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First layer woes


stejan

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Posted · First layer woes

I am having problems with my first layer. It starts off smooth but has it progresses it gets quite lumpy has can be seen in the attached picture. I have researched this myself and i think i have ruled out all the common causes - 

 

1) Nozzle too close to the bed-. I dont think so. I have levelled the bed several times by hand to get it has level has possible. Then run the ABL routine to find the correct z  offset. On my machine it seems to be -1.11. I have tried various offsets between -0.95 and -1.18. It doesnt seem to make any difference, the layer starts off smooth and then gets lumpier has it goes. Anything higher then -1.11 causes issues with adhesion.

 

2) Incorrect extruder calibration-. Again, i have ruled this out. i have checked and its actually under extruding slightly. Running 100mm through actually resulted in 96mm being used. I have left it set has this has if i alter this its probably going to make the lumps even worse. 

 

3) Temperature- . I have tried various nozzle temps between 195 and 215 degrees and bed between 60 and 75 degrees. 

 

Has the layers go on it smooths itself out, when upto about layer 4 or 5 the issue seems to correct itself.

I am using Eryone PLA which i find to be very good apart from this first layer issue, especially with their matte black. Can different brands of PLA cause issues like this has Eryone is the only brand i have used up till now. I dont want to go and try a different make if it doesnt fix the issue. 

Any suggestions would be gratefully received.

IMG_20220529_145113152.jpg

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    Posted · First layer woes

    I just saw this.  What printer is that (looks like a Creality layer cooling fan)?

    If it is a Creality printer and you still have the stock plastic extruder - have you checked the extruder arm for cracks?  They usually appear on the underside of the arm around the pivot hole.

    It looks like the problem happens suddenly like it's fine and then it's a mess.  If that's true then it appears to be a mechanical issue rather than the filament.  

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    Posted · First layer woes
    5 hours ago, GregValiant said:

    I just saw this.  What printer is that (looks like a Creality layer cooling fan)?

    If it is a Creality printer and you still have the stock plastic extruder - have you checked the extruder arm for cracks?  They usually appear on the underside of the arm around the pivot hole.

    It looks like the problem happens suddenly like it's fine and then it's a mess.  If that's true then it appears to be a mechanical issue rather than the filament.  

     

    Its an Ender 5 Pro with the all metal extruder  which i have checked and is in good condition. It always happens on the first layer, by the time it gets to layer 3- 5 its silky smooth. One thing i have tried today is to lower the temperature to 190 degrees and its helped a bit but not cured it completely. Dont really want to go lower then that because the Eryone filament recommends 190 - 220 degrees.

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    Posted · First layer woes

    have you checked if the initial layer temp is set the same? if you say it only happens at the first layer, 

    In Cura the first layer temp can be different 

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    Posted · First layer woes
    On 6/22/2022 at 2:19 PM, dsp said:

    have you checked if the initial layer temp is set the same? if you say it only happens at the first layer, 

    In Cura the first layer temp can be different 

    Yes, 65 degrees the same, i have tried temps ranging from 50 - 70 and still the same.

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    Posted · First layer woes

    I'm just thinking out loud here.

    I believe the bed on your printer is controlled by a thermostat.  If the bed cools a bit, the thermostat turns in on.  When it gets up to temp the thermostat turns it off.  So it cycles from fully on, to fully off and all that current for the bed heater goes through the mainboard.  It's a "Bang-Bang" setup.

    The hot end is PWM controlled.  It's running constantly with a fairly constant current draw when all of a sudden the bed goes on and sucks current away from the hot end causing the hot end go cool until the mainboard can balance things again, and then the bed turns off and the problem reverses itself.

    That's pretty big build surface.  Maybe it's just taking a while before the bed comes to a stable state with a uniform temperature across the whole surface.  If that is the case then it's possible that just adding a pause of 3 or 4 minutes minutes after the heating commands (in your StartUp Gcode) would allow the bed to settle down.  It would still be a "bang-bang" cycle but the high (and long) initial high current draws might be over with when the print starts.

    The Marlin "Dwell" command is G4 so "G4 S300" would be a 5 minute pause.  If you try that, remember that the hot end will want to ooze during that period so the nozzle needs to be at the Auto-Home location and will the Z at about 10 so the nozzle is off the bed, or you could put off heating the hot end until the bed was stable.

    I added one of these 24v MOSFET Power Supply to my Ender 3 Pro.  It moves the bed current off the mainboard and uses the bed heater output wires from the mainboard as it's control.

     

     

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    Posted · First layer woes
    1 hour ago, GregValiant said:

    I'm just thinking out loud here.

    I believe the bed on your printer is controlled by a thermostat.  If the bed cools a bit, the thermostat turns in on.  When it gets up to temp the thermostat turns it off.  So it cycles from fully on, to fully off and all that current for the bed heater goes through the mainboard.  It's a "Bang-Bang" setup.

    The hot end is PWM controlled.  It's running constantly with a fairly constant current draw when all of a sudden the bed goes on and sucks current away from the hot end causing the hot end go cool until the mainboard can balance things again, and then the bed turns off and the problem reverses itself.

    That's pretty big build surface.  Maybe it's just taking a while before the bed comes to a stable state with a uniform temperature across the whole surface.  If that is the case then it's possible that just adding a pause of 3 or 4 minutes minutes after the heating commands (in your StartUp Gcode) would allow the bed to settle down.  It would still be a "bang-bang" cycle but the high (and long) initial high current draws might be over with when the print starts.

    The Marlin "Dwell" command is G4 so "G4 S300" would be a 5 minute pause.  If you try that, remember that the hot end will want to ooze during that period so the nozzle needs to be at the Auto-Home location and will the Z at about 10 so the nozzle is off the bed, or you could put off heating the hot end until the bed was stable.

    I added one of these 24v MOSFET Power Supply to my Ender 3 Pro.  It moves the bed current off the mainboard and uses the bed heater output wires from the mainboard as it's control.

     

     

     

    The temperature seems pretty consistent but i will certainly look into the possibility. I normally leave the bed temp to normalise for around 10 minutes before i start a print. 

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    Posted · First layer woes

    10 minutes is plenty so that G4 experiment probably won't change anything.  That problem sure looks like someone threw the "screw up the print now" switch.  It happens all-of-a-sudden so I'm still considering that it's something on the printer end rather than something going on with the gcode.

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    Posted · First layer woes

    Still cant work out whats causing this. Here is the start of a print i did earlier. Has you can see it starts off beautifully smooth in the top left corner, but has it goes on it gets rougher, lumpy and stringy. By the time it gets to layer three or four it smooths itself out and is back to normal. Someone must have an answer, its probably something simple but i cant seem to nail it. Help !!

     

     

    IMG_20220705_141335987.jpg

    IMG_20220705_141341202.jpg

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    Posted · First layer woes

    Post that Gcode file here.  I've got some scrap PLA that I can throw at it.  If it does it on my printer then it's in the gcode.  If it doesn't then it's in your printer.  I think at this point narrowing it down would be helpful.

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    Posted · First layer woes

    Hello mate

    Thats very good of you. I cant see how it could be the code but its worth a try. Maybe some setting i need to alter. There are that many tweaks in Cura and i dont know what a lot of them even do. Anyway, here is the code - 

    Trim box top SKIN.gcode

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    Posted · First layer woes

    I printed a bit of that gocde.  It was fine.  

    Looking back at your images, what the heck is all that black stuff coming out of your nozzle?  If some of that is getting hung up in the nozzle orifice then you will get inconsistent extrusion.

    Your hot end may just need a good cleaning.  Have you checked the bowden tube end that is within the hot end?  If it is breaking down then that may be the source of the black debris.  Enders are notorious for developing partial blockages between the back of the nozzle and the end of the bowden tube.

    Pull out the nozzle and clean out the hot end with a "just right" diameter coat hanger or other appropriate wire.  Trim off 5 or 6mm of the bowden making a nice square cut, and put the hot end back together.  The hot end must be heated up to 180 or so for all of that.

     

    Your print temp at 200 is fine.  Is your printer equipped with the stock hot end?  If not then did you do a PID auto-tune on the new one?

     

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    Posted · First layer woes
    4 hours ago, GregValiant said:

    I printed a bit of that gocde.  It was fine.  

    Looking back at your images, what the heck is all that black stuff coming out of your nozzle?  If some of that is getting hung up in the nozzle orifice then you will get inconsistent extrusion.

    Your hot end may just need a good cleaning.  Have you checked the bowden tube end that is within the hot end?  If it is breaking down then that may be the source of the black debris.  Enders are notorious for developing partial blockages between the back of the nozzle and the end of the bowden tube.

    Pull out the nozzle and clean out the hot end with a "just right" diameter coat hanger or other appropriate wire.  Trim off 5 or 6mm of the bowden making a nice square cut, and put the hot end back together.  The hot end must be heated up to 180 or so for all of that.

     

    Your print temp at 200 is fine.  Is your printer equipped with the stock hot end?  If not then did you do a PID auto-tune on the new one?

     

    Thanks for running the code for me. That black crap is actually how the plastic extrudes after a certain point. Its very lumpy and stringy. The thing is it clears itself after a couple of layers, would it do that if it was a partial clog? I changed the bowden tube a couple of months ago and the nozzle last week. I will strip it back down and have a look at it though. 

     

    Its still possible that it is a z offset problem, i raised the nozzle by 0.02mm earlier and it was printing better, but still not right. The trouble is i cant find a suitable balance. With it set where it is now the plastic doesnt stick to the bed half the time, but if i lower it it will probably lump up more again. Im getting close to throwing it out of the window 😬

    I use the stock hotend, would it benefit from upgrading the hotend? If so do you have any recommendations?

    Thanks

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    Posted · First layer woes

    My printer is an Ender 3 Pro about 2 1/2 years old now.  I started out with what is probably the same hot end that you have.  I passed a lot of PETG through it in the first couple of months and it developed a problem with constant partial blockages that caused a LOT of under-extrusion.  After replacing everything except the hot end I bought a clone of the stock Creality hot end.  That lead to a new saying..."When you clone a POS you should not be surprised that the clone is also a POS."  I finally went with a Micro-Swiss all-metal hot end that bolted right up.  It was the best change I've made in the printer.  About every 40 hours of print time I still take it apart, trim back the bowden tube 5 or 6 mm and clean out the heat exchanger and hot block, but it has been 100% better than the stock one.

    BTW that black stuff can be a function of the material spending too much time in the Hot End.  You might want to consider setting "Number of Slower Layers" to 0 and make your Initial Layer Speed the same as your print speed.

    A trick you might try for better first layer adhesion is to set the Initial Layer Flow to 105% or even 110%.  You have to get the squish for the plastic to stick to the build surface.  I always use hair spray for PETG but I only use it for PLA on certain models that have a small footprint on the bed.

     

    So far in the International Printer Toss competition the leader of the "Horizontal Heave" class is a fella who had an Xvico.  In the "Defenestration Division" is an Ultimaker S5.  You will have to go a ways to beat those guys.  They were really irate.

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    Posted · First layer woes
    54 minutes ago, GregValiant said:

    My printer is an Ender 3 Pro about 2 1/2 years old now.  I started out with what is probably the same hot end that you have.  I passed a lot of PETG through it in the first couple of months and it developed a problem with constant partial blockages that caused a LOT of under-extrusion.  After replacing everything except the hot end I bought a clone of the stock Creality hot end.  That lead to a new saying..."When you clone a POS you should not be surprised that the clone is also a POS."  I finally went with a Micro-Swiss all-metal hot end that bolted right up.  It was the best change I've made in the printer.  About every 40 hours of print time I still take it apart, trim back the bowden tube 5 or 6 mm and clean out the heat exchanger and hot block, but it has been 100% better than the stock one.

    BTW that black stuff can be a function of the material spending too much time in the Hot End.  You might want to consider setting "Number of Slower Layers" to 0 and make your Initial Layer Speed the same as your print speed.

    A trick you might try for better first layer adhesion is to set the Initial Layer Flow to 105% or even 110%.  You have to get the squish for the plastic to stick to the build surface.  I always use hair spray for PETG but I only use it for PLA on certain models that have a small footprint on the bed.

     

    So far in the International Printer Toss competition the leader of the "Horizontal Heave" class is a fella who had an Xvico.  In the "Defenestration Division" is an Ultimaker S5.  You will have to go a ways to beat those guys.  They were really irate.

     

    Thanks for all your help and advice. I will clean it out, and try messing about with the initial layer speed and flow etc.

    I will let you know how i get on in a few days 👍

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    Posted · First layer woes

    Be aware that most "all metal" hot ends won't print PLA.  Or not well.  Some will.  Most won't.  Molten PLA sticks to all metals in a bad way and if this happens up where the PLA is cooler than 100C, say around 60C, and if temperatures are going well above and below (due to retractions or just changes in print speed) then the filament can stick to the side of the upper portion of the hot end and just get stuck there.

     

    PLA is pretty much the only material with this issue so if you are printing nGen, CPE, PETG, ABS, PP, or Nylon then it should be fine.

     

    Hot ends with a very short heat break don't have this problem because although the PLA can stick right at the heat break, the length of the heat break is short enough that the feeder can usually overcome the sticking force.

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    Posted · First layer woes

    The main difference that I can see is that the narrow neck of the heat break keeps the bowden tube 6 or 8mm above the end of the nozzle.  It's a titanium heat break so it has a slightly less heat conduction coefficient than a stainless steel break.

    At any rate I haven't had the problem recurring (partial clog in the hot end) since I put it in 1 1/2 years ago.

    I'm careful when swapping nozzles but the stock Creality heat block was made of some really soft alloy and the nozzle threads stripped in a heart beat.

    I'd say the main problem I have with the hot end now is that the constant rotation of the bowden tube in the lock fitting allows the teeth in the fitting to work their way into the tube.  This makes for in and out movement of the tube within the fitting (1 to 1.5mm) and affects the retractions.  Nothing to do then but to trim it back so the teeth bite a new area.

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    Posted · First layer woes

    @GregValiant - you didn't mention if you have ever printed PLA with this all metal hot end from micro-swiss.  And was it like 2 hours of PLA prints or > 20 hours of prints?

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    Posted · First layer woes

    Hi @gr5.  I've pushed a lot of PLA through it.  The longest prints were back-to-back 15 hour prints for the "cafe" tail section of my gas bike.

    Other than the narrow-necked heat break the hot end looks a lot like the stock Creality hot end.  It was a bolt-in replacement so is it truly an "all-metal" style hot end, or is it just a hot end made from "all metal" parts?  It works for me.

    PS:  There are 55 printed parts on the bike.  The only parts that are not PLA are the velocity stack mount and the internal air filter retainer which as PETG as they see gasoline.

    162246566_ABike1.thumb.JPG.d6cb25619a248436b04e544606d11d62.JPG

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    Posted · First layer woes
    On 7/7/2022 at 8:10 PM, gr5 said:

    Be aware that most "all metal" hot ends won't print PLA.  Or not well.  Some will.  Most won't.  Molten PLA sticks to all metals in a bad way and if this happens up where the PLA is cooler than 100C, say around 60C, and if temperatures are going well above and below (due to retractions or just changes in print speed) then the filament can stick to the side of the upper portion of the hot end and just get stuck there.

     

    PLA is pretty much the only material with this issue so if you are printing nGen, CPE, PETG, ABS, PP, or Nylon then it should be fine.

     

    Hot ends with a very short heat break don't have this problem because although the PLA can stick right at the heat break, the length of the heat break is short enough that the feeder can usually overcome the sticking force.

    Oh bollocks, i have just ordered the micro swiss hot end and i only print in PLA. Hope i havent made a mistake

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    Posted · First layer woes

    Well according to Greg, it sounds like it will work great.

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    Posted · First layer woes

    I have just installed the Micro Swiss hot end and started a print. So far so good has you can see from the picture. A line did lift slightly in the center has you can see, but i suppose its never going to be perfect.

     

    I didnt do a PID tune, has i haven't got a clue how to do it and even if its necessary has it wasnt mentioned on the micro swiss website. I did turn the temp up 5 degrees and lower the retraction from 6mm to 3.5mm has recommended on the Micro Swiss website and it seems to be going okay. The extruder did 'knock' once early on but i'm hoping it was a one off. I just hope it doesnt clog with the PLA after what some have said but i shall see. 

     

    I had a look in the other one when i took it off and there was a build up of black crap inside, and also the bowden tube looked black and charred, which is annoying has it was only changed a couple of months ago ! ✌️ 

     

     

    IMG_20220711_153436558.jpg

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    Posted (edited) · First layer woes

    "...but i suppose its never going to be perfect." 

    It should be closer to perfect than that.  It shouldn't break loose and pull into the center.

    Check that your "Wall Order" set to "Inside to Outside"?

     

    "I didn't do a PID tune" 

    If you changed the heater and/or the thermistor you need to do the PID tune.  You can't do it from Cura because you need to see the results.

    You can use either Pronterface or the little printing app (for Windows) I've attached.  Either way, send M503 and then check the M301 line for your current PID values.

    The Auto-Tune command would be "M303 S210 C8" where the S parameter is the target temperature and the C parameter is the number of times to repeat (6 or 8 work well).

    It takes a few minutes to run. 

     

    M503 results showing the current PID values in the M301 line.

    947913462_PIDM503.thumb.png.fa3d88436fc02c822ecc616fd59b4d1b.png

     

    M303 has finished:

    PID.thumb.png.abc5839a4b899d5a842141aabf0c9826.png

     

    I've never gotten the exact same results twice in a row but they seem to be "close enough".

    If you have the layer cooling fan on 100% while Auto-Tune runs you will get slightly different results dependent on how much the nozzle cools due to the fan blowing on it.

    After running the Auto-Tune you would need to send "M301 Pxx.xx Ix.xx Dxx.xx" to the printer followed by "M500" to save the new values in the printer.  You could then send M503 again to double check.

     

    The bowden tube is a consumable item.  You would usually just need to cut 5 or 6mm off the end that goes into the hot end.  One thing that will continue to happen is that the bowden tube rotates in the top fitting.  That causes the knife edges in the fitting to keep going deeper into the plastic tube which in turn allows some up-down movement during retraction and prime moves.  That "slop" will eat away at your retraction distance as more movement is required to take up the slack.  That's when I pull it and trim it back some more so the fitting bites into a new spot on the tube.  Eventually it gets too short and needs replacement.  Because the bowden no longer goes all the way to the nozzle the bottom end won't suffer from heat damage nearly as much.

     

    Greg's SD Print Tool.zip

    Edited by GregValiant
    Update Zip File
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    Posted · First layer woes

    I didn't change the heater cartridge or the thermistor, i just put the originals back in the new block. Does that mean i dont need to do a PID tune? Im only asking has the printer is enclosed out the back and i dont really want to hump it in to connect it to the PC if its not necessary. I dont have a laptop, im a PC gamer so just an enormous desktop.😃

     

    I have just finished a six hour print which went well so im hoping its now ok. Whilst im on can i pick your brain again. Can you see in the picture i posted where there is a small curl of filament inside the two holes? 

    This always seems to happen when the printer starts a new section, a little PLA always moves before it 'grabs' hold of the bed, normally its fine but occasionally it messes up when it goes back near it. Is there a setting(s) in Cura which can help with this problem?

    All the best 

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