PLA curling at the nozzle

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Re: PLA curling at the nozzle

Post by philipy » Wed Oct 06, 2021 10:20 am

Two things come to mind as possibilities:
One is that you inadvertantly altered the Z height. I don't know how easy that would be on your machine.
The other is that you have got a bit of a nozzle blockage. I know Steve said to fit a new one in that case, but I've never found that necessary. I've had a few blockages after switching fillament types, which I cured by heating the head a little above the normal temperature for the higher melting point of the two. Then carefully pushing a length of fine phosphor bronze wire up from the bottom and gently wiggling it around. Then extrude a short length of filament to clear it and let it cool dow to normal temps.
Of course after that you then need to reset the Z and the levelling. :roll:
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Re: PLA curling at the nozzle

Post by -steves- » Wed Oct 06, 2021 11:57 am

philipy wrote: Wed Oct 06, 2021 10:20 am Two things come to mind as possibilities:
One is that you inadvertantly altered the Z height. I don't know how easy that would be on your machine.
The other is that you have got a bit of a nozzle blockage. I know Steve said to fit a new one in that case, but I've never found that necessary. I've had a few blockages after switching fillament types, which I cured by heating the head a little above the normal temperature for the higher melting point of the two. Then carefully pushing a length of fine phosphor bronze wire up from the bottom and gently wiggling it around. Then extrude a short length of filament to clear it and let it cool dow to normal temps.
Of course after that you then need to reset the Z and the levelling. :roll:
As Philip said, you can "sometimes" clean them, but I have had nozzles that while they appear to have been cleared and extrude correctly, within 10 - 15 mins of restarting printing they clog again, this is where I have found there is a tiny solid bit or "plastic fluff" or filament that somehow never clears, no matter what you try. For this reason and the price of a nozzle I just bin them and fit a new one. The first time I found this, it took me 2 days to find the problem as "I knew" the nozzle had been thoroughly cleaned and was extruding properly for as much filament as I wanted to extrude. Also cut off the PLA before the extruder and bin all of that too as after a blockage the PLA inside the tube can cause another blockage when it gets to the nozzle, no idea why but it can and does.

I run both my printers 24 x 7, one I never switch off unless essential as it saves the settings to the SD card and not on board, which is crap as I rotate about 10 cards through both printers, so it saves to one card and by the time I have to switch it off I never know which card to put in to get the settings back, so I have to reset the z height again. PITA! :oops:

Let us know how you get on, once printing you will be a happy puppy.

P.S. Are you saving the Z height settings and restoring them, then double checking they are still the same before printing?
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Re: PLA curling at the nozzle

Post by GAP » Wed Oct 06, 2021 9:17 pm

The Z height is set by moving the nozzle till it just touches the plate then adjust a microswitch till a click is heard.
When the switch operates the Z nozzle is supposed to be just above the plate.
There is a zero offset setting but apart from some experimenting it defaults to and that is where I leave it.
I am wondering is the coating on the glass plate has lost its adhesion properties after I cleaned it with isopropyl.
Graeme
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Re: PLA curling at the nozzle

Post by -steves- » Thu Oct 07, 2021 7:38 am

GAP wrote: Wed Oct 06, 2021 9:17 pm The Z height is set by moving the nozzle till it just touches the plate then adjust a microswitch till a click is heard.
When the switch operates the Z nozzle is supposed to be just above the plate.
There is a zero offset setting but apart from some experimenting it defaults to and that is where I leave it.
I am wondering is the coating on the glass plate has lost its adhesion properties after I cleaned it with isopropyl.
Is this the video you used to set the bed? https://www.youtube.com/watch?v=4JSa_r8xgX8
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Re: PLA curling at the nozzle

Post by GAP » Thu Oct 07, 2021 9:56 am

-steves- wrote: Thu Oct 07, 2021 7:38 am
GAP wrote: Wed Oct 06, 2021 9:17 pm The Z height is set by moving the nozzle till it just touches the plate then adjust a microswitch till a click is heard.
When the switch operates the Z nozzle is supposed to be just above the plate.
There is a zero offset setting but apart from some experimenting it defaults to and that is where I leave it.
I am wondering is the coating on the glass plate has lost its adhesion properties after I cleaned it with isopropyl.
Is this the video you used to set the bed? https://www.youtube.com/watch?v=4JSa_r8xgX8
It was one that I looked at.
Graeme
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Re: PLA curling at the nozzle

Post by GAP » Thu Oct 07, 2021 10:13 am

So starting from the beginning I adjusted the Z axis end stop and then levelled the bed following the user manual.
I then tried to print the bogie side file and got a mess around the nozzle.
Next I took the fan cover off the extruder end and cleaned the nozzle both inside (by pushing the needle supplied in and out of the hole after removing the filament) and the outside.
Another attempt to print ended up with another mess at the nozzle.
Cleaned the plastic away from the nozzle again and after the 6th attempt; success I got a good print.
I immediately tried to print the same file again straight after the first one finished (no change to any settings) about 1-2 minutes afterward and ended up with a conglomerated mess around the nozzle.
Cleaned all visible plastic from the nozzle and let the filament ooze through while the printer was getting ready to print after another 4 attempts all of which ended up as a mess when the print started, even though I cleaned the nozzle outside between attempts, I finally got another successful print albeit with some stray filament between open spaces around the print at the lower level.
These prints take about an hour each and the rate I am going I should have the 12 bogie sides and 6 bogie centres printed by Christmas 2023.
Graeme
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Re: PLA curling at the nozzle

Post by ge_rik » Thu Oct 07, 2021 12:28 pm

Can you take a few photos, Graeme? Would be good to see what the 'mess' looks like and maybe a photo of the printhead just as it starts printing.

It does sound to me like adhesion problems. Have you tried hairspray or Pritt?

Personally, I've never played around with the Z offset. After adjusting the Z microswitch, I just use the bed adjustment screws to get the optimum level.

Sometimes, I'll adjust the screws on the fly while the first layer is printing. I use a narrow brim (just five strips wide) rather than a raft. I've never had much success with rafts. Using a brim gives me a chance to make adjustments to the bed levelling screws while it's being printed. It's quite easy to see if the strip being printed is too squished, too proud or even not sticking.

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Re: PLA curling at the nozzle

Post by GAP » Thu Oct 07, 2021 10:06 pm

ge_rik wrote: Thu Oct 07, 2021 12:28 pm Can you take a few photos, Graeme? Would be good to see what the 'mess' looks like and maybe a photo of the printhead just as it starts printing.

It does sound to me like adhesion problems. Have you tried hairspray or Pritt?

Personally, I've never played around with the Z offset. After adjusting the Z microswitch, I just use the bed adjustment screws to get the optimum level.

Sometimes, I'll adjust the screws on the fly while the first layer is printing. I use a narrow brim (just five strips wide) rather than a raft. I've never had much success with rafts. Using a brim gives me a chance to make adjustments to the bed levelling screws while it's being printed. It's quite easy to see if the strip being printed is too squished, too proud or even not sticking.

Rik
No pictures unfortunately.
The mess is just a ball of filament stuck to the nozzle or some the first few passes of the brim and a ball of filament stuck to the nozzle.
All the successful have a brim that prints perfectly if it gets passed the first few passes.
I have noticed that sometimes the brim prints for about 10 passes then one side will curl up and catch on the nozzle.

I played with the Z offset early in the piece but have not touched it since.
Graeme
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Re: PLA curling at the nozzle

Post by philipy » Fri Oct 08, 2021 5:32 am

GAP wrote: Thu Oct 07, 2021 10:06 pm
All the successful have a brim that prints perfectly if it gets passed the first few passes.
I have noticed that sometimes the brim prints for about 10 passes then one side will curl up and catch on the nozzle.
I've had what sounds similar, occasionally.
It still sounds to me most like a combination of temperature (either/or bed and extrusion) , levelling and height.

In the instances where the first few passes are ok and then it lifts, what does the laid down filament look like? Is it noticeabley flattened on top, or is it rounded on top? Slightly flattened suggests that it is being pressed on to the bed, which is good for adhesion.
However if it is rounded and then eventually lifts, it suggests that the bed is still not completely level, despite your best efforts.

Writing that has jogged my memory and I've just remembered that I did once have a problem a bit like this with the bed itself. The flexible plastic surface sheet ( by 3-M I think) was getting a bit old but still seemed to have an acceptable surface, yet prints were failing. Eventually I realised that the glue holding the plastic sheet to the aluminium bed was not holding properly and that as it warmed up, very thin air bubbles underneath were expanding and pushing up, causing a small distortion in the flatness of the surface. The result being that, since levelling and height adjustments are carried out cold, everything seemed fine, but when warmed up there were almost imperceptable high spots which caused smearing, and gaps and lifting filament. I cured it by replacing the top sheet and everything went back to printing properly.

Not saying this is your problem, but may be worth looking at. My bubbles were almost impossible to see but could be felt by lightly running finger tips across the surface - be careful of the temperature though!
Philip

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Re: PLA curling at the nozzle

Post by GAP » Fri Oct 08, 2021 9:10 am

My bed is a glass plate covered with a coating of unknown material (feels rubbery) which consists of a large number of dots.
Seeing as its is less than 1 month old I have to surmise that it is still OK.
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Re: PLA curling at the nozzle

Post by ge_rik » Fri Oct 08, 2021 9:22 am

GAP wrote: Fri Oct 08, 2021 9:10 am My bed is a glass plate covered with a coating of unknown material (feels rubbery) which consists of a large number of dots.
Seeing as its is less than 1 month old I have to surmise that it is still OK.
My Eryone printer has the same sort of bed. After a few months, it lost its tackiness so I turned it over and now use the plain glass surface and Pritt.

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Re: PLA curling at the nozzle

Post by philipy » Fri Oct 08, 2021 11:51 am

GAP wrote: Fri Oct 08, 2021 9:10 am My bed is a glass plate covered with a coating of unknown material (feels rubbery) which consists of a large number of dots.
Seeing as its is less than 1 month old I have to surmise that it is still OK.
My problem wasn't with the covering itself, but the adhesive holding to the plate was ( I believe) failing, so that small areas weren't actually held down flat any longer. Areas of failing adhesive on a relatively large surface is fact of life but wouldn't normally be either noticeable or critical in most applications.
As I said, it may be irrelevant, but can't hurt to have look.
Philip

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Re: PLA curling at the nozzle

Post by -steves- » Fri Oct 08, 2021 7:01 pm

The Ender Glass plate is great, I swear by them and have had literally thousands of prints off them.

I would strongly suggest using an adhesion base of some description, I get intermittent results without it.

We could ideally do with a short video of the printer just starting from it's first move, before it lays down it's test line and then close up's of the test line being laid down and up to part way through the first layer. Please :D

If we see that, I am sure we can help much more :thumbup:
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Re: PLA curling at the nozzle

Post by GAP » Fri Oct 15, 2021 12:20 am

As requested a few pictures of the nozzle with the PLA build up.
This is after about 5 passes after the start of the print. there was nothing on the plate except for one pass down the side.
Out of over 20 attempts I have managed to print 3 items successfully so lack repeatability is a major issue here.
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P1060512.JPG
P1060512.JPG (56.97 KiB) Viewed 3585 times
This is another attempt it started out as a brim then curled up and tangled the nozzle
P1060513.JPG
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P1060514.JPG
P1060514.JPG (92.76 KiB) Viewed 3585 times
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Re: PLA curling at the nozzle

Post by philipy » Fri Oct 15, 2021 6:14 am

Looking at the split on the LH side of the leg of the T on the last picture made me wonder about the print speed you are using? If it is too fast, particularly on the first layer, it may not have time to 'stick' either to the bed or itself?
My software suggests a default speed of 50mm/sec but I find 60mm/sec seems to work well.
Philip

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Re: PLA curling at the nozzle

Post by ge_rik » Fri Oct 15, 2021 8:26 am

Are you sure the printhead is only a sheet of paper's width from the bed? I got hit and miss first layer problems like yours when I first set up my cheapo printer. Eventually I found the bed was distorted and so no matter how hard I tried to level it, there was always one corner which was either too close or too far from the head. Adding a glass bed helped, but I still get occasional problems with first layer adhesion.

Philip and I both make fine adjustments sometimes to the levelling screws while the head is making its first few passes of the brim. Rubbing your finger lightly from side to side over the deposited filament soon shows if it is sticking to the bed. If it isn't, loosen off the screw on the nearest corner.

Some people suggest the first layer should be slightly squished on the bed - ie closer than a paper' s width. Better a bit too close than a bit too far.

The All3DP website suggests these as the ideal settings for the Ender 3

Printing temperature: 200 °C
Bed temperature: 60 °C
Speed: 50 mm/s ( though lower down it suggests 60mm/s)
Layer height: 0.12 mm
Retraction: 6 mm @ 25 mm/s
Infill: 20%
Initial layer speed: 20 mm/s
Initial fan speed: 0%

As the article says, try starting with these settings and then tweaking one at a time to see what seems to be making the difference.
https://all3dp.com/2/ender-3-cura-setti ... a-profile/

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Re: PLA curling at the nozzle

Post by GAP » Fri Oct 15, 2021 12:29 pm

What a difference a day makes.
I changed 2 things at the same time (against my technician logical fault finding training) and got 3 successful prints one after the other.
1. I redid the bed levelling again but this time I pushed the paper under the nozzle after auto homing and used that feeling as my guide for the 4 corners of the bed when levelling again.
2. I changed the PLA from the "flash forge" brand to the "creality" brand and the first item (bogie centre) print went well, after that was finished and not changing anything I successfully printed 2 other items (bogie side) and again success.

The next thing I did was import the bogie centre and 2 bogie sides files into tinkercad and converted them into .stl files, followed by slicing them to get a G Code file.
Into the printer the new file went and it started to print well, about 50%, then all of a sudden the printer had a hissy fit and just randomly printed layers all over the place.
The only thing that I can put this hissy fit down to, is the fact the filament got tangled around the Z axis drive screw and was tight as a guitar string when I found it.
I did pause the print and pull the misprinted filament away but that did not work and it just misprinted again.
I am guessing that as I pulled some of the filament way I now had a nozzle height to the print level issue.

Another attempt will be made tomorrow (its 9.30pm now).
Might re slice the .stl file before I start.
All in all I am making progress albeit with baby steps.
Graeme
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Re: PLA curling at the nozzle

Post by ge_rik » Fri Oct 15, 2021 5:28 pm

GAP wrote: Fri Oct 15, 2021 12:29 pm.
1. I redid the bed levelling again but this time I pushed the paper under the nozzle after auto homing and used that feeling as my guide for the 4 corners of the bed when levelling again.
Aha! That might be significant. You must always autohome before levelling otherwise the Z axis might not be at zero..... Also, it does sound as if the filament you've been using isn't the best.

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Re: PLA curling at the nozzle

Post by GAP » Sat Oct 16, 2021 7:45 am

Another attempt and another fail.
Re-checked the auto home and levelling and it was way out again.
A BL touch is now a serious consideration, after I change the springs because when levelling there does not seem to be any tension on the springs at all.
Graeme
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Re: PLA curling at the nozzle

Post by ge_rik » Sat Oct 16, 2021 7:54 am

GAP wrote: Sat Oct 16, 2021 7:45 am Another attempt and another fail.
Re-checked the auto home and levelling and it was way out again.
A BL touch is now a serious consideration, after I change the springs because when levelling there does not seem to be any tension on the springs at all.
It does sound as if your bed adjustment screws aren't tight enough meaning they undo themselves while printing. Earlier on, Steve suggested tightening the bed screws down as tight as possible to compress the springs fully, then slackening them off a few turns before setting the Z stop. It might be worth giving that a try.

Rik
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