The "nozzle fan" is actually a "part fan", used to cool down some plastics, especially PLA, that have a low (50c) transition temperature. Cooling the nozzle, and heat block is bad; that's why they make silicone "socks" to cover the heat block and nozzle.
You may want to try printing without the part cooling fan coming on for PETG, as it sounds like those first layers worked well. -----Original Message----- From: Gene Heskett [mailto:[email protected]] Sent: Sunday, 21 February 2021 4:22 PM To: Scott Harwell via Emc-users Subject: [Emc-users] Getting schmartder about 3d Greetings 3d printer folks; Trying to make a good 83 tooth gear for the A axis on the 6040 gandty mill, I could get a beautifull laydown for about 2 or 3 layers, then it got porous and quite lumpy for the test of the build, and it finally dawned on me that that is about the height cura turns on the nozzle fan. But one of the first mods I made was to replace the chute that directs that fans air in the general direction of tyhe nozzle, with one I printed that aims the air directly at the nozzle with its shape. I figure that also might explain why I have to run the nozzle at 245 to 250C. And I occasionally get burned filament blobs. Then I noted cura has a 215C setting for generic PETG So I went down to 230 and essentially froze it up. So as a midprint experiment, I went into the merlin menu and set the max fan speed to 90, 255 is wide open, which is about the minimum it will even start. The ejector was clicking because it was slipping, but 10 seconds later the clicking stopped, the fan, with that snoot on it, was too much. So now I've also dropped the nozzle to 238C, and I can probably turn the flow back up. And one layer later, I am seeing the line by line laydown again but the lumps under it are showing thru. Who knows, I might eventually learn how to drive this thing yet. Maybe I can get it to flow at 215C but that would be with the fan turned off I expect. cura doesn't say. The roads to Weston WV are still too slick for UPS I guess, the $1900 Dremel printer that was supposed to be here last Wednesday, is still showing as out for delivery at 4:07 Wednesday morning from Thornberg PA. Wherever that is, I've not seen a turnoff with that sign on it in the last 32 years of running across PA to near Ithaca NY. If it doesn't arrive Monday, I'll see if I can make Jeff send me another. Here in Weston, the local roads don't seem to bad to this old Iowa farm boy. They have not been so bad they would have stopped me if I need to go for a script or groceries, and I don't even have chains for this 4WD truck. However, most WV drivers would probably use me for a target to T-bone so I've laid low. And can for about another week according to the freezer. Stay safe and well folks. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
