Lift head setting

[Falconator 0]

Hi, been 3D printing for a while and have moved to Cura as my go to slicer, to make my prints better on small layers I have turned on the Lift Head function in order to allow the PLA that I print with to solidify before the next layer, however this then results in ooze from the print head which can lead to under extrusion in subsequent layers. There is the option for retract when Z-hopping but not for lifting the head or are these two things the same, if I enable retract for Z-hop will it view the head lift as a Z-hop and retract the filament?

If this is not the case could this be considered as an option for future versions of Cura, either combining the setting of retract for Z-hop which will also cause a retract on head lift or a bespoke setting for retract on head lift?

[gr5 2,167]

I'm pretty sure it *does* retract when it does "lift head".  But retraction only lasts for a second or so - enough time to jump to a new part of the print.  But lift head will often sit in the air for 3 seconds - plenty of time for a micro sausage to come out and then get deposited on the print when it starts printing again.

 

The only good solution I've seen is to print a tower next to the part so that the print head can go to the tower and print a little bit to give the print time to cool (just a few seconds is usually enough.  Keep the tower in a position such that when the head goes to it the fans blow on your part (if possible).

 

Instead of a tower, sometimes I print 2 or 3 or even 7 of the same part.  While printing one parts the other parts all have time to cool.

[darkconsole 0]

On 2/28/2021 at 5:55 PM, gr5 said:

The only good solution I've seen is to print a tower next to the part so that the print head can go to the tower and print a little bit to give the print time to cool (just a few seconds is usually enough.  Keep the tower in a position such that when the head goes to it the fans blow on your part (if possible).

 

Instead of a tower, sometimes I print 2 or 3 or even 7 of the same part.  While printing one parts the other parts all have time to cool.

 

this is the smartest dumb idea i've seen yet for dealing with this. on my small parts lift head has been extremely necessary so far. probably going to do the tower idea. make a little square extrude straight up next to my main model. i was spending lots of time trying to include bedwipes here and there but that requires it to go all the way back down then up again. this is way better.

Edited February 3, 2022 by darkconsole

[manugaldeanoruiz 0]

Hi everyone! I've doing that (multiplying the same part to make the layer last longer) but sometimes it is not possible. The real problem is not the stringing or oozing, but the position where it happens. "Lift head" only moves up the head 3mm, on the same X and Y position, so the oozing falls on top of the part. /facepalm/. Is there a way to specify a relative position to move?

[GregValiant 1,245]

There is no "Park Head" option for Lift Head.  It could be done in post process but exactly how it's done raises some questions.

• You mentioned a "relative" park distance but would 5mm be enough?  The nozzle may well still be over the part, just not quite where it was.  An absolute park position might send the head from the right rear to the left front.  That might take longer than the pause.
• There could be some drool hanging from the nozzle.  Should it drop back down in the Z and wipe on the side of the part, or go back over the part and stick it where the Z drops back down?  That would seem to be right back where you started.
• Should the time spent in travel be subtracted from the pause time?  A bit more time wouldn't hurt.

 

 

[GregValiant 1,245]

Attached below is a collection of 5 post processors.  The last one (todays work of art) is Lift Head Parking.  Unzip and put the "LittleUtilities.py" file in your configuration folder, the "scripts" folder.  On my Windows computer it's "C:\Users\...name...\AppData\Roaming\cura\5.4\scripts.

It figures out the shortest orthogonal move to get off the part and goes there, waits for the G4 pause, and then goes back, drops down, and the print continues.  There will likely be a booger.

In regards to Cura's Lift Head retractions:  If there is a normal retraction just prior to the Lift Head movement, then Lift Head does not include it's own retraction.  If there is no retraction in front, then Lift Head will include a retraction.  In this snippet a retraction was called for because there was none ahead of the move.

G0 F9000 X199.375 Y36.033

;Small layer, adding delay
G1 F2100 E3451.70922
G1 F600 Z13.4
G0 F9000 X206.461
G4 P8132
G0 F9000 X199.375 Y36.033

The two bold G0 lines were added by the post processor LittleUtilities / Lift Head Parking.  Rather than moving all the way to a corner it just moves straight to a point over the skirt/brim/raft.

 

LittleUtilities.zip

[manugaldeanoruiz 0]

Amazing. Thanks a lot man. Im printing with PC and it was giving me a headache. I mainly print gears and mechanical stuff for industry, and most of them are quite small (PC, PCABS, PA). So i end up with a lot of parts just for the sake of having one well printed. Im gonna try it right now. Thanks again.

[GregValiant 1,245]

You're the test case so let me know what you think about it. 

Edited July 18, 2023 by GregValiant

[manugaldeanoruiz 0]

On 7/12/2023 at 7:01 PM, GregValiant said:

Your the test case so let me know what you think about it. 

It goes quite well. The printhead moves only on Y axis, all the way to the edge of the brim, wherever it may be. What i havent tried, is to put two objects, on different positions on Y axis, to see if the printhead moves to the absolute further position over the edge of the brim on Y axis, or if it is relative to the current X position and just goes to the actual edge of the brim (i dont know if that makes sense)

[GregValiant 1,245]

I used the MAXX, MAXY, MINX and MINY that Cura puts into the front end of a gcode.  The nozzle will go to either the Y or X skirt/brim based on which it is closer to.

With two models, a skirt would go around both.  So the math in the script might go the long way across a model because the skirt/brim might be closer that way than traveling all the way to the other side.