If I were the designer of the new Prusa CoreXY printer

I would consider

  • to check filament movement and detect jams
  • to use TMC 2209 with sensorless homing
  • to use dual z-axis with G34
  • to use something like a mosquito or a dragon hotend (V6 are a pain if you wan’t to change nozzles and the cooling is inferior to other designs)
  • to use a change tool mount like https://www.thingiverse.com/thing:3369444
  • not putting the belts unprotected on the top (not like the design of the Tronxy X5SA Pro)
  • make it rock solid like the Prusa i3 mk3s I have
  • use all the coole features of the i3 mk3s (like magnetic powder coated PEI sheet or the direct drive extruder)
  • having the possibility to easily attach walls to make a heated chamber
  • offering differrent sizes: normal like the i3 mk3s, large (330x330x400), extra large (400x400x500)

and to use me and myelf as betatesters… 🙂

Update 5 on Jun 22, 2020: Build log Tronxy X5SA Pro

Powder coated spring steel sheet arrived: https://www.aliexpress.com/item/4000209870583.htm

It is so nice to use. Big prints can be removed just by bending the plate. Well done!

I don’t understand, that someone would build a printer without a removable flexible build plate (thanks Josef :)) today. There is at least one much hyped printer on kickstarter that doesn’t have one…. 🙂 (And influencers may be paid for hyping it?)

Yes, I know I have to improve cable management… 🙂

Update 4 on Jun 18, 2020: Build log Tronxy X5SA Pro

Mosquito clone integrated into my build:


Added 3D Touch sensor. To use it for Z-homing, I had to use the predefined Z-min endstop pins and couldn’t use the pins provided by the SKR 1.4 board for BL Touch. I think, there is a bug in the version of Marlin I use.

Added extra stepper driver for each Z-motor. For the Z-axis alignment I use the 3DTouch sensor with Marlin G34.

Added BMG extruder clone.

And blown a 10A fuse…. 🙂

Update 3 on May 20, 2020: Build log Tronxy X5SA Pro

The SKR 1.4 Turbo board and 4.5 TFT E3.0 display arrived and replaced the Tronxy controller and display. I mounted the controller on the right side of the printer, as I intend to close the build chamber.

With the tmc 2209 drivers I do not need the endstop switches anymore. The inductive probe can be used for probing and Z-endstop (I had to solder a zener diode). It is WIP and there is much left to do. Here is my first benchy with the new controller (1 mm nozzle):

Problems with ABL and Octoprint are now gone…. 🙂

If you interested in my marlin configuration, here is my fork: https://github.com/FotoFieber/Marlin

Update 2 on May 9, 2020: Build log Tronxy X5SA Pro

What a cool idea: a Quick Tool Change found on https://www.thingiverse.com/thing:3369444

I adapted it to the Tronxy X5SA Pro https://www.thingiverse.com/thing:4337090

Then I remixed my remix of the V6 hotend for this Quick Tool Change https://www.thingiverse.com/thing:4345021

Inspired by all the ideas I found on thingiverse, I tried to print petg….

The build surface peeled completely off the build plate at 85 degree celsius. 🙁

(I have some blobs in my print too. The 1 mm nozzle must be tuned in in Cura.)

I sanded the surface down and try now with glue stick:

And then the filament run out and the chitu controller didn’t signal it to octoprint….

It is high time, the orders from china arrive:

  • new build surface
  • skr 1.4 turbo controller

Update 1 on april 22, 2020: Build log Tronxy X5SA Pro

Printed some nice drawers for my screws and nuts. Z-leveling is a pain as the two z-axes always get out of sync. I found a fix for the Tronxy X5SA https://www.thingiverse.com/thing:4297432 and adapted it for my setup: https://www.thingiverse.com/thing:4305634

The problems with octoprint may be fixed with a new plugin: https://plugins.octoprint.org/plugins/fixcbdfirmware/

The build plate is worn out, the coating peels off. I now print with a cooler heat bed and wait until it is cold, before I take the prints off. Hopefully the z-axis fix does bring a further relief.

Build log of my Tronxy X5SA Pro up to april 17, 2020

This blog post reflects the fun I have with my Tronxy X5SA Pro as of the time of this writing.

This is the 5th 3D printer after

  • XYZ Da Vinci 1.0
  • Wanhao Duplicator i3
  • Tevo Tarrantula
  • Prusa i3 MK3S

I wanted to build a CoreXY printer and didn’t want to wait for the one Prusa announced lately.

Some days before the review on Teaching Tech I ordered the printer on Aliexpress. After this review, I expected to have a lot of fun with it. 🙂

Building this printer was easier than the build of my prusa printer. But I soon recognized I have to change many things:

  1. Replaced belts with fiber inforced ones. They can be better tensioned.
  2. Replaced hotend with a E3D V6 as the original one clogged to often and I want to use my V6 nozzles. https://www.thingiverse.com/thing:4265612
  3. Repaired path of the cable chain: https://www.thingiverse.com/thing:3390159
  4. WIP: Repair belt path:
    1. straighten it
    2. replace most of the belt pullies with GT2 22 M5 versions, to reduce rattle
    3. replace the construction of the front GT2 pullies with a more stable ones
  5. WIP: Repair z-axis: the two motors get always out of sync. Temporary fix: https://www.thingiverse.com/thing:4274159
  6. ToDo: Replace filament runout sensor as he is eager to eat my filament and doesn’t like to let it to the extruder. 🙂
  7. ToDo: Replace control board, as it isn’t running nice with ocoprint and the data from the bed leveling doesn’t seem to be taken into account when printing. The board doesn0t use marlin and can not be flushed with it.
  8. Support was not really helpful.

… to be continued

Easter Egg Painting -> easter bunny 2.0

There are so many projects, I would like to do and there is little time to make them all…

One of these projects is the eggbot, designed by Evil Mad Scientist.


I found a DIY version on thingiverse and built it with my daughter: https://www.thingiverse.com/thing:1683764

And hooray….

My daughter screwed all the parts together, organized the wires and made some nice drawings (better, than I could do).

webthings (mozilla iot)

Did I get it right?

Sometimes you rub your eyes and think, did I really get it?

This happened to me when I looked at mozilla iot aka webthings.

What is mozilla webthings really? You get software, where you can integrate different IOT systems (e.g. zwave, mysensors…) and have a UI where you can define rules.

I digged down to the api and didn’t find anything about security….

There are example sketches for esp8266 or esp32 to implement webthings that don’t need a gateway to webthings. When looking at the source code, you rub your eyes and ask:

Where is the enxryption of the communication channel (e.g. https)?

Where is the authentication (e.g. basic auth, or at least key hashed requests)?

Maybe I am blind (or I am getting to old…) … investigate yourself… 🙂

Comments are welcome…

Project: Evaluation of CO2 sensors

some sensors still in calibration phase

In my home automation system I use CO2 sensors from Netatmo and some MH-Z14A based arduino nodes.

I really like, that the Netatmo sensors work for about a year on battery. But they can only be integrated with a cloud api into my home automation. This has led to one interruption of several hours in the past, when the service was down. As I regulate my heating with the measured data of these sensors, this was problematic. 🙂

What I am missing with the battery powered Netatmo sensors, is a led indicating air quality.

To remove the dependency of the cloud api, I decided to build my own sensors. But before I order more MH-Z14A sensors, I want to make an evaluation.

Caution: This article is about the experiences I made in my setup with the sensors I have and with the (maybe buggy) code I wrote. It may be, that you can not reproduce my findings. 🙂

evaluate CO2 sensors for Netatmo replacement


  • I don’t want to be dependent on cloud
  • I wan’t a led indicating air quality with every sensor


  • prototype with every sensor
  • graphs of measurements made with different sensors
  • decision for one sensor


  • buy samples of different sensors
  • build a prototype with all sensors
  • make measurements, store them in influxdb and make graphs with grafana
  • evaluate the measurements


  • 20190409
    • Prototype built with MH-Z14A and CCS811
    • API Endpoint with node-red configured to store data in influxdb
    • first dashboard in grafana implemented
    • other sensors ordered
  • Progress 20190424
    • MH-Z19b arrived


  • na

open items:

  • na


The CCS811 seems to reset sometimes (no values for several minutes and then starts with 400ppm). I will add a pull up resistor on the I2C bus.

CCS811 is quite complex to handle. It has a MCU and you can make firmware updates. The library from adafruit is incomplete, it doesn’t support baseline-functions, which you have to use. I changed to the sparkfun library.

CCS811 didn’t show usable results in mode 3 (measurement every 60s). Now trying mode 1 (every 1s) with a moving average over one minute.

MH-Z19b arrived