PETG pulled to start of print  

RE: PETG pulled to start of print

various people offer staged heat up profiles, to address this issue, have a look at Chris Waekocki's Pretty PLA, Pretty PETG and Pretty ABS Profiles

https://github.com/eoprede/prusa_profiles/tree/master/MK3/Slic3r

Regards Joan

RE: PETG pulled to start of print

With mine i just select preheat setting for the filament type i.e. PETG and leave it to heat up fully then wait for the excess filament to expand out of the nozzel. Then i select the print file and as the extruder drives to the bed for mesh leveling it remove excess off the nozzel with the long nose pliers.  Any excess after that is usually pulled off as the purge line is printed. But also i have a 2 line width skirt with most prints to ensure any stringing or blobs are taken off in this.

RE: PETG pulled to start of print

Collin,

To chime in with a similar response as Joan.  There are many different start/up heat up profiles you can use that will eliminate this problem.  I also found that DAMP/MOIST filament adds to the dribble/bird turd problem.  Make sure your filament is DRY.  I just got a dehydrator to do that.

Here are some additional GCODE start and end profiles that can help.  Thanks to Bobstro:

http://projects.ttlexceeded.com/3dprinting_slic3r_gcode.html

NOTE: These go into Prusa Slicer in the START and END custom GCODE.  Once saved you have them working properly for all filament.

He also has a lot of other tips for using Prusa Slicer and the MK3.

Happy Printing,

Robin

RE: PETG pulled to start of print

The string from purge to part is something I see from time to time. Almost always from the nozzle not being clean from teh start.  Use a paper towel or cardboard (per bob) and wipe the nozzle during the preheating phase to make sure there isn't cling-on filament from the last print.

No amount of preheat will dislodge this stuff and somehow during purge it always seems to catch the purge line then string.

RE: PETG pulled to start of print

Put a wipe motion (move nozzle back over prime line without extruding, then rapidly forward past end of prime line) at the end of your start gcode. See line 46 (subject to change) in this example. That's eliminated almost all of the "prime line to part" problems with many filaments.

RE: PETG pulled to start of print

Thanks Bob.  You helped me get rid of those so well.  😉

Make sure you put the GCODE fragments into the START and END code as instructed by Bobs web page.  It works great.  I have been using Prusament PETG and eSun PETG with flawless results.

That is unless the spool gets tangled.

My top 4 pre-flight checks are:

1) Dry the filament WELL

2) Clean the extruder well.

3) Clean the PEI/PC plate thoroughly.

4) Use the custom START/END GCODE

Robin

RE: PETG pulled to start of print

So Bob - would your purge wipe method cure this?  The string isn't from the end of the purge, it's higher up - coming from the nozzle and where it was "tacking down" at the final heating spot (which, by the way, is 10 mm up).

RE: PETG pulled to start of print

Posted by: Tim

So Bob - would your purge wipe method cure this?  The string isn't from the end of the purge, it's higher up - coming from the nozzle and where it was "tacking down" at the final heating spot (which, by the way, is 10 mm up).

Bit of a 2 part answer. I can say that I don't see that problem with PLA, PETG, nGen, nylon (Bridge). Here's my current startup gcode for reference (subject to change).

The wiping action (lines 45-48) I use is at the end of the purge line, but prior to that I do PINDA warmup (line 19-24) at the rear edge of the bed and final nozzle warmup (lines 29-35) at the home position raised 3-5mm, so any such ooze should form above the home position. I push 2mm of filament with no movement (line 41) at the start of the purge line and that usually traps any of those sorts of leftovers.

I have eliminated any sort of prime-to-print stringing for the most part. I sometimes get a spiderweb strand, but nothing that can break loose and make a mess being dragged about.  So to answer your question: The wiping action won't prevent that, but other steps should help. If you identify that filament and your temps, I can do a quick test and post pics.

RE: PETG pulled to start of print

PLA2 @ 215/210/60 ...

Keep in mind it looks like two strands being laid down. One extrusion, one dregs from prior whatever.

The culprit is plastic that seems to collect on the nozzle during prior print and ooze. If I remember to wipe the nozzle, it usually doesn't happen.   I do warm up at 185, and no ooze there.  It's the last 185-215 step that will collect a bit of ooze with some filaments, I keep the nozzle 10 mm off the bed.  Interestingly, this photo happens to be from a brand new spool, too. Fresh out of plastic. But other spools and PETG do the same, so not moisture that I can tell. Humidistate goes LL at <20% RH ... and that's what is showing. 

I may revert to parking the nozzle on the bed for the final heat, ooze will be captured rather than drip.

Also, just occurred to me I may have knicked the nozzle last time I cleaned it before a cal... hastily used a scalpel and the filament was cold.

RE: PETG pulled to start of print

Thanks for all the replies. Going to try and implement bobs suggestion. Gcode is all alien to me so I will try and make this work.

Thanks!!

RE: PETG pulled to start of print

This is how I pasted it in. Didnt seem to work. Almost seems like it wiped empty before doing the wipe line. Im sure its something I screwed up.

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
G1 E-0.8 F2100; retract to avoid stringing
G1 X99.5 E0 F1000.0 ; -0.5mm wipe action to avoid string
G1 X110.0 E0 F1000.0 ; +10mm intro line @ 0.00
G1 E0.6 F1500; de-retract
G92 E0.0
M221 S{if layer_height<0.075}100{else}95{endif}

RE: PETG pulled to start of print

Posted by: collin.j

This is how I pasted it in. Didnt seem to work. Almost seems like it wiped empty before doing the wipe line. Im sure its something I screwed up.

Just to confirm: You are using PrusaSlicer, correct? Does it continue on with the print after drawing the prime line?

RE: PETG pulled to start of print

Posted by: bobstro

Posted by: collin.j

This is how I pasted it in. Didnt seem to work. Almost seems like it wiped empty before doing the wipe line. Im sure its something I screwed up.

Just to confirm: You are using PrusaSlicer, correct? Does it continue on with the print after drawing the prime line?

Yes, using prusaslicer 2.0. It seemed to draw a prime line a little earlier, then made the normal prime line. Went straight from there to the print. 

I cleaned the nozzle a few times while it was preheating and it only dragged a small amount (web). I feel that the drippage during warmup is what is getting dragged through the prime line to the start of the print.

RE: PETG pulled to start of print

Posted by: Tim

[...]   I do warm up at 185, and no ooze there.  It's the last 185-215 step that will collect a bit of ooze with some filaments, I keep the nozzle 10 mm off the bed. 

The biggest difference I see is that you're using 185C for your no-ooze temp and I'm using 160C. I did have a bit of ooze early on at 170C, so scaled back. Perhaps you're right at the border of ooze and just spend more time above it during your warmup? There might be a bit of thermal inertia causing my "colder" filament to not fully warm up before the prime line starts. 

If you look further down my page, you'll see that I do a short 2mm retraction in my end gcode that might be helping, although I abort plenty of prints.

[...] Also, just occurred to me I may have knicked the nozzle last time I cleaned it before a cal... hastily used a scalpel and the filament was cold.

That would make sense. Disrupting the surface tension perhaps. I'm having good luck lately using a strip of cardboard for cleaning at temps. I figure it will avoid abrading, not damage coated nozzles and do a bit of stroping of the tip. Of course, it only helps if I remember to do it 1st!

RE: PETG pulled to start of print

Posted by: collin.j

Yes, using prusaslicer 2.0. It seemed to draw a prime line a little earlier, then made the normal prime line. Went straight from there to the print. 

Are you using Octoprint by any chance? And if so, are you using the Octolapse plugin? I recall getting a double prime-line when I enabled it. It would start at bed center and extrude the line left, then repeat with my line going left to right. Turned out it was a setting in Octoprint I had to clean up.

I cleaned the nozzle a few times while it was preheating and it only dragged a small amount (web). I feel that the drippage during warmup is what is getting dragged through the prime line to the start of the print.

I hover the nozzle above the bed at home position during final warmup, so if it oozes, it'll drop onto that position. When I hit printing temp, I lower the nozzle in place and extrude 2mm to create a sticky "blort" of filament to catch any remaining ooze, then print the rest of the prime line. I'm not seeing that done in the example you posted.

RE: PETG pulled to start of print

Posted by: bobstro

Posted by: collin.j

Yes, using prusaslicer 2.0. It seemed to draw a prime line a little earlier, then made the normal prime line. Went straight from there to the print. 

Are you using Octoprint by any chance? And if so, are you using the Octolapse plugin? I recall getting a double prime-line when I enabled it. It would start at bed center and extrude the line left, then repeat with my line going left to right. Turned out it was a setting in Octoprint I had to clean up.

I cleaned the nozzle a few times while it was preheating and it only dragged a small amount (web). I feel that the drippage during warmup is what is getting dragged through the prime line to the start of the print.

I hover the nozzle above the bed at home position during final warmup, so if it oozes, it'll drop onto that position. When I hit printing temp, I lower the nozzle in place and extrude 2mm to create a sticky "blort" of filament to catch any remaining ooze, then print the rest of the prime line. I'm not seeing that done in the example you posted.

No octoprint. 

Probably not seeing it because i simply copied and pasted from the example to try and retract, and drag another line. I have no clue what Im doing with gcode. Slowly figuring it out.

RE: PETG pulled to start of print

[...] Probably not seeing it because i simply copied and pasted from the example to try and retract, and drag another line. I have no clue what Im doing with gcode. Slowly figuring it out.

I've documented the major pieces. Take a look at each line, then read up on the corresponding gcode commands in the Marlin reference. Gcode is pretty clunky, but there's no real "programming" involved. Lots of individual commands, but you get familiar with the common ones quickly.

RE: PETG pulled to start of print

Learning this gcode. Dont understand what the F numbers are .

Example G1 X60.0 E9.0 F1000.0; intro line.

I understand G1 is linear movement. Move extruder to x 60mm while extracting 9mm but whats the F1000.0???

Thanks

RE: PETG pulled to start of print

Feed Rate in mm/min so max speed of 1000 mm/min for the move or 16.6 mm/sec