material going out of nozzle while heating up or on idle and first layer problem  

Re: material going out of nozzle while heating up or on idle and first layer problem

reverse order,

oozing is pretty much expected...

some folk change the start gcode to heat the nozzle to say 170C (for general PLA) do the mesh bed levelling then heat to say 215C to start printing, this reduces the blobbing on mesh bed levelling...

first layer calibration.

the Prusa LCD option, works but is not particularly easy to fine tune!

Try Jeff Jordan's Life adjust My Way https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html#p99776
the V6.1 files are on the first page...

If you get spaghetti your live Z is too high, too small a negative number,
if you get a smooth surface live Z is just right,
if you get ripples and a rough surface, your live Z is too low (too big a negative number

regards Joan

Re: material going out of nozzle while heating up or on idle and first layer problem

I've only had my printer for about a week, but when I've started prints, I notice the extruder starts oozing during the calibration at the start of the print. By the time it does the smear at the bottom corner to clean the nozzle, there's maybe 3/4" hanging off. If I'm lucky, this drags behind and gets pulled away. But about half the time it stays attached, and then when the perimeter ring is drawn around the model footprint, it ends up ripping up the ring that it's just printed and I have to stop the print.

I would be very happy to see a config option where it would do the calibration first, then pause and raise the Z axis to let you manually wipe the nozzle, then jump straight into the print.

The other option, which would still be fully automatic, and might be better in general, would be to do the calibration before preheating. Check the 9 points , then move to the bottom left corner at the start of the smear and then heat the nozzle/bed. Waiting to calibrate until the nozzle is at full heat seems error prone.

Re: material going out of nozzle while heating up or on idle and first layer problem

I keep a small brass wire brush next to the printer. A quick touch takes off those oozings--no problem.
I saw/heard it recommended someplace as a standard tool to have to keep nozzles clean. Make sure the wires are brass (and not steel), so as not to scratch the nozzle. Brass is fine for harder nozzles as well.

Re: material going out of nozzle while heating up or on idle and first layer problem

Thank you for quick reply.

At first, thank you for naming that "material going from nozzle" effect - I thought that it should have some name so oozing is right one 😀

Totally agree with sean.s20 - exactly same experience, sometimes that blob is removed on first thick start line, but sometimes it's not gets to print area and I have to start again.
Wire brush is good idea, but it seems to be bit temporary solution.
So from my point of view start up procedure modification would be great (and maybe not so complicated, just change order at the beginning of print).
If there is level calibration done before heat up or starts at the same time as it heat up starts, there will less time for material to bleed from nozzle so be no or just very small line of material on nozzle at start of print.

About that first layer, thank you for advice, according to your description it seems that layer is too thin (ripples) so I'll try to rise it till it starts spagheting and bit lower it then.
I'll try that Jeff Jordan's Life adjust My Way thank you.

Re: material going out of nozzle while heating up or on idle and first layer problem

Lots of people probably know all this already, but I just was taking a closer look at Slic3r PE and the 'Printer Settings' panel. It looks Slic3r provides the gcode for print start/finish/next layer/etc. As far as I can tell it would be possible to move the mesh level check to before the heating phase. Maybe even during as was mentioned.

This is a snipped of my default Slic3r PE Start-gcode:

...
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
...

It would seem that changing this snippet to:

...
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
...

would cause to do mesh leveling before heating. My only concern with putting leveling in the middle of the heating phase is that if the bed/head were already almost to temperature then something unexpected could happen.

Re: material going out of nozzle while heating up or on idle and first layer problem

FYI I just tested this, and then also tested putting the bed level during warmup, and they both worked. If you're using Slic3r PE, give it a shot.

...
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
...

You can save it as a custom printer profile so you don't overwrite the default version. When I just tested it, it started heating and doing mesh bed leveling at the same time. As soon as leveling was done, it moved the extruder to the location where it does the initial wipe and waited for heating to finish. It oozed a little while it finished warming up, but it oozed onto the plate. When it did the wipe, the blob came off.

I still think there will be problems with the blob not coming off, and for this reason I would consider having it do one more thing. After the wipe, raise the z axis up ~10 cm for ~5s to give you a chance to wipe the nozzle if it's still messy.

Re: material going out of nozzle while heating up or on idle and first layer problem

Doing these sorts of things in startup gcode is the accepted method. Startup sequences are very personal, and I've seen several variations, each with unique advantages. Strategies related to oozing are:

Each has advantages, each takes differing amounts of time and some can be combined along with other functions. Some prefer bed & nozzle to warm up simultaneously, and are anxiously chomping at the bit waiting for each print to start. Others want careful preparation, with minimal chance of oozing, so delay nozzle warmup. Still others want the PINDA probe at a reference temperature before doing bed leveling. I personally like quiet chips to indicate progress, but cringe at the full-volume beeps. We probably do not want Prusa or anybody else dictating these sequences for us. Search around and find what techniques you prefer and you can tweak the start and finish gcode to accomplish ooze reduction and much more.

Re: material going out of nozzle while heating up or on idle and first layer problem

Prusa endeavour to provide something that works...
and they give us the tools and permissions to tinker...

after that it's up to us to look at what is important to us, and make appropriate changes.

chances are if every member of this forum were invited to address a particular issue,
some wouldn't bother, because it doesn't affect their activities,
some would wait for others to post about their successes and adopt their preferred pre packed solution.
a number of folk will approach the solution from their own points of view / experience and arrive at solutions of varying levels of success
others will pick the best bits from solutions shared, and generate another thread..

and some may try and not succeed, of these some will go back and start again, some will give up and go back to printing as they always did, and others will ask for help...

that is all part of life's rich tapestry.
what is unlikely to happen, is for two people to come up with exactly the same solution...

if we have a really good idea, and share it, that idea may then lead to improvements in what Prusa offer in the future.

Prusa ask for bug reports and suggested changes to be raised for consideration, on their Git Hub pages, a number of these reports lead Prusa developers to change the products and tools, for the benefit of all.

I find it quite exciting...

if we all thought exactly the same, life would be boring!

regards Joan

Re: material going out of nozzle while heating up or on idle and first layer problem

Here's my approach for anybody interested. This is an amalgamation of various tips and tricks I've learned lurking on these forums and others for several months, combined with some experimentation and my own stubborn preferences. This process takes longer than a simple warmup-and-go, but I am after consistency in my 1st layer. I'd rather wait for a good print to start rather than rush into 2 failures.

First I want to warm the nozzle temp up to a level that won't ooze, but that will soften in case there's a hard blob on the nozzle to avoid damaging the PEI sheet. Note that this either heat up a cold nozzle, or wait for a hot nozzle to cool to 140C for PLA. 170 for hotter materials works well. This has the added effect of cooling the PINDA down if it's hot from a previous print.

M104 S140 ; set extruder no-ooze warmup temp
M140 S[first_layer_bed_temperature] ; set bed final temp
[...]
M109 S140; wait for extruder no-ooze warmup temp before mesh bed leveling, cool hot PINDA


Note that this would be a good opportunity to raise the nozzle and give it a brush as it warms. Next, I want to warm up the bed and position the extruder to warm up the PINDA probe to a consistent temperature before bed leveling. At this point, any filament oozed from the nozzle should be soft and unlikely to damage anything.


M190 S[first_layer_bed_temperature] ; wait for bed final temp
G28 W ; home all without mesh bed level
G0 X70 Y70 Z0.10 F1000; PINDA warming position
M860 S35 ; wait for PINDA temp to stabilize
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling


After the bed leveling routine is complete, I heat the nozzle up to final printing temperature.


M104 S[first_layer_temperature] ; set extruder final temp
M109 S[first_layer_temperature] ; wait for extruder final temp


Then I like to print a prime line with a bit of a fat "blort" at the beginning to get the prime started and hopefully pull off any remaining dangling ooze. This also shoves some filament into the hot end after retracting after the previous print.


[...]
M900 K0; Disable LA for prime line to avoid extruder clicks, re-enabled in filament gcode
G92 E0.0 ; reset extrusion distance
G1 Y-3.0 F1000.0 ; go outside print area
G1 X20.0 E6 F1000.0 ; 20mm intro line @ 0.30
G1 X60.0 E3.2 F1000.0 ; +40mm intro line @ 0.08
G1 X100.0 E6 F1000.0 ; +40mm intro line @ 0.15
G92 E0.0 ; reset extrusion distance


Re: material going out of nozzle while heating up or on idle and first layer problem

I guess if we're posting our start and end g-code...

Start g-code:


M104 S0 ; turn off temperature
M140 S0 ; turn off heatbed
G90 ; use absolute positioning for the XYZ axes
M83 ; extruder relative mode
G28 W ; home all without mesh bed level
G0 Z50 ; raise Z to not heat PINDA before bed is warm
M106 S255 ; set the fan to full speed
M860 S35 ; wait until PINDA is <= 33C
M107 ; turn off fan
M104 S170 ; set extruder temp
M140 S60 ; set bed temp
M190 S60 ; wait for bed temp
M109 S170 ; wait for extruder temp
G0 X0 Y-3.0 Z0.15 ; PINDA heating position
M860 S35 ; wait until PINDA is >= 35C
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G81 ; send mesh bed leveling to OctoPrint

M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
;G28 W ; home all without mesh bed level
;G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 E8 ; Purge Bubble
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0
M221 S{if layer_height==0.05}100{else}95{endif}


End g-code:


G4 ; wait
M221 S100
M104 S0 ; turn off temperature
M140 S0 ; turn off heatbed
M107 ; turn off fan
G1 E-0.8 F900 ; retraction
{if layer_z < max_print_height}G1 Z{z_offset+min(layer_z+30, max_print_height)}{endif} ; Move print head up
G1 X0 Y200; home X axis
M84 ; disable motors

M900 K0 ; disable linear advance for future prints


Re: material going out of nozzle while heating up or on idle and first layer problem

Thank you everybody for explanation, I didn't know that anybody can modify it for own priorities and create own start up procedure, which is great (and makes sense now).
Also thanks everybody for sharing their start procedure, I'll definitely use some of it.
I'm sure that it will help other newbies in the future, maybe some short mention in guidebook could be also useful.

RE:

I know, it's been a while, but here is my complete start g-code for PLA. For PETG I replace 140 °C nozzle temp with 170 °C and tested it by removing clogged PETG on an old metal sheet without damaging or moving the sheet. For me this worked well, since there is a short time when the nozzle is lifted, in which filament can be removed, while also the whole procedure takes only a little longer than the standard procedure by Prusa. I also kept bobstro's 'two blob' procedure to remove filament which has been accumulating during bed leveling.

M862.3 P "[printer_model]" ; printer model check bester STARTCODE
M862.1 P[nozzle_diameter] ; nozzle diameter check
M115 U3.9.2 ; tell printer latest fw version
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G92 E0.0
M221 S{if layer_height<0.075}100{else}95{endif}

; Don't change E values below. Excessive value can damage the printer.
{if print_settings_id=~/.*(DETAIL @MK3|QUALITY @MK3).*/}M907 E430 ; set extruder motor current{endif}
{if print_settings_id=~/.*(SPEED @MK3|DRAFT @MK3).*/}M907 E538 ; set extruder motor current{endif}

edited: I pasted the wrong gcode. Now it's the right one.