.

You have to enter a real email address, because you get your firmware download links via mail. I choose the master branch for my build and leave the default modules checked for a quick test. Then you have to click the “Start your build” button on the bottom of the page and wait until you got mail. I got two versions in the mail. One is labeled as an integer version and one as a float. For this article I’m using the integer one.


To flash the actual firmware I used a tool called nodemcu-flasher. I downloaded the 64bit version.

At this point be sure:

  • you connected your ESP-01 module to your serial interface
  • your module is supplied with a voltage of 3.3V
  • GPIO0 is set to ground and was at ground on power-up
  • CH_PD is set to VCC to enable the module
  • your serial interface is recognized by your OS

Now you can start the nodemcu-flasher. By default it will flash an integrated NodeMCU firmware, which can be outdated. Go to the “Config”-tab to select the new firmware you just created in the step before.

Default settings
My own firmware

Go to the “Operation”-tab and press the “Flash (F)” button to start the flash operation. The AP MAC and STA MAC should display correct values. If not and the progress bar don’t move, turn your module off and on again to enable flash mode. In flash mode wait until the progress bar is completely filled.

Firmware is being flashed
Flashing completed

Check your firmware

After flashing we need to check if the firmware is working. Turn off your ESP-01 module and remove GPIO0 from ground then power it on again. Connect with an terminal software to the serial interface which connects to your module. The baud rate has to be 9600.

For testing purpose I connected an red LED and a 470Ohm resistor in series to ground on GPIO2. In your terminal software you set GPIO2 to an output. The GPIO2 has the IO pin defined to 4! Your terminal should show something like this:

Now I enter the following line to set the IO pin to an output:

To switch the LED on I enter:


to turn the LED off.

If you can control the LED with this commands, congratulations, your NodeMCU firmware works.