Help with random PLA layers printing poorly

Hey guys,

This is my first post, I've been reading all sorts of stuff on here for months now and I appreciate the help you didn't know you were giving me.

I have an 8" MakerFarm Prusa i3v with a .4mm hexagon head that I've been playing with for a few months now and I'm running into some trouble.

Here is a picture of my part:



This was printed in PLA at 50 mm/s 195C for the extruder and 70C for the bed. I sliced it with Cura.

Previously I used slic3r and was printing more in the 220C range with pretty good results. I was using purple filament from Makerfarm and my problems started when I ran out of purple and switched to Orange. The orange is also from Makerfarm so I would've assumed it's the same stuff but I haven't had good prints since. After awhile, slic3r began pissing me off and now I made the switch to Cura and I already like it better. The part above is my first Cura print. My first guess was to try printing at a bit higher temperature so I raised it to 200C and that's printing as we speak. A picture of that part is here:



As you can see there are still a few defects along the same lines as the first print but it is getting better. I'm hesitant to keep raising the temperature though because I was playing with a few smaller parts with overhangs and they began curling up severely at higher temperatures.

Do you think I need to increase my extruder temperature to eliminate the defects in the layers and worry about the overhangs and curling with a better cooling fan setup? Or is there another setting I can tweak to help with this? My only other thought is this is an extruder issue but I don't know what i would change there, I've been using the same version of a Greg Wades Accessible Extruder since I got the machine.

Thanks for any advice.

did you verify your temps with a meter? your extruder temp could be wrong.


also, your hot end could be dirty, but I'd also check to make sure that the spool moves freely, and that the issue isn't that the filament is getting stuck on the spool....

Did you measure the filament diameter? To me it looks, like you have underextrusion. Stepper skipping?
Or a clogged nozzle from dirt, like Qdeathstar mentioned.
Both symptoms get better with raising temperature, but that doesn't solve the problem.
-Olaf

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Qdeathstar
did you verify your temps with a meter? your extruder temp could be wrong.

I didn't verify them with a meter, I did make sure however, before printing these parts that the temperature sensors were firmly in place and would have no chance of sliding around. The number isn't really my concern as it should all be relative - it was the idea that if the temp was too low I got these results but too high and my smaller components were curling upwards.

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Qdeathstar
also, your hot end could be dirty, but I'd also check to make sure that the spool moves freely, and that the issue isn't that the filament is getting stuck on the spool....

This may be my problem. I just realized my filament spool is rubbing on the filament holder and could cause resistance when it tries to spin. I will definitely make some modifications regardless as to whether this solves my problem or not.

As for it being dirty, that could be a possibility. I did swap in new Greg's Extruder parts not too long ago and I make sure everything is clean while putting that all back together. I would also think that if it was a stuck piece of dirt or something that I would have some more consistency to the errors in the parts?

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o_lampe
Did you measure the filament diameter? To me it looks, like you have underextrusion.

I did measure the diameter with calipers. Cura was defaulted to 2.85, I measured 2.95 over 5-10 measurements. These were both printed with 2.95.

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o_lampe
Stepper skipping? Or a clogged nozzle from dirt, like Qdeathstar mentioned.

Is there a method to determining if a stepper is skipping? Wouldn't this also have a little more consistency with errors?

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o_lampe
Both symptoms get better with raising temperature, but that doesn't solve the problem.
-Olaf

I agree raising the temperature doesn't solve the problem so I appreciate the different suggestions. I'll make the modifications to the filament holder, re-measure the filament diameter, double check that the set screw for the extruder stepper is tight, and try another print. If that doesn't work out I'll take it apart and clean it out to verify theres no dirt stuck in there. Thanks guys!

i think this could help
[support.3dverkstan.se]

Thanks for all the help guys. I believe my problems are solved, but I don't want to speak to soon. After no luck re-measuring the filament, checking screws, and playing with retraction settings I took it all apart. I spent an hour with a zippo lighter making sure there was no debris left in the hot end and I also noticed there was a small rib in my printed extruder. I've gone through 3 or 4 Greg Wades extruders and between where the filament enters the hot end and the hobbed bolt I saw a vertical rib that ran the length of the filament channel. I got the dremmel out and drilled it out to make sure there wasn't any friction. After putting it all back-together and starting my first print, there appears to be a night and day difference. What I believe happened was a combination of friction spots and a potentially dirty hot end, that upon retraction, jammed up the extruder enough to cause a delay, miss layers, or back the filament up. I'll confirm once this print finishes. I appreciate all the responses!