Nozzle crashing into extruded filament at beginning

[Dana 2]

Hi All, I have just tried make a fast print profile and found that for the first time at the start of a print it extrudes in the front left corner as usual but then the build plate raises crashing the nozzle into the extruded filament before moving to the start of the print taking the coil of extrusion with it.

 

This has never happened before and unfortunately just before I thought of asking on the forum I deleted the profile, I still have a GCode for that print if it helps isolate the issue, the profile had quite a lot of changes to the settings!!

 

also I only have the three profiles (Extra fine, fine and normal) is there anywhere I can download more? a google found nothing out there

 

thanks

 

Dan

Edited March 19, 2020 by Dana

[mechamecha 64]

I'm having the same issue with my Ultimaker 2. The printer does a nozzle purge first, then it lowers the nozzle straight down into the purged filament and drags the mess into the print.

UM2_start_gcode_problem.3mf

[bagel-orb 61]

The sequence is hard coded in the firmware of the machine. What you can do in Cura is disable The prime blob altogether.

 

The downward movement of the nozzle is not exactly into the blob, but next to it. It's supposed to wipe the blob onto the bed.

[geert_2 560]

11 hours ago, mechamecha said:

I'm having the same issue with my Ultimaker 2. The printer does a nozzle purge first, then it lowers the nozzle straight down into the purged filament and drags the mess into the print.

UM2_start_gcode_problem.3mf 141.76 kB · 0 downloads

 

For my UM2,  I made a nozzle scraper from steel spring wire, after an idea from another user. The very hard inox wire that is also used in dental appliances. In 99% of cases, this works perfectly.

 

Since it is a spring, it moves away when the nozzle moves over it. It doesn't cause any damage.

 

 

 

 

 

 

 

 

[Dana 2]

thats a nice solution but this has only happened to me once ie the last print, the firmware has not been updated on the printer, the only possible difference is new Cura and normally I use Merlin settings but didnt this time, this time I used a configured profile, 

 

is there anywhere I can download profiles?

[mechamecha 64]

6 hours ago, bagel-orb said:

The sequence is hard coded in the firmware of the machine. What you can do in Cura is disable The prime blob altogether.

 

The downward movement of the nozzle is not exactly into the blob, but next to it. It's supposed to wipe the blob onto the bed.

 

Thanks for the reply. What you say is certainly what I've observed with UM3, with which I have had no problems. For me, that prime blob is simply squished down by the print head and I haven't noticed it dragging at all.

 

The problem is with UM2, and I don't think it's a firmware thing, because this wasn't happening with Cura 4.1. Just started using 4.5, which is when it started being an issue. It does seem to drop the nozzle straight down into the middle of the purged filament.

 

Another problem I've noticed with Cura 4.5 is that settings sometimes mysteriously vanish when I switch from one printer config to another (e.g., UM3 to UM2).

[bagel-orb 61]

Settings always vanish when switching between printers. Settings are often printer-specific. This is how Cura was designed; it's supposed to work like that.

 

So you are saying that the prime blob was already there in 4.1 and the only difference is that in 4.5 it moves down into the prime blob? Or is the whole prime blob new in 4.5?

[mechamecha 64]

Prime blob has never been an option for UM2.

 

Regarding the vanishing settings, I'm not talking about printer-specific settings. Things like support settings are sometimes disappearing. To get them back I need to restart Cura. Or go into settings and deselect, then reselect.

[mechamecha 64]

Another thing I noticed was that when changing certain settings after slicing in Cura 4.5, it doesn't give you any option to reslice like it should. For example, support roof settings. It will continue to just show "preview" and "save to file" options. I have to change another setting, then set it back to its original value to reslice.

[Dana 2]

Dear mechamecha can you please start your own thread with your own specific questions? you have hijacked this and its moving off topic

 

thanks

[mechamecha 64]

Sure. Doesn't really look like there's a legit solution for the filament dragging problem, though. I was the first one to reply to your original post after three days, reporting that I was experiencing the same issue.

[bagel-orb 61]

I'm not sure anymore how I should help. I've said what I can, but mechamecha responded, but that driften off topic and now I don't know how to get back on topic.

[mechamecha 64]

Sorry about that. I started my own topic about the unrelated issues.

 

But the original issue remains: Cura 4.5 drops nozzle straight down into purged filament, causing it to be dragged into the print. Original poster hasn't specified which printer they're using, but I'm experiencing this with a UM2 (as is geert_2 it seems). Not firmware related, because I can confirm this didn't happen with 4.1; it only started when I switched to 4.5. Also not a "prime blob" issue, because that's never been an option for UM2.

 

If anyone still believes I'm "hijacking" this thread, I'll refrain from posting here and start my own topic concerning this issue...

[JackChen1976 0]

I'm having the same problem as Dana had.  This happened after I updated the firmware to my UM 2+ yesterday.  

Before update, the nozzle's initial move was ramping down to start the print after priming.

 

;FLAVOR:UltiGCode
;TIME:12740
;MATERIAL:33484
;MATERIAL2:0
;NOZZLE_DIAMETER:0.4
;MINX:12.304
;MINY:7.123
;MINZ:0.2
;MAXX:212.283
;MAXY:212.483
;MAXZ:10.95
;Generated with Cura_SteamEngine 4.5.0
M82 ;absolute extrusion mode

G92 E0
G92 E0
G10
;LAYER_COUNT:66
;LAYER:0
M107
G1 F600 Z1.2   <-----------------------------Nozzle plunges down to plate (into the blob) right after priming.
G0 F3461.5 X40.993 Y43.23 Z1.2  <-----start of the print
;TYPE:SKIRT
G1 F600 Z0.2
G11
G1 F1500 X41.74 Y42.533 E0.08173
G1 X42.298 Y42.022 E0.14226