Morning All,
Attached are images of a part I am printing. For some reason the top layer is splitting as shown in the picture. Its PLA at 0.3 layer height on the robo 3d printer R1. It seems to be related to top layer infill on larger flat areas.
I haven’t changed any printer settings since I could print something like this and its appearing across spools so I am guessing its a mechanical issue. I am printing a 3"x3" flat plate to see if I can catch it in the act. Anyone seen this before?
Ok time to clarify:
It looks like its a fundamental issue of my top layer not adhearing well to the one below it. I have attached two more images of the square I printed this morning. The one in the clear light of day really showcases the poor surface finish on the topmost layer. I’m suspecting the following:
(1) I am extruding too cold (180c) but if so I would expect so see errors other than my top layer
(2) A partial jam in my nozzle. If so again I would expect to see differences in layers other than the last, top one
(3) Something fan related. I am not sure what but historically my fan has strived to ruin my prints.
First off, I would recommend printing with a 10% or higher honeycomb infill. Also, make sure your top layer is printing at about half of the speed of your regular speed. Another thing that you should check is your top layer extrusion width. If it is too wide, it could be causing the top layer to warp more while cooling. The primary suspect IMO is that it looks like there is 0 infill, causing the hotend to pick up filament it already extruded and displace it.
TL;DR - Print with 10% honeycomb infill, that should fix it. If not, Raise your temps to 195 or so, The plastic gets very stringy at 180c
Best of luck, Will.
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Sorry I didn’t post my setup. All pictures are at 100% rectilinear infill (to eliminate infill as a variable) with 3 rectilinear top and bottom layers each. Top layer speed and width are default to repetier but I’ll get exact numbers when I get home.
I’ll also check my nozzle when I get home. I didn’t see anything obvious that would muck everything up but that doesn’t mean there isn’t something there.
I’d like to avoid raising nozzle temp for several historical issues I had with my printer. I think it would masking the problem even if it did fix it because I didnt change my nozzle temp from the last print that was successful to this print which isn’t. Its good advice though. There always seems to be a price to pay for “too hot”/“too cold” and no such thing as “just right”.
Thanks Will
watch your printer during a few solid layers, preferably the top, and see if the nozzle is staying clean or has filament blobbing up on it. That way you can see if the nozzle is dragging around some of the plastic its already extruded.
I have some pictures showing exactly that time but they came out terribly so I’ll try with a picture with words: Lets call the top layer 0, the one below that -1, then -2 etc. It looked like layer 0 never adhered as well to -1 as -1 did to -2. 0, -1, and -2 are all using the “top layer” setting as I print with 3 layers top and bottom. layer 0 looked like it kept a uniform distance from -1 as it was laid down but immediately raised (or didnt) immediately after the nozzle left it. Whether it stayed down or didn’t seems to be related to its distance from the perimeter (see image 1), the closer to the surfaces center, which I am taking to mean the farther from the edges, the more pronounced the striations and where there is very little distance between perimeters there is no problem.
On a side note I just spent a week calibrating my bed and this appeared directly after that but I don’t see how that could have an effect. It was all mechanical leveling, never touched the software.
Seeing as you dont want to change your temps, try a thinner extrusion width (only for top layers). And perform a cold pull on your nozzle to clean out any gunk that may be causing your extrudate to curl.
So I manually cleaned the nozzle and fans this morning along with clearing the extruder using the atomic method. Unfortunately it was with black pla so I cant comment on the discoloration but to get a clean shape it took 2 or 3 heat-and-pulls. I did a test print and it turned out well. I’m going for the big part originally pictured now and I should know by the end of the day if its fixed. I’ll post to this thread with the results.
On a side note does anyone have problems using the atomic method of nozzle clearing with 1.75 filament. 3 it works great but every once and a while with 1.75 it’ll snap higher up and jam the nozzle. With the Robo3d nozzle removal isn’t that bad but still its really frustrating.
Ok so that didn’t solve the problem. All fans are running well, nozzle is clean inside and out and still theres an issue. I’m going to try turning the heat up and see what results that yields.
