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RayLivingston

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  1. That makes sense. I did not print a brim, as it was not necessary for the smaller parts. I'll try one of these big ones again with a brim. Thanks! Regards, Ray L.
  2. The printer is a modified Tevo Tarantula, and I'm printing with PLA. Only one extruder, and using the same termperiatures I've used for many other smaller parts. This has happened on two different larger parts, so it is a consistent problem. Smaller parts do not exhibit this problem. Regards, Ray L.
  3. I'm doing some large prints, and have a new problem - the edges of the first few parallel perimeter layers are curling up, rather than adhering to the bed. This means what should be a square cornder in the cross-section ends up becoming a rather large radius fillet. The center "in-fill" layers are adhering just fine, and I don't have this problem on smaller prints I've done. The rest of the print, which is 1/2" thick, prints absolutely perfectly. One difference that may be a factor - I've set the Shell->Wall Thickness to 3mm. Could that be the problem? Regards, Ray L.
  4. VERY helpful. The re-design of my part has completely resolved my problem and the new parts print perfectly. But I'm sure I will run into this problem again, so the above information will be very helpful in resolving those future headaches! Thanks! Regards, Ray L.
  5. Thanks for the info. The printer I was given has the fans wired on all the time. Perhaps I'll try to re-connect them for computer control, and see if that helps with bad plate adhesion. I've decided to re-design the part to eliminate the thin walls that are causing the problem. The timer per layer setting also sounds helpful. I looked for something like that, but did not find it. I'll have to look again. Regards, Ray L.
  6. OK, I've played with this some more, and things are looking better. But.... While the appearance is greatly improved, and almost acceptable, the upper layers are still MUCH weaker than the lower ones, and it takes almost no force at all to break them off the rest of the print, while breaking the lower layers is extremely difficult. Those areas are still (visually) much less dense than the lower layers, hence much weaker. There is still a distinctly visible line at the separation between the two areas, and that is exactly where it breaks when stressed even the tiniest bit. Regards, Ray L.
  7. As a quick test, I simply ran two of the parts at one time, and the result was greatly improved. Still not perfect, but MUCH closer. It's not clear to me how much cooling is "right". Is the idea for the part to be fully cooled before the next layer is extruded, or is there a range of temperatures that is good for putting down another layer, and anything out side that range, whether above or below, will cause problems? The fan on my printer is currently on all the time, which, for most designs, works very well. Is there a real advantage to having the fan actively controlled during the print? Regards, Ray L.
  8. That makes sense! It is small-ish. The OD is 1.8". I will add some extra features to make it take longer, and let you know what happens. Thanks! Regards, Ray L.
  9. Here is a photo of the part. As you can see, the lower part printed fine, but the upper is awful. Regards, Ray L.
  10. I have a TEVO Tarantula, with modified extruder and hot end, which is capable of producing really excellent quality prints. But I'm finding for certain kinds of features, the g-code being created by Cura gives really terrible results, and don't know why. Here is a link to the Fusion360 model for my current part: https://a360.co/2Ts9cBH Note that the model consists of three different cross-sections: Bottom "plate", 1mm thick. This prints perfectly. Lower profile, ~4mm thick, which consists of two concentric rings, each 0.040" wide, with a 0.040" gap between them. This prints perfectly. Upper profile, same as lower profile, but with several segments of the two concentric rings removed. This prints horribly. The bottom "plate" and "lower profile" both print 100% perfectly, every time. They are very solid, excellent adhesion between layers, and dimensionally dead-nuts accurate. The upper profile is a complete mess. Surface finish is awful, and looks like too much plastic was extruded, at too high a temperature, with no more than ~50% fill. This whole area is very weak, and very ugly. I'm sure this is a matter of settings, but I've been unable to find any that make a substantial difference in quality. It appears to me the problem is in the way it forms the walls. On the lower profile, it does mostly nice, concentric inner and outer walls, then a single line right down the middle between those two walls. On the upper profile, it alternates between a single line down the middle, and lots of very thin, parallel diagonal lines jammed between the two walls. The g-code file is attached. The problem area starts at layer 25, on line 25519 in the g-code file. This is being done using the "normal" profile. Normal.gcode
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