Layers do not stick together?



  • Hi *,

    First of all I have to admit that I'm not yet very experienced in 3D printing. I love the concept of duet3d, I like the community. So I decided to change my Creatlity CR10s Pro v2 two month after he joined my household to a Duet2. 🙂 And he got a Bondtech extruder for various problems with the stock extruder, too.

    I work currently on a adapter to mount a Bondtech extruder to my ratrig V-Core. Today was the day to print the main part (6,5 hours) with the "final" parameters. The print went well, but the outcome was not very promising.

    The file developed a cleft (is that the right word? Sorry, English is not my mother language) while I was sub-ducting the support. I have to admit that I needed to apply some force to get some of the support out of it. But I can clearly see that the layers are not truly melted together. Well, some spots are melted together but the most not. The melted parts are easy identifiable because the black filaments is whiteish when I tear of a layer. The other look simply squeezed, like the first layer.

    I use PLA (Geetech) with 210°C and I reduced the Fan speed to 90% already. I used a layer height of 1,5mm and 6 wall lines.

    I may have a little bit of under extrusion, this is something I will work on this night.

    Is there anything else I need to look after?

    Cheers, Chriss



  • The common suspects are :
    Under extrusion
    Too low a temperature
    Too much cooling (therefore also resulting in #2 above)

    Of course there are many more.

    I would suggest upping temperature to 220 and cooling to 50% or less unless you have a specific reason to run the fan high. Also, be sure that you have calibrated your extruder (as you said you would)

    Good choice to replace the stock extruder!



  • @jens55

    220? Are you sure? My understanding is, so far, that I'm already at the upper limit with my 210. But I will give it a try.
    I have a Microswiss hotend around. I had some problem with that in the past. The all metal design is the suspect of some agglutination problems in the "past". Whatever past means here in my short 3D printer experience period. It may worth the time to test with that. The guys from Creality are a bit to creative with there nozzle thread design in my opinion.



  • It depends on the filament you use but I routinely use 215 to 220 for PLA. Also, just because your Duet reports 210, it doesn't mean you are actually at that temperature. Consider the temperature to be within 10C of the displayed value unless you have a way of confirming the actual temperature.
    I have a CR10 that has a Microswiss hot end installed and it's working just fine.
    No idea what 'agglutination' refers to. I also have no idea what you are referring to with 'nozzle thread design'.

    As far as upper limit is concerned, that's a bit of a 'how long is a string' type question. For example, if you were printing at a high volumetric rate, you might have to go well above the recommended temperature to get a good print. By the same token, if you were to print at a very low volumetric flow, you might want to reduce nozzle temperature.



  • @jens55 said in Layers do not stick together?:

    Also, just because your Duet reports 210, it doesn't mean you are actually at that temperature.

    Good point, I my internal filter system messed up my thoughts here. 😉

    I have a CR10 that has a Microswiss hot end installed and it's working just fine.

    With the stock metal housing (fan holder)? It seems to me that the fan is not well positioned for a Microswiss. It seems to me that only a tiny part of the hotend is covered by the fan.
    And some people in a CR10 group told me that the combination of a all metal hotend and a bowden extruder is not a very good combination at all.

    No idea what 'agglutination' refers to. I also have no idea what you are referring to with 'nozzle thread design'.

    I revere with "agglutination" to the problem that the inner, metal, part got to hot and the filament melted upwards, got a bigger diameter and got stuck. So the extruder became a saw because he was not able to move the filament any more.

    The thread in the nozzle is a non standard design, so I'm limited to the nozzles from Creality. I think that they use M6x1.5 where the rest of the world uses M6x1 or something like that. 😞 (Specials "greetings" to my friends in China!)

    As far as upper limit is concerned, that's a bit of a 'how long is a string' type question.

    Sure, less time to transport the same amount of energy into the material.

    Cheers, Chriss



  • @Chriss said in Layers do not stick together?:

    @jens55 said in Layers do not stick together?:

    With the stock metal housing (fan holder)? It seems to me that the fan is not well positioned for a Microswiss. It seems to me that only a tiny part of the hotend is covered by the fan.

    Yes, I am using the stock metal fan housing. Agreed it's not optimal but it works.
    My setup is a couple of years old so I don't know what differences there are with today's version. For one, I have only ever used bog standard tips.

    And some people in a CR10 group told me that the combination of a all metal hotend and a bowden extruder is not a very good combination at all.

    I have heard the same rumours ... it might be a bit tricky to get right (I think I have had some issues if I recall) but it will work just fine.

    I revere with "agglutination" to the problem that the inner, metal, part got to hot and the filament melted upwards, got a bigger diameter and got stuck. So the extruder became a saw because he was not able to move the filament any more.

    I forget what issues I had originally. I am pretty sure that getting too hot was one of them. Unfortunately I don't know what the answer was, I just know it works now.

    The thread in the nozzle is a non standard design, so I'm limited to the nozzles from Creality. I think that they use M6x1.5 where the rest of the world uses M6x1 or something like that. 😞 (Specials "greetings" to my friends in China!)

    See above re standard nozzles



  • Hi,

    What size nozzle are you using?

    Frederick



  • @jens55 said in Layers do not stick together?:

    @Chriss said in Layers do not stick together?:

    @jens55 said in Layers do not stick together?:

    Yes, I am using the stock metal fan housing. Agreed it's not optimal but it works.

    I saw same "better" designs came up at thingiverse for the CR10 with a bltouch. I will see if I find there a better solution.

    I forget what issues I had originally. I am pretty sure that getting too hot was one of them. Unfortunately I don't know what the answer was, I just know it works now.

    I bet that this is a standard problem with bowden extrudes. The high retraction distance transports the head up into the, supposed to be, cool part of the hotend.

    I printed a test cube with one wall line with a with of 0,4mm with my 0,4mm nozzle. My micrometer calliper told me that the wall is 0,4mm thick. 👍
    A second print with 130% resulted in a 0,495mm thick wall. I would have expected something differently but it is clear to me that my "extrusion factor" seems very good.

    But the first layer looks very much like under extrusion, but that can be caused by a slightly to low z-offset. I want to solve by "meting" problem first.

    The 220°C did not made it, I will play with the fan now and a bit more temperature.

    I have forgotten to mention that I measured the filament and it is 1.75mm. And yes, I know how to read my micrometer calliper. 😉

    @fcwilt 0,4mm

    Cheers, Chriss



  • @fcwilt, standard is 0.4 mm but I have 0.2 and 0.3 as well.



  • @jens55

    And I have forgotten to mention that I actually liked the 130%. I print the "floor" with one layer only, too. The floor is a thin closed plastic membrane when I have it at 130%. But the wall it to thick than.
    I do not know how I should describe the floor when it is at 100%, it is more a array of separate strings.

    The fan at 50% in the combination with 220°C improved the boundary between the layers.
    I bet that I will end up in a stringing hell at the end. But this is a problem for tomorrow. 😉

    Let's see how the print with 230°C will look like.

    (Bed temp: 60°C, first layer without cooling.)

    Cheers, Chriss



  • @Chriss said in Layers do not stick together?:

    I saw same "better" designs came up at thingiverse for the CR10 with a bltouch. I will see if I find there a better solution.

    I also use a BLTouch

    I forget what issues I had originally. I am pretty sure that getting too hot was one of them. Unfortunately I don't know what the answer was, I just know it works now.

    I bet that this is a standard problem with bowden extrudes. The high retraction distance transports the head up into the, supposed to be, cool part of the hotend.

    One thing that I just recall was retraction amount. A large amount of retraction always resulted in a clogged hot end. I don't recall the exact maximum but try below 2 mm of retraction.

    I printed a test cube with one wall line with a with of 0,4mm with my 0,4mm nozzle. My micrometer calliper told me that the wall is 0,4mm thick. 👍
    A second print with 130% resulted in a 0,495mm thick wall. I would have expected something differently but it is clear to me that my "extrusion factor" seems very good.

    Before you mess with the extrusion factor, you need to calibrate your extrusion distance. This is done by marking the filament 100 mm from your extruder (on the spool side), extruding 100 mm and looking where the mark is in relation to the extruder. You tweak the extruder step figure.
    There are differing opinions but I do my measurement while the nozzle is installed (other people remove the nozzle when they run the test)

    But the first layer looks very much like under extrusion, but that can be caused by a slightly to low z-offset. I want to solve by "meting" problem first.

    Yes, first layer issues are ironed out only after everything else is sorted.

    The 220°C did not made it, I will play with the fan now and a bit more temperature.

    If your fan happens to blow onto the nozzle or if you get reflection of cooling air off the model, the extra nozzle temperature will not be enough. Just leave it at 220 and reduce the cooling fan.



  • @Chriss said in Layers do not stick together?:

    @jens55

    And I have forgotten to mention that I actually liked the 130%. I print the "floor" with one layer only, too. The floor is a thin closed plastic membrane when I have it at 130%. But the wall it to thick than.

    If you use 130% for the first layer and you get a thin membrane then your nozzle is too high over the bed.
    Make sure you use the 130% only on the first layer (I am using Cura) rather than on everything else.

    I do not know how I should describe the floor when it is at 100%, it is more a array of separate strings.

    Yes, this is under extrusion but you can only tinker with any of these settings once you have the extruder calibrated! Don't try to set extrusion factor until you have things calibrated!

    I can't stress enough how important it is to calibrate the extruder first !!!

    Once the extruder is calibrated, you can tackle the extrusion factor for the main body of the print. That is different from the first layer! I would suggest that you set the extrusion factor for the first level the same as that for all subsequent layers and it should be close to 100%. I would then suggest you babystep the nozzle down, leaving the extrusion factor alone, until you get good adhesion and a nice even layer on the bed.

    The fan at 50% in the combination with 220°C improved the boundary between the layers.
    I bet that I will end up in a stringing hell at the end. But this is a problem for tomorrow. 😉

    Let's see how the print with 230°C will look like.

    (Bed temp: 60°C, first layer without cooling.)

    It is not likely to be stringy unless you have some other underlying issues.
    230 isn't necessarily too much but again, I would suggest reducing fan before upping the temperature.

    I would also suggest 70/75C for the bed.



  • @jens55 said in Layers do not stick together?:

    @Chriss said in Layers do not stick together?:

    @jens55

    If you use 130% for the first layer and you get a thin membrane then your nozzle is too high over the bed.

    Yes, that is what I learned some minutes ago, too. I measured with a paper some days ago. Today I found a far better method: https://forum.duet3d.com/topic/16714/z-offset-paper-alternative
    And guess what, that made it. The strings are gone and my floor is now close to 0,16mm while configured 0.14mm at cura. I'm getting closer. One or two further iterations and it will be "perfect". 😉

    Make sure you use the 130% only on the first layer (I am using Cura) rather than on everything else.

    Well, the 130% was for testing only, the goal should be to have a proper setup without any tweaks. I raised it up to 130% to see the effect and I wanted to learn how much affect I would see there. That should not be a permanent solution.

    I can't stress enough how important it is to calibrate the extruder first !!!

    Indeed, the extruder itself is calibrated. I did it some days ago when I implanted the bondtech extruder. Which is worth every penny!

    I would also suggest 70/75C for the bed.

    That is funny, you are always 10°C on top of my upper "limit". 😉 I will play with that when I'm done with my z-offset tuning.

    But I have to admit that all of that tweaks brought a lot of improvement! The layers stick far better together! So good that we switch to a hotend and z-offset discussion. 😄

    Cheers, Chriss



  • @Chriss said in Layers do not stick together?:

    The strings are gone and my floor is now close to 0,16mm while configured 0.14mm at cura. I'm getting closer. One or two further iterations and it will be "perfect". 😉

    I would suggest that you use 0.2 mm as the thinnest first layer. Even with that, you better have a dense bed mesh calibration done. Yes you can do thinner first layers but it causes too many issues unless you need the first layer to be thin for a reason. Generally, a thicker first layer covers many tiny issues.

    A lot of times I use 0.3 mm for the first layer. It's probably a 50/50 split for me between 0.2 mm and 0.3 mm.

    I would also suggest 70/75C for the bed.

    That is funny, you are always 10°C on top of my upper "limit". 😉 I will play with that when I'm done with my z-offset tuning.

    I print on clean glass without any adhesion enhancers and there is a fairly sharp range of temperature between 'too cold' with no sticking and 'sticks like a hot damn'



  • @jens55 said in Layers do not stick together?:

    I would suggest that you use 0.2 mm as the thinnest first layer.
    A lot of times I use 0.3 mm for the first layer. It's probably a 50/50 split for me between 0.2 mm and 0.3 mm.

    I guess that I use "usually" 0,05mm more than the other layers. I do not know the reason for that, I guess that I read that as the "rule of thumb" somewhere. Well, I found a nice explanation how to calibrate with the help of a empty cube, they recommended 0,15mm for the layers and 0,14 for the first. I simply followed there advice here for that calibration drill.

    Fun fact: I have now my 0,14mm as I told him to do so. Now I see my beloved Elephant's Foot. Let's see how it will be when I make the first thicker. Funny what you can do in a sleepless night. 😉

    I print on clean glass without any adhesion enhancers and there is a fairly sharp range of temperature between 'too cold' with no sticking and 'sticks like a hot damn'

    I think that this makes the difference here, I print at a PEI coated plate. PLA sticks on that so phenomenal, I would not change the temperature if it would not have a positive effect to the first layer.

    BTW:

    I forget what issues I had originally.

    I can remember what I had! The hotend is in total a bit shorter than the stock hotend. At lest from the mounting holes to the tip of the nozzle. That made my air funnel unusable and I was not able to find a very good replacement. The one I found needed a lot of massage with a file. I think that this is solvable but the problem with the blocked nozzle... well... It will it be worth the time to give it one more try at the end.

    Cheers, Chriss



  • @Chriss said in Layers do not stick together?:

    Fun fact: I have now my 0,14mm as I told him to do so. Now I see my beloved Elephant's Foot. Let's see how it will be when I make the first thicker. Funny what you can do in a sleepless night. 😉

    Drop first layer temp by 5 or 10 degrees until the elephant food is minimized.

    I think that this makes the difference here, I print at a PEI coated plate. PLA sticks on that so phenomenal, I would not change the temperature if it would not have a positive effect to the first layer.

    Ah yes, PEI sticks well ... I had too much trouble with PEI so I discontinued using it.



  • @jens55 said in Layers do not stick together?:

    Drop first layer temp by 5 or 10 degrees until the elephant food is minimized.

    I print the first layer with 220°C and the rest with 230°C. Seems very good now. I will perform some stringing tests now, let's see how bad that will be. 😉

    Ah yes, PEI sticks well ... I had too much trouble with PEI so I discontinued using it.

    Really? What kind of trouble did you had? It works for me very, very well. bloody expensive but works very nice.

    Thanks you very much! I had a lot of fun spending the night with your very nice and friendly input! 🙂 I owe you at least one beer. 😉 Your motivated me to go ahead with the calibration! Thanks!

    Cheers, Chriss



  • My PEI sheet came with a 3M glue sheet to stick to a glass plate. The glue let go at too low a temperature (don't recall exactly when) but the end result was that the PEI curled up at the edges. It was a royal pain and then some!
    I love printing straight on glass ... no muss. no fuss, no adhesion enhancers, no divots in PEI. When printing with petg I need to occasionally replace the glass if my bed temperature is too high or if my squish factor is too high. Glass is a LOT cheaper than PEI.



  • @jens55 said in Layers do not stick together?:

    I have the same problem with my pertinax (?) plate. I tried some guess none of them was strong enough to hold the plate.
    The nice feature is the bendable layer, so you can pull it of the plate bend it slightly and the object pops off. Very convenient when you print large parts. But the price is a point.... And I have already some very very bad marks in it from tiny collisions with the nozzle. 😞
    But the bed PEI surface for my new CoreXY is already on stock. 😉

    Cheers, Chriss


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