Hey guys im back with another question.

Hey guys im back with another question. Since my last post ive had great prints but my last two prints are ending up very strange( look at the pics). anyone know what this is, i thought it mighr be the hotend temp but im printing a 175 for pla and my other print seemed fine( last pic ). any thoughts?

How is the humidity in your area? Is it the same filament? How much time in between the prints? Could you have a partial nozzle clog?

Looks like under extrusion. Are the old good print and the new ones from the same g-code file?

A few possible things to check:

As mentioned already partial nozzle clog.
Driver gear full of chip or worn out
Cooling issues with the extruder
Damaged PTFE tube is you have one in extruder.

How does the filament strand behave as it is extruded hot under a “load filament” type command?

@NathanielStenzel yes the filament is the same theregore humidity isnt the problem. they where printed with about 8 hours in between. i doubt that is is a clog as it only hapens after a cerisn hight print. ive seen this before but this is an all time bad

@Jeff_Parish yes they are both the same g-code. i checked the direct drive and it looked fine i cleaned ut just incase im mid print right now and i slowed the speed just to see what happens. im printing with a original e3d v6 so i doubt a extruder problem though i have noticed it getting hotter around the heat sink. for your last question i dont understand? for loding fillament i just manualy load it through the cura advanced functions…if thats what u mean

Check your filament diameter. It may be smaller in some spots.

@Mark_Fuller good thinking. i just checked it eith calliper and it actually seems to be bigger. like 1.76 in dome spots. eill that mske a big difference

If it is after a certain amount of time or around a certain height (linked together) it is likely heat related under extrusion. Could be heat creep if your heat sink is getting warmer. Differences in diameter + /- 0.02 won’t make much difference at least not that drastic.

Do you have an option to load the filament continuously so it just produces a long straight strand while it is hot? I use a similar function on my printer firmware to watch how the filament comes out. Gives me a pretty good clue to if the temperature is right or if the gear is clogged based on how the strand forms and the sound it makes.

@Jeff_Parish yes i could do that through cura but how do i know if the temp is right?

What is your room temperature? Oh wait…it is PLA, so drafts is not a problem.
The PTFE liner should not be soft at 175, so I do not think that is it.
You have a nice metal set of cooling fins, so the top should be cooled nicely.
Stuff squishing out of the sides of a PTFE liner should probably be a cumulative problem.

Does your cooling fan duct left the air hit the heated block? That would be bad and would be worse as height increases because it is picking up less hot air from the heated bed assuming it is heated.

@NathanielStenzel no it doesnt its actually quite far from heater block

I had a similar problem that turned out to be overheating stepper driver chip… but that was causing audible step skips…

Temp too low or under extrusion. Check drive gear for slippage on the filament and as long as your oozing is manageable, bring those temps up.

@Matthew_Del_Rosso I don’t know if this will help your problem but here is the answer to your question.

Position your nozzle about 3-4" above your bed. Start extruding a strand and watch its behavior.

If the temp is too cold it will pig tail at the nozzle and never drop down into a steady strand. Too cold can result in under extrusion results.

If it is too cold you might also hear a chipping or grinding on the filament drive gear. This will require you to check the hobbed gear to make sure no chip is built up in the teeth. That will cause an under extrusion symptom as well and the filament will come out very slowly if the gear is clogged up.

Too hot and it will stretch and make a spider web strand. It will not be able to holds its own weight.

Just right and it will make a straight strand that descends quickly and coils like a rope on the bed. Stop extruding and it will stay there making what I call a “Cobra”. The strand should measure around .48 mm +/- 0.02mm in diameter for a 0.40mm nozzle.

Typically for good PLA I see temps of 190 - 110.

If you get up to 225 and the filament is still not flowing properly there is a very good chance that something else is wrong. Being apparently heat over time related I would suspect your PTFE tube.

Once I have a good flowing temperature I then calibrate my filament to eliminate under or over extrusion. My flowing temperature will be with in +/- 5C of a good calibration temp that balances the physical diameter with the thermal properties. I made and use the following object to calibrate my filament. http://www.thingiverse.com/thing:1037301

All this just provides parameters to eliminate your filament temperature and possibly quality (sometimes there are bad spots) as a cause for the under extrusion. After this start looking and the mechanical parts of the printer. I think yours is time related if it is about the same place each time. However, there are hints of under extrusion almost at the bottom layers from what I can see in the pictures.

If you have ever had inefficient cooling at higher head temperatures you could have cooked your PTFE tube and then even at lower temperatures after enough time has passed in a hot environment it will swell and clog up your flow resulting in an under extrusion symptom. This will get progressively worse as time goes on. If the PTFE tube looks slightly tan or brown on the end then replace it.

@Jeff_Parish thanks for the reply! I checked my PTFE tube and looks perfect like the day it went in which makes sense as ive never printed above 200 with it. I’m doing so teat prints now and calibrating my filament temp like u said, ill update you on the outcome.

Good, PTFE is fine. Curious as to the results of the filament calibration as we are quickly eliminating all the typical causes for this. Still seems to me to be time and temp related…

Any weird noises coming from the printer during the print?

@Jeff_Parish yes i actually was hereing an odd noise about halve way through. it was a sort of click noise. but as i was hereing alot of other noises comeing from the printer i thought nothing of it.

@Jeff_Parish ​ also during the calibration i found that 185 seemed to be the best, though i still saw a little stringing but a 175 it was bunching up and the hotend opening

Try bumping up the flow ratio a tad bit or calibrate your E-steps?
Did you check your stepper current setting? What controller do you use? Pololu stepper drivers or other?
I think stepper motors make a clucking noise when they skip steps. It is the best description I can make.
If you do have skipped steps, you might have filament grinding issues after you resolve the skipped step issue.

@NathanielStenzel well i have a printrbot simple metal, so whatever comes with that i have (honestly i know nothing of circuits). i dont see it skipping steps though. as for stepper current i left it on the defult setting i have no idea wgat ut us though