On Sunday 21 February 2021 17:15:45 Chris Albertson wrote: > > 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. > > That might explain a problem.The purpose of the fan is not to cool the > nozzle but to cool the plastic that was just laid down. It has to > work equally effectively if the nozzle is moving left or right > > The idea is that the plastic needs to be liquid while inside but needs > to turn solid just as soon as it is maybe 1/2 millimeter from the > nozzle tip. I think the first shape might have been better. The > general > area around the nozzle is what needs the air, not on the nozzle > itself. > > This is why the printer is able to print moderate overhangs and > bridges, the fan cools the plastic before it has time to fall.
My thinking is along similar lines, but includes the fact that we are looked at the hot blocks temp, not quite the nozzle temp, particularly if that fans air flow is aimed at the nozzle, that the nozzle tip may be 10C or more below where the thermister is measuring the hot block. 1/4" or a bitmore from the tip of the nozzle. Anyway, I just pulled a sprocket off the bed that is still about an RCH small, but I've raised the X & Y scale about .1 a couple counts at a time which has succeeded in making its fit on the old alu procket being used for a hub be a little schloppy. So I just resliced it starting with a .1mm smaller hub hole and raised the scale another .03 in both dirctions to see if that fits. And the fan speed is at 30% in cura, just enough to make is spin. And the sprockets are fairly solid with the flow at 90 % of 274. The microswiss is clamped down 2 or 3 times tighter than the guy at microswiss recommends, so there's considerable pressure in the nozzle. But with my hot end mods, very little hot block heat gets to the filament until is actually inside the nozzle, it has the capricorn tube around it all the way to the back face of the nozzle. So there is less than normal time for it to get melted. By shutting the fan down, the infill rip up has ceased, and the laydown is much cleaner, including the top flange which was hanging out in the breeze at an angle, now its clean with that fan running at only 30%. So now I can concentrate on getting the right size. Which I'm closing in on. I started with almost a tooth too small with half a turn of belt wrapped around it. I ordered another printer, the best Dremel last Saturday, supposedly had to be here to sign for it Wednesday, but the storm has shut down traffic, so now its 8 days, 6 of which its been showing as out for delivery on the tracker, and still no guy in a brown van banging my doorbell. No bad stuff for the next couple days, so if it doesn't show by tomorrow night I'll see about a reship for free. I'm an old Iowa farm kid, this weather would not stop me if I needed to go, but UPS making their drivers responsible for every rock chip in the paint on the truck/van they are driving also makes them cautious to a fault. Weston was also in a sweet spot, getting 5" when all around was up to 18" plus. But I'm just off of I-79, and I know they've plowed that, had it clear by last Wed. evening. As was the road in front my place. But then it hit us with another one just like it. Wiped out the rest of the week... 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
