Over extrusion only on solid infill

This is a very weird issue I have from the beginning and now that everything is calibrated correctly it is becoming just annoying and even more unexplainable.

I have a Prusa i3, with Marlin 1.0.2 and using Slic3r 1.2.6.
I'm using a .05mm nozzle, 3mm ABS filament and printing at 250º (if you have delamination issues, up is the only way to go!)
I am confident the printer itself is fine!
Firmware configuration is also correctly calibrated.

So what I have been trying to do is fine tune the Advanced section on Printing tab of Slic3r, changing the percentage for top and solid infill, but with no success. When the print start looking good with freaksh low values, all hell breaks lose and the infill gets severe under extrusion symptoms.
Small printing areas are impossible to print correctly since it looks like molten lava going everywhere and building over itself.
Totally solid prints are simply a no go, nozzle stumbles on previous layer deformities after a few layers making the motors skip steps.

Yes, I already had this problems before printing at this temperature, if anything it helped a little.

So, what you fine people would try on my place to fix this blood issue for good? I'm out of theories.....

Man I feel like an old salt! Even though I'm not... I just have really been beating my printer up and getting all these same problems.

Here's what I did to fix this: in your settings, set z offset to something like .15 and try a print with all other settings normal.

Well....I don't think this should make any difference at all....

"Z offset can be used to compensate for an incorrectly calibrated Z end-stop."

Exactly what I would expect it to do, but my problem is not on the first layer, it's on every other layer after the first
Should I understand that, in reality, what this field does is add "0,15mm" to every Z movement?

I am working through the same kind of issue... please post when you come to a solution.

My current theory is that my Z steps/mm is set wrong.

I tought about that too, but calibration prints are the correct size and when moving 10mm on Printrun it moves the correct distance. Besides, perimeters and parcial infill are printing very well.

Ok, I'm not an expert, but I play one on tv.. j/k

If your first layer is too thick and second layer gets mashed, a solution is to start a tad higher, thus z offset. yes, this is compensating for improperly setting z in the first place...

but in my experiences recently, i was having this problem where the first layer dries and hardens, with some uneven surface, then second layer is too close and the nozzle hits the uneven parts and possibly skips.

i used the .15 trick temporarily to over come this, then i decided to work on my bed and make it more rigid by using better bearings and two zip ties per bearing (wish i had those bearing pill box things that screwed to the bed) now i dont have to use the offset hack and have near perfect first layers every time with the auto bed levelling and z probe. it's not mounted on a servo, its just a stick i attach to the hot end carrier.

Edited 1 time(s). Last edit at 06/06/2015 02:11AM by thetazzbot.

WOW!!!

First, thetazzbot, I tried your idea but made no difference, I have problems on ALL solid layers not only on the first/second.

frankvdh, check the annex, it's a 10mm cube. Print it and measure, it's the best way to be sure.

Ok than, I started trying some "silly" ideas.
If your prints show signs of nozzle scorching or dragging, try this out. Take the hotend nozzle out and to sharpen it!
It's not the ultimate solution as I expected, but it really made a lot of difference.
Don't know exactly why though.....in my mind, a nozzle that flattens the the print trail should be better.....but it's not.

Try it out and let me know what happens, I'll keep trying some other stuff.

I've been experimenting a bit...

It seems that part of the problem is that my filament is quite a bit bigger than the nominal 1.75mm.

I also have (supposedly) 0.5mm nozzle. I'm not 100% sure though, it being cheap Chinese. I suspect it may only be 0.4mm.

Maybe also part of the problem is slop & movement in my linear bearings causing Z movement of the head. If you're printing one layer in one direction and the layer on top is printed 180degrees different, slop in the bearings could mean that on the second layer the nozzle height is too high or too low.

So, I've fixed the bearing slop, cut down my flow rate to 80%, and changed the nozzle size in Cura to 0.4mm. That seemed to be working well, right up to the point where my USB cable stopped working

@aFrazatto: When you say to sharpen the nozzle, what exactly do you mean? File down the nozzle at (say) 45 degrees? Which would make the nozzle slightly shorter?

Mine was flat on the tip.
I used a Dremmel to take the edges of, making it less blunt.

Playing with this a bit now...

One thing I noticed was that manually issuing 3-4*5mm retracts followed by 4-5*5mm extrudes seemed (usually) to clear the problem. I also tried running the print with the nozzle 10mm above the bed and it still clogged! Once cleared,

So I think my problem is nothing to do with nozzle height... it's something happening inside the extruder.

I've tried changing the temperature from 180, 185, 190, 195, 200, 210, 220, (PLA) but the same thing seems to happen every time.

Varying the flow percentage between 80% and 120% didn't seem to change things.

I read elsewhere that the proper setup for an E3DV6 was to tighten the nozzle, then back it out 1 turn, before tightening the heatbreak into the heater block. So I tried that (previously had the nozzle tightened all the way in), but still no joy.

I ordered some cheap nozzles from china some time ago and they are all in the bin now.
Compared to the quality ones bought locally I found several issues:
1. The holes drilled are anything but the stated diameter.
I checked with dental wire (which has a well defined diameter) and the 0.3 was actually 0.35mm.
The 0.4 was actually between 0.3 and 0.35mm - could fit the 0.3mm wire quite loosely but not the 0.35mm.
2. They require checking and cleaning before installation.
My nozzles all had a wax like coating and several burred areas on the thread.
3. Worst problem however is the lenght of the nozzle hole.
It should as short as possible to prevent pressure build up and ensure a good extrusion.
On my nozzles the holes were over 3mm deep before finally reaching the melting chamber.
4. They are quite long....
With the thermistor mounted in the heater area and not directly inside the nozzle, the temp down at the tip can be up to 15° C below what you see in the printer software.

I now use short "stubbies" with the thermistor directly mounted into the tip and all is good.
With cheap nozzles my extruder was either close to breaking point or there simply was never enough material extruded no matter how I changed the settings.
If you have the right tools and skills you can check the length of the extrusion hole and drill the melting chamber so deep that less than 1mm of material remains.
The fine hole might need a clean out drilling after that too.
Depending on how the brass was treated you should heat it to a slight glow and let it slowly cool down.
This way the brass get much softer and is easier to drill.
When finnished do the heating again but dump the brass into cold water to harden it.
After a nice polish you are good to go hopefully.

After a whole lot more experimenting, I'm now printing again

For other people suffering through the same issues, here's what I learned...

Probably the most important thing I did was to fix some play in the Y-axis carriage bearings that was allowing/causing the head to move up and down. I think what was happening was that the nozzle would be too low in some places, rub on the previous layer and produce back-pressure inside the hotend, which would then clog.

I did also change the heat-break and then the nozzle... changing the nozzle seemed to make some difference. Because I did that, I recalibrated my extruder rate, and found with the new nozzle that I needed to set that down to about 75% flow rate. Possibly that might also have worked for the previous nozzle.

I also found that there were some kinks in my filament, and occasionally these would bend *around* the toothed part of the extruder drive gear onto the smooth part of the gear shaft. I added an extra filament guide so that the filament can only go vertically into the extruder drive.

I also tweaked the pressure of the extruder against the filament... I think that ideally you want this to be set so that if there is a temporary jam in the extruder, the motor will skip a step rather than grind away some of the filament, or push more filament into the hotend. My thinking here is that a jam might be caused by a high spot on the bed or output... the motor can skip some steps until the nozzle is clear of the bump and then start turning again. That's much better than grinding away filament so that no more filament is extruded, and also better than pushing filament too hard into the hotend and clogging it. I have noticed that my extruder motor *is* skipping steps here and there, especially on the second & third layers of a solid fill.

And finally, I noticed a couple of times that sometimes the filament tangles itself up on the spool... when the Y axis moves back, it pushes the filament towards the spool, which loosens the next 2 or 3 turns on the spool. If the last turn gets pushed underneath one of the others, and the other turn tightens first, the last turn is locked and now can't feed. I haven't figure out what to do about this, although my extra filament guide has partially solved it. The extra filament now tends to bow out a bit between my filament guides rather than pushing back to the spool.