MakerGear Forum

OK, I'm stumped on this one.

I had a nozzle clog recently, so I removed the nozzle, cleared the clog, and put the nozzle back, and went through The Drill:

1. Warm up nozzle and bed to operating temps.
2. Center bed.
3. Insert 0.15mm feeler gauge between nozzle and bed.
4. Loosen nozzle retaining screw.
5. Home Z-axis
6. Tighten nozzle retaining screw.
7. Print 2mm calibration cube.
8. Measure cube height. If not 2mm, adjust Z-axis offset in Simplify3D and goto 7.
9. Profit!

So once I get a 2mm +- 0.02mm cube, I can print, right? Well, everything seems to work fine until I get to printing layer #3, which over the last three print attempts has resulted in the filament peeling up like this:



If I'd seen this de novo, I'd assume the head-bed gap was too large. I suppose I could continue attempting to print with 0.01mm adjustments but I thought I'd see if anyone here could corroborate my diagnosis first...

You're under extruding. You can see it where the solid fill attaches to the perimeters around the keychain hole. This may be a function of the clog still being somewhat present, a deformed nozzle, choked drive gear, etc.

I bet the third layer sticks if you slow it down.

I'm pretty sure the clog is cleared-- it's generally easy to tell if anything's obstructing the filament, since it will tend to come out of the nozzle at an angle, rather than hang straight down.

(At least in my experience.)

I tried reducing the print speed from 4400mm/min to 3800mm/min, which got me through the third layer with a few visible artifacts at the edges where the print direction reversed, but the fourth layer-- a 20% rectilinear infill-- completely fell apart, with the head dragging around a tangle of un-adhered filament after just a few seconds.

Right now I'm trying again with the extrusion multiplier bumped from 0.9 to 1.0. We shall see.

Just when I thought that after a year or so I had this thing figured out!

Yeah, that's white too. Might want to up the temp a little. White filament needs about 5-7 degrees more juice.

Jules wrote:Yeah, that's white too. Might want to up the temp a little. White filament needs about 5-7 degrees more juice.

Yes, but...this is one of those insanely frustrating times where you've been printing with this filament for MONTHS and NOTHING ELSE HAS CHANGED and SUDDENLY YOU CAN'T PRINT.

(Still, what the heck...never knew that about white filament...)

dramsey wrote:NOTHING ELSE HAS CHANGED and SUDDENLY YOU CAN'T PRINT

Have you successfully printed the same model sliced with the same parameters?

I ran into a situation a while back where some weird combination of model geometry and slicing parameters produced a severely overstuffed second layer:
https://softsolder.com/2016/04/13/overs ... ging-fail/



The fact that I'd successfully printed several iterations of almost the same solid model using pretty nearly the same parameters had no bearing on the problem. I couldn't reproduce the problem in any test object, no matter what I tried, so I eventually tweaked the slicing parameters for that model to make the problem Go Away and moved on.

Unfortunately, model geometry, slicing parameters, firmware execution, and plastic properties occasionally produce weird corner cases like that. The only solution seems to be gently adjusting the slicing settings to push the problem out of the way; dramatic hardware or firmware changes will probably mess everything else up.

I blame it on solar flare activity.

ednisley wrote:

dramsey wrote:NOTHING ELSE HAS CHANGED and SUDDENLY YOU CAN'T PRINT

Have you successfully printed the same model sliced with the same parameters?

Yes. Aside from removing the nozzle, clearing the clog, reinstalling the nozzle, and re-gapping and leveling, nothing has changed-- that is, none of the profile parameters used successfully before (well, until I noticed things weren't printing and starting playing with stuff. This is all PLA, by the way. And the same spools from the same vendor that printed well before.)

I have printed hundreds of these little fobs for organizations and friends. This current contretemps occurred when I tried to knock out a quick HP logo fob for the calculator conference I'm attending next week.

I think this is the most intractable problem I've had since beginning to use the M2 about a year ago. The only thing I'm reasonably sure of at this point is that it's not a head spacing / bed leveling issue. The symptoms are identical regardless of where on the bed I print (center, corners, etc.) and seem relatively insensitive to Z gap-- even when the gap is so tight the first layer prints with a trough-shaped bead, the results are pretty much the same as printing high enough to get a "correct" bead.

I initially disregarded the possibility of extrusion problems since the filament appears to be flowing straight and freely from the nozzle at the standard profile settings of 0.35mm nozzle width (although it's really 0.4mm, right?) and an extrusion factor of 0.90. Perhaps someone can tell me if this is the correct appearance of the filament for the first solid layer over a 15% infill:



Maybe it's the filament! No...



Other things I've tried:

-- Bed leveling (many times) and calibration cubes to set Z offset
-- Bed temps between 60 and 70 degrees
-- Extruder temps between 205 and 215 degrees
-- Extrusion factors 0.90 and 1.00
-- Nozzle width settings 0.35mm and 0.40mm

At this point I'm giving up for the nonce-- I've got to get ready for the conference and frankly I need the break for my mental health. But I'll be ready to try any suggestions when I return.

P.S. One other symptom, which I don't have a picture of but happens almost every print: when the head moves to first start printing a line on the bed-- like the first part of the fob after printing the skirt-- the first few mm of filament almost always pull up off the bed as the head moves. Imagine a "tail" 2-6mm long curling back up over the rest of the line, as though the initial bit of extruded filament stuck to the nozzle and was pulled as it moved.

In light of everything else, I'd wager that the nozzle is still partially plugged and you're not getting enough extrusion to get adhesion. How thick are the extruded strings on a failed model.

Hard to say, but using my digital calipers it looks as if a single strand averages about 0.42-0.44mm.

I have a new spare nozzle that I'm installing now...