Advice needed for conflicting problems

[Brian]

Hi all! I have been making a lot of small parts with great success, and tuned my Slic3r settings to produce the best results I possibly could. I have always had a bit of a problem with hairs and stringing, but I was able to follow the advice of others on this forum to get that reduced by lowering the extruder temperature. I never really got rid of stringing completely, but I found ways to orient my models such that when they were printed the strings were in places that didn't matter or were easy to trim off.

Most of my parts were pretty small and were mostly printed solid ABS with 100% infill because they were manly thinwalled shapes. I was pretty happy with those results.

Yesterday, I decided to make a simple solid base for a piece to sit on and so I made a cylinder and printed with the same settings except I changed Slic3r to 50% infill. The print was about 1" tall and 3" in diameter. I printed it last night and it looked good at the start but when it finished it looked like there were layer adhesion issues on every single layer. I could peel it apart like a stack of pringles chips. Some of the layers had what looked like strings coming from them but I think this was the actual extrusion peeling away when the extruder retracted.

I suppose the extruder temperature was too low and the large object cooled a lot and the subsequent layers didn't stick, and so I need to raise the extruder temp from the previous settings. But then I know when I raise that temperature, I get a lot of hairs and stringing and ooze. How does a person compensate between the need for low temperature to prevent stringing, and high temperature needed for layer adhesion???

My instinct is to do everything I can to eliminate the stringing and ooze of the extruder first, and then the other problem will take care of itself. Is that the right approach? If so, what factors OTHER than extruder temperature will cause stringing? What should I do to help get ride of it?

Also, would a different slicer print with less stringing than Slic3r? Should I try something else?

[Captain Starfish]

I'd approach it the other way around, myself. String and ooze are a pain but can usually be taken care of either with sandpaper/file/vapour after the job or eventually with appropriate tweaking of the retraction settings. And, if you have ooze or stringing problems, you still have a solid part. Layer adhesion issues mean you have a pile of useless rubbish, regardless of whether it's hairy or not.

Deal with the layer adhesion first, get solid but messy parts, then start hunting your ideal retraction, speed and cooling settings to sort out the mess..

[Mac The Knife]

Definitely increase the extruder temperature, But, have you tried different retract settings in slic3r? Someone had posted to increase the length of the retract, and retraction speed to help minimize stringing. I seem to recall PLA doesn't like it, and will jam, but ABS works. I'm currently using a 5.4 mm retract, with a 1 mm Z lift, with a speed of 200 mm/s. You'll find those settings in the Slic3r config folder, in the printer settings, under extruder 1.

[Brian]

I'd approach it the other way around, myself. String and ooze are a pain but can usually be taken care of either with sandpaper/file/vapour after the job or eventually with appropriate tweaking of the retraction settings. And, if you have ooze or stringing problems, you still have a solid part. Layer adhesion issues mean you have a pile of useless rubbish, regardless of whether it's hairy or not.

Deal with the layer adhesion first, get solid but messy parts, then start hunting your ideal retraction, speed and cooling settings to sort out the mess..

Thanks for the suggestion. I know I can pretty much eliminate the layer adhesion problems with a 10 degree C increase in extruder temperature. I get nice solid parts with more temperature, but tons more stringing. I also notice that if the part is "pointy" or small at the top compared to the base that the heat is too much and it gets a "gooey" look in the finished print. I can compensate for this by adding a pillar or something next to the object on the build plate, or by manually lowering the extruder temp as the top is printing. I typically try and orient the parts with the fatter side down so I get better bad adhesion and minimize warping.

I was sort of hoping that someone had invented a slicer that could figure out that the surface area of a slice was getting smaller and take action to adjust things so that I don't have to fudge it manually.

[Brian]

Definitely increase the extruder temperature, But, have you tried different retract settings in slic3r? Someone had posted to increase the length of the retract, and retraction speed to help minimize stringing. I seem to recall PLA doesn't like it, and will jam, but ABS works. I'm currently using a 5.4 mm retract, with a 1 mm Z lift, with a speed of 200 mm/s. You'll find those settings in the Slic3r config folder, in the printer settings, under extruder 1.

I had tried some retract settings a while ago and I don't think I ever tried changing the speed. I tried adding a wipe and z-lift and as much as a 10mm retract. I always get stringing or ooze. Is this related to the Bowden tube extruder in any way?

Not long ago, I was trying to quantify the issue and did some experiments. What I tried was to manually extrude a few cm of ABS into the air and then pull the extruded piece from the extruder by hand so I could see what needs to be done to snap that hair off when the extrusion ends.

I tried all sorts of temperatures and retraction settings, as well as trying pulling the extruded piece off at various angles (parallel to X, Y, or Z. I tried it with the layer fan on and off, and really no matter what I did there wouild always be alittle spider web sized hair formed as I pulled the plastic away. The only way I had any luck with was to pull it out and form a hair and then pause and pull again and the hair would break off because it had cooled.

I don't think any slicer generates g-code to work like this. It may be that the technique only works when extruding into the air and when you actually are printing a layer then it fails. I have no way of knowing.

I was kind of hoping that there was some extruder adjustment or tweak that would reduce this.

I might try a smaller diameter nozzle to see what that does.