Firmware Setting -> Z_MIN_POS 0.23  

Re: Firmware Setting -> Z_MIN_POS 0.23

By using bussines card to calibrate you are actualy putting something between glass and nozzle. That is 0.23 (thickness of bussines card ) . When you do the calibration in all four corners then you can just start printing with the slicer you downloaded from here. If it is level, it will work 😀 .

Re: Firmware Setting -> Z_MIN_POS 0.23

Thanks for the reply.

That doesn't make sense to me so modified the firmware such that when the z endstop is set the value goes to zero. Printing the first layer much better now.

Regards,

Angus

Re: Firmware Setting -> Z_MIN_POS 0.23

Hi Angus

Just received my Prusa I3 original this morning.

I am concerned about this issue; I have already emailed Jakub (support) twice regarding this and another issue I raised (regarding KISSlicer settings) but he has unfortunately "forgotten" to answer on both occasions.

Would it be possible for you to give simple step-by-step instructions as to what is required to amend the firmware? I already have the Arduino IDE installed with the RAMBo as output device.

Many thanks in advance

Peter

Re: Firmware Setting -> Z_MIN_POS 0.23

Hey Peter,

The mod was simple, I used the following process,

1. Install the Rambo add-on available from the PR downloads section
2. Set the IDE to use that board
3. Load the marlin firmware and find the configuration.h file
4. Find the Z_MIN_POS value in there and change from 0.23 to 0
5. Save
6. Go to File -> Preferences and select the option to show verbose output during compilation
7. Select Sketch - > Verify / Compile
8. When finished one of the last compilation comments will show you the location of the .hex file created
9. Load the Firmware updater from driver version 1.6.0. You can try version 1.6.1 updater but I recon there is a bug in there as it keeps complaining about spaces or something. I follow the same process with the 1.6.0 version and all works.
10. Update the firmware like normal.

Angus

Re: Firmware Setting -> Z_MIN_POS 0.23

Hi Angus

Thanks for this. I hope to be printing tomorrow, so will try that if necessary.

Peter

Re: Firmware Setting -> Z_MIN_POS 0.23

Hi Angus

Just re-built and flashed the firmware. As you say, simple, but it should not have this issue in the first place.

I also found that the firmware crashes and reboots when you press the load/unload filament or move the extruder when the temps are below 190 degrees. It should not crash, but I guess this is a "last resort measure...

Many thanks for your help.

Peter

Re: Firmware Setting -> Z_MIN_POS 0.23

Hey Peter,

Good to hear that it reflashed for you. I agree with you that its not the right way to do it but as I noted previously, its not my name on the printer so not up to me to define how its done. If it was me I would have each axis zero correctly and then put an offset in Slic3r at the start of the g-code. That is how they did it for the 3mm version if I recall correctly and it was a great way to do it. That way when your kids destroy the card supplied with the printer (as my kids did) you can use anything to calibrate and just adjust the value in slic3r.

With regards the crashes, I haven't had any issues with that.

Angus

Re: Firmware Setting -> Z_MIN_POS 0.23

Hi

I also want my z axis to Z_MIN_POS 0 but can someone describe step by step from the beginning. I'm new to this but want to try 🙂

Best regards Peter

Re: Firmware Setting -> Z_MIN_POS 0.23

Hi Peter

I don't think I would advise doing this. The first layer needs to be 0.25mm or greater to ensure a good stick and therefore having Z_MIN set to 0 or 0.23 mm makes no difference.

The only reason I have set Z_MIN to zero is to match my other printer and I occasionally slice with a first layer of 0.2mm for that and therefore it is possible to use that gcode for either printer.

If you really do want to do it, here's a brief "how to" (using firmware V2.2.1).

1. Download the latest Arduino IDE from Arduino.cc
2. Open the IDE, open file/preferences and set additional boards manager to the RAMBo repository: https://raw.githubusercontent.com/ultimachine/ArduinoAddons/master/package_ultimachine_index.json
3. Open Tools/Boards/Boards Manager and install the RAMBo board.
4. Close the IDE.
5. Unzip the Prusa firmware source code and follow their instructions for your board.
6. Open Configuration_prusa.h in a text editor (Notepad++) and find the line:
#define Z_MIN_POS 0.23
7. Remove the ".23" from the end of the line
8. Save and close the file
9. Double-click the Firmware.ino file - this will open the Arduino IDE
10. Connect the printer, compile and upload.

Peter