LindsayPatten

This is very similar to the issue I had in a previous thread Getting inner and outer parts of a wall to print consecutively If you look at the preview you can see that it does a long non-retraction travel to the z-seam position for the outer wall: It's the light blue, non-retracted travel, coming in from the right. The best solution is to change your settings to get a retracted move, which will show as a dark blue line like the one going to the left. More of a workaround until someone more knowledgeable chips in, you could move the seam to the inside: Here's another thread about the same issue: The solutions there were to reduce the loss of filament due to oozing by reducing oozing 🙂 For example, using a lower extruder temperature or use a dryer filament... or tune your retraction settings to prevent oozing which is what worked for me.

As a follow-up in case anyone else runs into a similar scenario: After reading more about the causes of delamination/layer separation I found out that residual stress (aka internal stress) caused by material shrinking as it cools scales with the size of the print. For any given set of number of perimeters, infill, etc., there will be a maximum size that you can scale the model to before residual stress will cause problems. As a model gets taller the heated build plate can't heat the whole height of the print so that doesn't help. So it's not surprising that even when I got everything working at half scale there were problems when I printed at full scale. In my case increasing the wall line count was how I got a successful print. Increasing wall count for the whole model added too much weight so I used support blockers with per model settings to only increase it at the leading and trailing edges. The model has 3 wall perimeters generally and I still got a small delamination adding 3 additional wall layers on the leading and trailing edges so I gave 5 additional walls a try and that was successful. I should try 4 additional walls but each model takes almost half of a 1kg reel and I've wasted multiple reels already so I'm sticking with 5 for now. I'm still a little surprised that three additional walls, for a total of six, was insufficient but I guess it goes to show how strong residual stresses on large parts can be. The model is 247mm tall and 358mm long. I also added two-layer "mouse ears" at the bottom to combat warping away from the build plate as brims alone weren't strong enough to stop that.

As it happens I am using Grid infill already, although it is interesting that when I used Lightning infill there wasn't any delamination. I'm still chewing on that. I've actually got the model and side fans turned off and have the back (vent) fan at 10% to keep the ambient temperature around 41 deg. Wrt small scale testing that's exactly what I did, although it still took me almost two reels of filament to figure out that even though the filament guide says 240-260 that it actually needs to be 270, and that even though I've never used glue for printing PLA or PETG, for ASA prints of any size glue is essential. I no longer have problems with small scale stuff but when I print a piece that takes most of the diagonal size of the printer I'm getting serious delamination on the front and back tip. I realized this morning that I had the z-margin on the trailing edge, which is aesthetically the best but possibly contributing to delamination on that edge. Before I had that insight I created and started a print with an extension of the trailing edge out to a cylinder which should be less delamination-prone and is easy enough to remove post-printing. I printed off a partial height section of the blade with that and it seemed to work. In another 10-20 hours we'll know if it works for the full height piece. I printed the test at 275 deg on a 105 deg plate with reduced speed, and reduced the layer height to 0.16 from 0.2, so we'll see if that combination works for the full piece.

I thought I had figured out how to avoid delamination when I was printing half-size prints of this model in ASA, but when I printed it full size (246mm height) delamination reared its ugly head again: I increased the bed temperature to 105 and decreased print speed from 125, 100 to 100,75 (inner wall, outer wall) which decreased the number of delaminations slightly but... I'm printing at 0.2 layer height, 270 degrees and keeping the ambient temperature at a steady 41 degrees. It's an airfoil shape with a fairly sharp trailing edge which is the hardest to avoid delamination with but it also starts on the leading edge. The filament label says 240-260 but I couldn't avoid delamination on the smaller prints with less than the 270. I might try 275 and/or 0.15 but I'm wondering if there is anything to do with infill that might help. Or adding some additional reinforcements or something. Any advice?

Thanks for the reply. In Cura the default accelerations all seem to be 500 already. I can't find anything on how to set max acceleration on the K1 Max itself. Unfortunately, the main part is a helical blade that twists over its length so aligned at the bottom means not aligned at the top, although I guess I could use a support blocker thingamajig to deal with that. Isn't it a bug though for the print head to go to the far end of the print do nothing and then come back? (Sorry if I'm not very coherent, I'm being rushed here)

I've got a part I've been having a hard time getting to print on my Creality K1 Max until I reduced printing speed to half of normal. While it was printing the bottom layers it would travel back and forth so much that the printer would lose its origin and start printing in an offset position when printed at normal speed. At half speed it would print okay, and in fact once it was through the bottom layers I could raise the speed back to normal and it would print the middle layers okay. While watching it it seemed to me that it was jumping around the print an awful lot more than seemed necessary so I looked at the preview of the bottom layers in Cura and saw that there are what appear to be a large number of unnecessary travels most of the way across the print and back, here's layer 2: If I step through the animation there are actually a ton more unnecessary travels that don't show in the image because they trace the same paths repeatedly and/or trace the wall outline repeatedly. Any idea why it is jumping around so much? It is Cura 5.8.0. CK1MAX_Cowl60x10PlusTol.3mf

Thank you very much Slashee! Changing Maximum Skin Angle for Expansion to 89 seems to fix everything. As it happens I had to abandon use of Lightning infill as some of the larger relatively flat walls were warping when they didn't have infill to hold them in place. It worked well when I was printing the models at half size but I guess large areas of thin walls probably can't be expected to stand completely on their own. At least with ASA which is prone to warping. I wonder if the default value for Maximum Skin Angle for Expansion ought to be 89 by default? It seems to me that one shouldn't encounter anomalies when using the default values. I don't see anything unique about my model that it should require changing somewhat obscure slicing parameters in order to make it print cleanly. As you noted, the issue also occurs with the other infill patterns and I wonder if it isn't occurring for many models without being noticed because it is obscured by the infill. I may have only noticed it because the Lightning infill provides unobscured views of the interior? Anyway, thanks again for providing a workaround, I doubt that I would ever have been able to figure that out on my own.

While using Lightning infill there seem to be some extraneous bottom/top surfaces being produced: I don't see why it is generating the rows on top of the interior surface which is at 45 degrees if that's relevant. I'm not sure it should be generating "support" for the bottom interior wall but that isn't as strange and might be a good thing. Is there a setting I need to change? K1M_Blade100Bottom1.3mf

I've been having a lot of difficulty printing a couple of tall thin models, sections of a wind turbine blade, see my other recent thread for the project file, and having difficulty with getting top layers printing on top of infill when printing ASA. I don't have the problem with PLA but with ASA inevitably there will be places where it doesn't go on smoothly and bits of filament warp/curl upwards, and then the extrude bumps into these and, given the tall thin piece, knock it off the build plate. Having a largish model fail on the last few layers is pretty frustrating. As you can see in the image the density of the infill was already pretty fine and the problem still occurred. I've been able to get complete ASA prints using the lightning infill with 70% density and super slow bottom/top layers. It's pretty great how fast a print can go without infill but for final prints I need some infill throughout to give it some stiffness. I have a somewhat vague recollection that there used to be an option or something that caused the infill to get denser as it got closer to a top layer, is there such a thing? I've tried a few things with support blockers and per model settings but haven't found a good solution. Any guidance or ideas would be welcome!

Thanks for the time and effort you put into looking into this for me! The last two images in your post look like there is a bug in the code, hopefully someone will fix it at some point.

Perfect! Thank you very much! Edit: Oh, not quite perfect after all. Where the infill area is split in two by the hole for the pin the hex pattern in one of the areas jumps. It then shifts with each layer as the edge along the pin moves forward and then back. The picture below is from a different segment of the blade but the same thing happens with the first segment, except it doesn't jump so badly, it just moves to match the edge of the hole for the pin. It seems like it would be nice to have an option that tells it to keep the pattern fixed and not try to move it with the contours of the object, matching the way the grid pattern for example works. It seems that there might be a degree of circularity between the tile size and the infill density? Also, for Max Tile Size it says "This setting has been hidden by the active machine and will not be visible." Why would that be?

I have two questions about using the infill addon to create honeycomb infill: 1) sometimes, but not always, there are shifts in the alignment as shown in the attached image, is this a bug? 2) is there a way to scale the size of the honeycomb pattern? Infill density has no effect, unlike the built-in infill patterns. I'm using the 5.8 beta release because it has the K1 Max printer settings. Edit: after watching the machine try to print this I noticed that the shift is particularly detrimental to honeycombs as the lines connect at an angle so bridging material doesn't end up on the intended line, i.e. the intended end point of the line segment is hanging in the air so the extruded material gets dragged to the side rather than the intersection point. It took maybe 30 layers before it managed to patch itself up at the point I've circled. If I could scale the honeycombs to a smaller size this might not be as much of an issue. CK1MAX_V2BladeUpperThirdish.3mf

Just to summarize what I learned on this topic: * The setting Group Outer Walls in the Experimental section, which is enabled by default, when disabled accomplishes what I asked for, i.e. print the outer wall immediately after/before the adjacent inner wall when there are multiple disjoint wall segments. When in the default enabled state, Cura will print the inner walls of all the wall segments first and then print all the outer walls, hence the "Group Outer Walls" name for the setting. If you have Wall Ordering to Outer to Inner it will print all the outer wall segments first and then the inner walls by default. * The lack of retraction was probably the actual biggest contributor to my problem, naturally you get a lot less filament lost to oozing with proper retraction. I sent Greg a project file and he made some mods and sent back and, while they don't relate directly to the original question I learned two very useful things: * if you set infill height to twice layer height it only has to print the infill every second layer, which drastically cuts down on print time. This assumes the infill isn't playing a structural role. * you can use support blockers to easily cut the top off a model, similar to the way you can cut off the bottom by just sinking the bottom of the model below the build plate. My prints no longer have the problem artifacts so I'm pretty pleased. Thanks again Greg! P.S. One other interesting thing was that after making the setting changes Cura started printing the small fill lines before printing the wall lines, whereas before it would print one wall layer, do a big travel to print one of those small lines, another big travel back to the z seam, etc. so that it was doing two large travels for each one of those small lines: With four of the little fill lines this eliminates six or seven of the eight large travels. So, a lot fewer travels and much smaller artifacts from oozing.

Thanks for you continuing help Greg. I've sent you the project file. Here is a close up picture of the problem area. There isn't actually a blob there, it is all "missing" extrusion due to material lost to oozing during long travels. Where the wall narrows where the strut enters the blade, Cura fills the narrowing area with V shaped wall layers with a short single line at the bottom of each V that fills the space to the next larger V. Unfortunately, it runs around the perimeter of the blade, then travels halfway across the print to add that short little line, then travels halfway across the print back to where it starts the next layer of the wall. The short little line probably doesn't get printed at all due to the oozing during the first travel, and then the start of the next wall is even worse due to the two long travels. I guess one could manually edit out the travel and the short line and the next travel. Shudder. Ideally, Cura would change the V plus line to continuing one side of the V to fill the area where the short line is and then do the small travel to start the other side of the V. The material is Amazon Basics Silver Silk PLA. The final print will be in a more durable material, probably PETG. The bed heater on the Kywoo3D Tycoon IDEX that I'm printing this on isn't working so I'm stuck with PLA for the moment. The silver silk PLA gives a nice metallic look and the shininess really highlights any printing issues. I am just doing prototypes at the moment to determine where the mechanical failure points are. There isn't anything really proprietary involved, it's just a personal learning project, I've always been fascinated by wind turbines so I'm having fun building one now that it can be done without needing a lot of equipment or composite fabrication expertise. The blade is just a standard NACA 0018 profile helical blade. If I ever produce anything workable I'll post it on thingiverse or someplace. The most common failure mode seems to be for a part to split between two layers so I'm using a higher temperature to get stronger interlayer bonding, which probably contributes the amount of oozing. It isn't actually retracting during the travels so maybe I need a kick in the head and then figure out how to get it to retract in this circumstance.

Thanks again Greg! Yes, some complication always seems to rear its head. 99% of the print below went very well but in one place, for several layers the slicer had all five layers of the wall, each starting at the trailing edge of the blade, be preceded by a long travel creating an actual hole in the print due to the filament lost to oozing. In this case all the travels are a result of the area where the wall is thinned by the slot in the wall. I'm guessing that I will have to "handle this in post processing" but if anyone has any ideas I would love to hear them as I've got a bunch of these to print.