Prusa MK4 & Octoprint  

RE: Prusa MK4 & Octoprint

Posted by: @yeungster

I've noticed a difference in behaviour recently with manual filament colour changes mid-print but I'm not sure whether this was introduced with the latest software updates for the MK4 or whether this is unique to Octoprint (not had a chance to test yet).

Previously my manual colour changes worked flawlessly when printing from USB stick. Remove old filament, load new, purge, confirm colour is correct, resume printing from place it left off - all good.

What I'm experiencing now is exactly the same as above, but immediately after confirming the colour is correct (after purging), the nozzle zooms to the place it left off, but it also purges out filament as it starts printing. Thankfully I've managed to save it the last couple of times by swiping at the extra poop but is this unique behaviour to Octoprint/printing via serial or has this crept in with the latest Prusa software updates?

Is there any way around this? I followed the official Prusa Octoprint instructions for adding custom g-code elements, so no idea where to look next.

Thanks
Pete

Just tried the filament change using Prusalink and it does the same extra purge as, on location, just as its resuming.

I'm convinced it never behaved this way preciously. Was this intentional?

RE:

The extra purge has been an issue for as long as I can remember (Prusa Mk1 era) (When we were using Slic3r as the standard slicer(Predecessor to Prusa Slicer))

What I do, 
is go through the normal steps of filament change until the new filament purges the old filament, 
At this stage I DO NOT PULL THE WASTE OFF. 
instead, I Hold on to the waste with pliers or my fingers. 
and instruct the printer to continue. 
As the nozzle moves back to the model, the annoying extra purge is extruded, but it stays connected to the waste that you are holding, ad pulls off the nozzle. 

regards Joan

RE: Prusa MK4 & Octoprint

Thanks Joan. Great suggestion. I'll do that.

I must be going crazy 🤪. I would have put money on it. Good job i didn't 😆.

• Thanks

RE: Prusa MK4 & Octoprint

If I had a pound for every time I have answered the extra purge messages, I would be a more wealthy woman! 
Lol

https://marlinfw.org/docs/gcode/M600.html (M600 code description)

Your next question, is likely to be, 
"Why does the Printer go back to the last position, it printed, after the colour change, and leave a 'Beauty Spot' there? before continuing with the print...)  

answer, whoever wrote the Colourchange script, didn't address that issue... 

there is an additional parameter in the M600 Action command structure  
M600 N    

See Information 
https://reprap.org/wiki/G-code#M600:_Filament_change_pause

the 'N' parameter is supposed to stop the printer returning to the previous position, but it does not seem to be implemented in Prusa Firmware. 

When I am using M600, for colourchange by layer height, I do the colour change one layer higher than normal, this results in the last print position being beneath the colour change start position, and therefor not being visible, after the colourchange. 

If this is not possible, I put a piece of paper over the print whilst the nozzle is in the colourchange position, and when the printer goes back to the last position, it dabs on the paper, and I whip the paper out taking the 'beauty spot' with it
Not ideal, but it's a functional option. 

regards Joan

RE: Prusa MK4 & Octoprint

Posted by: @kevman

does the filament runout sensor work with Octoprint and the MK4 ?

OctoPrint have several plugins for filament runout sensor. I have been using OctoPrint for 3 years on an Ender 5 plus without bothering with the sensor but I did connect the original Ender sensor to the OctoPrint PI today and it seems to work fine (did not have time to do a real test during printing, I'll do that tomorrow). Only needed to make a cable with the correct plug in the end... Using "Filament Sensor simplified" plugin.

The Ender 5 use a micro switch but I believe the hall sensor in MK4 should be usable directly in the RPi.

RE: Prusa MK4 & Octoprint

With the firmware versions in the beginning the printer just kept on with the motions without filament on filament runout when using OctoPrint. But since firmware version 5.1.0 the MK4 pauses and beeps, you have to change the filament via the screen on the printer and the print continues. You should read this posting:
https://forum.prusa3d.com/forum/english-forum-original-prusa-i3-mk4-general-discussion-announcements-and-releases/5-1-0-firmware-for-original-prusa-mk4-is-out/
And search in the post for the heading "Improved Octoprint support". Follow the steps there to enter some G-Code scripts into the configuration of OctoPrint to make the filament runout sensor work with OctoPrint.

RE: Prusa MK4 & Octoprint

I blindly ordered my MK4 without thinking much about OctoPrint, because I thought it would be 1:1 the same experience (or even better).

When I connected it and saw the OctoPrint icon on the screen I cheered up and was happy. After some time I realized that it's still in progress and incomplete, no info on the screen is such a bummer, or the missing USB drive reading (I printed the MMU3 parts and didn't want to mess with OctoPrint yet).

Great to see that at least Prusa acknowledge and wants to further support / improve integration with OctoPrint, but honestly I was expecting this from the start up (like many others). I keep my fingers crossed that this year more improvements will arrive. <3

And MMU3 support is another level. 😀