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How can I change the Z axis length to 320mm in firmware?  

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Nick Cent
(@nick-cent)
Active Member
How can I change the Z axis length to 320mm in firmware?

Hi,

I have just finished building an original prusa mk3s on a 320 Bear frame. The only change is the frame - everything else is MK3s.

My goal is to be able to follow on the updates of the original Mk3s while having this taller and more rigid frame. What do I have to do to the firmware to pass the XYZ calibration? 

This topic was modified 1 year ago by Nick Cent
Posted : 13/04/2021 5:05 pm
Nick Cent
(@nick-cent)
Active Member
Topic starter answered:
RE: How can I change the Z axis length to 320mm in firmware?

No one? 

Posted : 27/04/2021 7:53 pm
Baklin
(@baklin)
Reputable Member
RE: How can I change the Z axis length to 320mm in firmware?

Looks like you can temporarily use a bear firmware to pass xyz calibration. Or an older prusa firmware. 

 

https://guides.bear-lab.com/Wiki/Bear_FAQ#Section_I_am_using_the_Bear_MK3S_extruder_and_I_cannot_pass_XYZ_calibration_How_can_I_get_it_to_calibrate

Posted : 27/04/2021 7:59 pm
egar
 egar
(@egar)
Estimable Member
RE: How can I change the Z axis length to 320mm in firmware?

@nick-cent

I don't have the Bear upgrade, but I looked into it briefly. I believe you have to use custom Bear firmware for the initial calibration.  Check out the FAQ or the Github site.

Posted : 27/04/2021 8:08 pm
Nick Cent
(@nick-cent)
Active Member
Topic starter answered:
RE: How can I change the Z axis length to 320mm in firmware?

Thank you both for taking the time to look into this. I have replaced the smooth rods only, to pass the calibration only - and it worked. I have of course tried the Bear calibration firmware, but this one, too , expects the 220mm Z axis length, so not a solution unfortunately. I thought the Bear calibration firmware was for unlimited Z length, but nowhere near. Then, I looked into the Zaribo firmware, on their website (Zaribo), which they have 3 versions for each Z axis version they do (220/ 320/ 420). But, apparently the motor direction is opposite; something I can fix easily  within the Arduino IDE, but I haven't tried this one yet. For now, it's working just fine, running the latest prusa firmeare 3.9.3, but limited to 220 mm of Z axis length. 

I wanted to just modify the Z_MAX somehow in the formware, but it is not easy. It is in multiple places for the calibration and not only. 

This post was modified 1 year ago by Nick Cent
Posted : 27/04/2021 11:03 pm
App
 App
(@app)
Active Member
RE: How can I change the Z axis length to 320mm in firmware?

If you haven't already, download Arduino IDE 1.8.13 www.arduino.cc/en/software, then get the latest Prusa Mk3 firmware over at github.com/prusa3d/Prusa-Firmware, Open this file in IDE, edit Zmax to suite your machine now Z=320mm, recompile firmware, flash to printer. Unless you have previous experience with Arduino and/or code, it's a fairly in-depth and multi-step task, but you can do it. 

Posted : 02/05/2021 1:07 am
App
 App
(@app)
Active Member
RE: How can I change the Z axis length to 320mm in firmware?
Posted by: @nick-cent

. But, apparently the motor direction is opposite; something I can fix easily  within the Arduino IDE

Or use Zaribo firmware and just swap your wiring to stepper coils for opposite rotation:

Motor moving the wrong direction

To get the motor moving in the right direction, is actually does matter which coil is which and what the polarity of the coils are. However, if they're wrong, the motor just turns the wrong way, it's easy to fix that by swapping wires. Pick one of the following in order to reverse the stepper's direction:

  1. Switching the polarity of either (one) coil, like changing ABCD to BACD or ABCD to ABDC.
  2. Swapping the coils, like changing ABCD to CDAB.
  3. Stepper direction can also be reversed in the firmware.
  4. Plugging the plug in backwards (in case your electronics' plugs allow that). This swaps the coils, and reverses both coil A and coil B. Thus the effect is to change the direction 3 times, which gives a net effect the same as changing the direction once. Only few electronics allow that, because you have to figure the right way not once, but each time you connect the stepper.
Posted : 02/05/2021 1:16 am
towlerg
(@towlerg)
Noble Member
RE: How can I change the Z axis length to 320mm in firmware?

Pretty sure I've misunderstood what yo want but the literal answer is to amend the variable Z_MAX_POS in Configuration.h

Posted : 02/05/2021 3:20 pm
Nick Cent
(@nick-cent)
Active Member
Topic starter answered:
RE: How can I change the Z axis length to 320mm in firmware?

Thank you for the info. I have changed my plans and I will revert the Z axis length to 220mm or whatever the original prusa is, for several reasons. I want this printer to fit inside the LACK enclosure and I'm going to add the mmu2s to it, so I want to able to use the firmware I need with ease, and not have to mess with it everytime before I install it. Also, never have I needed to print something taller than 220mm. Being it a 1:1 clone will make things much easier with Marlin and Prusa firmware. I am building another 3 printers with Duet boards. One of them is the Ender 3 ,which will accomodate the longer aluminum extrusions and z motors with screwwleads of this aforementioned modification, and easily enough will become a taller Ender 3 with zaribo Z steppers w/ 320mm screwleads.  

If someone wants to have a taller Prusa i3 mk3, then they should look into the Caribou firmware, as well as, the Zaribo firmware, for a ready hex file for 320 and 420 mm verisons. I stopped working towards the taller prusa, so haven't done the editing of the .h files, but from what I read, it is the Z_max_pos length that need to be found and replaced within the code text. Nevertheless, this could change from version to version and I don't want to have to keep up with the next solution and such.   

Posted : 02/05/2021 7:00 pm
towlerg
(@towlerg)
Noble Member
RE: How can I change the Z axis length to 320mm in firmware?

Don't have any prove but I doubt if something as basic as Z_MAX_POS is going to change. From the little I know of Marlin most config version differences are additions.

Posted : 03/05/2021 9:00 am
App
 App
(@app)
Active Member
RE: How can I change the Z axis length to 320mm in firmware?

@towlerg

I think Nick Cent was referring to the process of maintaining the extended Z=320mm  with each new firmware release. When Prusa releases a new version, will have pull it from GitHub(which will be Prusa Z default, so upon flashing to Mk3 overwrite 320mm back to 210mm), open file in ArduinoIDE, edit Zmax from standard 210mm to 320mm, recompile, just to be able to flash latest firmware.  Compared to Prusa's updating firmware very easy .

From doing this twice myself, unless you have a very good reason to extend an axis(making $ for business etc) it's not worth it.  I converted an Mk3s to what I call my PrusaTall 1000mm on the Zaxis and kept standard 250mmx210 print bed. It's been running on 2yr firmware b/c never have time to recompile to newest firmware, whereas by 5 other Mk3s and Minis are always up to date.

Posted : 04/05/2021 2:54 pm
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