[Stringing on one part of many in a print?]

I recently printed about 12 little shot glass sized parts in UM Clear nylon. All print settings were default with the exception of having the build plate adhesion turned off. Only one out of the 12 parts had stringing at one spot all the way up. It is of very little concern due to the use of the part, but i was curious about the cause. Anyone had this type of localized stringing on one of many parts printed at the same time? Any recommendations?

The highlighted part on the build plate below is the one that had the stringing issue.

[UM3 + Cura 2.4 Nozzle moves away then back into initial prime extrude]

I had the same issue.  Updated the firmware about a month ago which has solved the problem for me.

 

we updated our firmware about 2 weeks ago things were better but still have to at least watch both nozzles go through prime sequences. It happens a lot less with new firmware and cura 2.5 beta but when it does happen it ruins the print.

[UM3 + Cura 2.4 Nozzle moves away then back into initial prime extrude]

G0 F5000 X162 Y16 Z0.27

That's 1cm from the starting position of the prime! That should never catch the prime poop.

I can't imagine that that gcode catches the prime poop.

 

You don't have to imagine it catching the prime poop, watch the video above

The problem is it goes from Z2 to Z0.27 before before it goes from Y6 to Y8 or so.

Cura 2.5 helped but it still sits down and catches the prime pile with the fan shroud sometimes. It mainly does this on the nozzle 1 prime pile.

[UM3 + Cura 2.4 Nozzle moves away then back into initial prime extrude]

It was definitely worked on, I just loaded 2.5 beta today. Now it comes down and squashes the prime prime pile with the carriage.

Here is the unmodified GCODE around the prime extrude for nozzle 1 which in the case of this print was after the prime pile and brim was printed in PVA from Nozzle 2:

(Please note I moved the Nozzle 1 prime location so that I could see it better on the camera)

T0

G92 E0

M109 S245

M104 T1 S0

G0 F5000 X213 Y207 Z0.27

G0 X162 Y6

G0 F15000 X162 Y6 Z2

G280

G1 F1500 E-6.5

G0 F5000 X162 Y16 Z0.27

It is the last line shown above that moves the carriage in the Y direction 10mm from the prime pile and sits the carriage back down in it. if it just would have gone to X112 before sitting back down to Z0.27 it would have been fine, It'd be even better if they put a 2 second dwell in there for the nozzle have time to ooze onto the build plate.

So the Gcode would then be:

T0

G92 E0

M109 S245

M104 T1 S0

G0 F5000 X213 Y207 Z0.27

G0 X162 Y6

G0 F15000 X162 Y6 Z2

G280

G1 F1500 E-6.5

G0 F5000 X112 Y6

G0 Z0.27

G4 P2000

I CAN edit the GCODE but it would be awesome if there was no edit required to trust printing without having to run to the machine if a prime pile gets picked up.

Also adding a short dwell after the nozzle 2 prime would be awesome too. I even added a move to z30 then a -50mm Y move then move to z2.27 with a 2 second dwell, this worked awesome to get the ooze of PVA to attach to the build plate.

[Ultimaker 3 extended PVA not working]

So you are wanting to print something that is only PVA?

[UM3 + Cura 2.4 Nozzle moves away then back into initial prime extrude]

We are having an issue of the nozzle moving back into the prime piles and picking them up and dragging them around. This has been happening with both nozzles sometimes on the PVA even when printing a single material part without PVA. I have had some luck modifying the GCode to move away from the prime pile then come back down close to the build plate to let any extra get attached to the build plate before moving on. However, if i miss any part of the gcode mod it picks up the prime pile or rolls it around while printing causing other issues or making it so we have to watch the print for the first 10-15 mins.

It happened even more often before i moved the nozzle 1 and nozzle two prime piles to opposite sides of the build plate. Every now and then it would prime nozzle 1 just fine then when it went to prime nozzle 2 it would pick up the nozzle 1 prime.

The link below shows the nozzle moving back and picking up the prime pile.

 

It would be nice if Cura resolved this or maybe another UM3 firmware update? It is frustrating to have to edit the Gcode for every print, esp since it is different depending on whether we use a brim or not.

-Danny

[Observation on too great a difference while autoleveling]

I noticed that if you have adjusted the bed height manually too high with the thumb screws the spring pressure isn't enough to give the right feed back(?) for auto-leveling. We had an issue where every print was giving the "Difference detected too great..." error until we lowered the plate significantly with the manual thumb screws and re-leveled the build plate.