New Cura version has G92 extruder nonsense in "End G-Code"

[grimsrudjk 0]

So after installing the latest version of Ultimaker Cura, Cura decided to corrupt all of my printer settings from the previous version, and I had to start over completely from scratch. Whatever, I understand this happens sometimes, but what I really didn't understand was why my already difficult-to-load filament kept retracting completely out of the extruder every time a print finished. Finally, I uncovered this in the End G-Code:

 

M104 S0

M140 S0

G92 E80

G28 X0 Y0

M84

 

Can anyone explain what the rationale for this was? G92 is used to reset an origin. What business does it have being used to command an extruder like this? Why couldn't whoever came up with this just use the G1 command if they wanted to add a routine extraction? And why on Earth was this set by default to 80mm? Why would anyone think that this was a good idea to include? Can anyone think of any conceivable situation where automatically retracting 80mm at the end of a print would be something an operator would actually want? I'm just asking because I had nothing but nonstop printer problems all week and this was just the icing on the cake. 

Edited April 14, 2020 by grimsrudjk

[djgraff209 0]

I had just asked about this I think shortly before yours in regard to the Anet A8 profile.

 

I went out to GitHub to look at the history on this:

 

https://github.com/Ultimaker/Cura/blob/92691f68b6e969b07519a3dd91cff98796a765e4/resources/definitions/anet3d_a8.def.json

 

Long and short of it there is a better setting:

M104 S0
M140 S0
G92 E0
G1 E-10 F2000
G28 X0 Y0
M84

So  - G92 E0 sets the extruder position to 0, then G1 E-10 F2000 runs an extrusion of -10mm and sets the feed rate to 2000.

 

I'm going to give this a wing and see what happens - I was NOT happy with the 80mm retract - pulled the filament out of the extruder throat and globbed it under the hobbed gear. Had to take the thing apart to clear it.

[grimsrudjk 0]

So glad I wasn't the only one to experience this!! I had to take my extruder apart four times in a single night to fix this every time it happened. I couldn't for the life of me figure out what line of code was causing it. As an aside, I also had no idea that this sort of low-level Gcode could be examined in Cura's Github. Thanks for sharing that. 

 

Just an FYI, I was recently told that more optimal printer settings can be found on the SD Card that came with the printer. You can take those settings and merge the ones you want into your current Cura printer profile. I've never actually plugged in that SD card, only because I didn't know what sort of potential nasty malware might be lurking on it. If I had purchased a more reputable branded printer I probably wouldn't have hesitated to take a peek at what was on it. 

Edited April 17, 2020 by grimsrudjk