Extrusion Problem  

Re: Extrusion Problem

What temp are you printing with?

Have you tried printing a "column" raising temp from for example 180 degrees to 230 degrees with 5-10 degrees increments? Then you can probably see if it skips at lower temps for example, and at what temp it prints well.

Have you checked the tension on the idler screws?

your boat to the right there looks so messy, both under and over extruded at the same time. Could you print the Benchy instead?

Re: Extrusion Problem

Could this be due to to faulty filament with varying thickness?

Re: Extrusion Problem

I had a similar problem yesterday, printing Taulman T-Glase.

I designed a LED holder for the printer enclosure, and when I printed it for the first time, there was a gap between layers where the print could very easily be pulled apart. I decided to just print it again and to observe carefully during that particular level of printing.
I used the same .gcode file, just started print again, and it printed very well.

I wondered if it could be a loose belt, but that makes no sense because the z-axis does not have a belt.

Could the z-axis motors be loosing count and then somehow print one particular layer a bit too high up, so it does not properly attach?

Re: Extrusion Problem

What temp are you printing with?

Have you tried printing a "column" raising temp from for example 180 degrees to 230 degrees with 5-10 degrees increments? Then you can probably see if it skips at lower temps for example, and at what temp it prints well.
Temp should not be an issue, I am having this problem with the Prusa compiled gcode that came on the SDcard while printing with the filament shipped with the printer directly from PR.

Have you checked the tension on the idler screws?

Idler screws are properly tensioned at 13mm for PLA

your boat to the right there looks so messy, both under and over extruded at the same time. Could you print the Benchy instead?
I actually have printed a Benchy. That has been my only successful print since this started happening, but it still has very uneven layers compared to other benchy's from before. I'll share photos when I can.

Could this be due to to faulty filament with varying thickness?
My filament shouldn't be faulty, I've had successful prints with it before, and like I mentioned in response to Patrik, it is PR supplied filament.

Re: Extrusion Problem

Your filament is suspect, Try changing to another. Was it kept dry? How long between prints with your Prusa Research filament. And in its box with silica gell bag? I went away on holiday for a week and my Prusa Research filament was a pain to print when I got back. It was left on the spool and open to my printer rooms environment with the door open. Try Rigid.ink my favourite filaments. I have printed with many of them, and get great prints.

Re: Extrusion Problem

I live in the desert. It was probably a difference of two days between printing an enormous filigree skull that printed perfectly and then having this issue. I have more PLA filament being delivered today so I can try that, but I'm doubtful the filament is the issue.

Re: Extrusion Problem

I'm still having this same issue. Since the last time I've posted I have:

* Used brand new filament
* Replaced the brass nozzle
* Replaced the thermistor and thermistor wiring
* Added an E3D sock
* Rebuilt the hotend

Here's my latest print:

Re: Extrusion Problem

Looks much like my problem, see http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/layers-missing-in-benchy-t2208.html#p17464

I think in my case it was due to me using the wrong material to print replacement parts for the extruder cover, body and idler.

Taulman T-Glase gets too soft and starts to bend when it gets warm, then the pressure on the extruder idler pulley reduces until it starts to slip. That causes weak layers. If it gets too bad in one spot, then a notch gets ground into the filament and it does not move any longer with the rotation of the extruder notched pulley. Then the printer continues to pring in mid-air without any filament being extruded, until it thinks it's finished.

However, I'm yet to prove my theory by printing another benchy, now that I have reprinted all relevant parts from Polycarbonate, replaced the fan I broke while tinkering, and replaced the nozzle with a hardened steel nozzle.

Check if the extruder idler screws are tightened appropriately, maybe tighten them a bit more.

Re: Extrusion Problem

Looks much like my problem, see http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/layers-missing-in-benchy-t2208.html#p17464

I think in my case it was due to me using the wrong material to print replacement parts for the extruder cover, body and idler.

Taulman T-Glase gets too soft and starts to bend when it gets warm, then the pressure on the extruder idler pulley reduces until it starts to slip. That causes weak layers. If it gets too bad in one spot, then a notch gets ground into the filament and it does not move any longer with the rotation of the extruder notched pulley. Then the printer continues to pring in mid-air without any filament being extruded, until it thinks it's finished.

However, I'm yet to prove my theory by printing another benchy, now that I have reprinted all relevant parts from Polycarbonate, replaced the fan I broke while tinkering, and replaced the nozzle with a hardened steel nozzle.

Check if the extruder idler screws are tightened appropriately, maybe tighten them a bit more.

Thanks for your input! All of my parts with the exception of the spool holder are stock, I've only had the printer for two weeks. I used a digital caliper to properly tension my springs to 13mm, so that shouldn't be the case. I'm pretty sure the stepper motor is slipping when this happens, not the filament.

The only thing I can think of is putting thermal compound between the threads of the heat break and heat sink, which would require another disassembly of the extruder head.

Re: Extrusion Problem

I would just tighten the screw a bit more, to something like 12mm, and see what happens.

Maybe the springs in your printer are a little bit weaker than average and need to be tightened a little more to achieve the right pressure.

Re: Extrusion Problem

I may have tried running them tighter at one point, but I can't be sure. Regardless I just took apart the hotend again, looks like thermal compound is already where it needs to be, I'll probably reapply and see if that does anything. I've taken my hotend apart so much now the 3d printed pieces are starting to fail... And my heat block is a mess from all these failed prints. :/

Update: Brass nozzle just broke off in my heater block with little to no effort.

Re: Extrusion Problem

Sorry to hear about your nozzle, that could be tricky to get the rest out of a hot hotend.

How do you think a hot-end problem causes your layer failures?

What problem are you trying to solve by taking the hotend apart?

Re: Extrusion Problem

Considering that you need a new nozzle, I would get a hardened steel one.

I just installed one, and then caused some clogging by experimenting and swapping between polycarbonate and PLA filaments. I think either some PC remained in there because it was no longer hot enough for it when printing PLA, or some PLA got burned to a crisp when using the PC.
Long story short, I figured that I could just print something from carbon-fibre laced filament, now that I have the hardened nozzle. If it abrades the nozzle so soon, then it should clean out a hardened nozzle nicely. So I printed a 50mm x 5mm diameter tube from XT-CF20, and once it was finished, I immediately turned on pre-heat and then unload filament + reload PLA filament. Then, repeatedly start "Load filament' to push high flow PLA through the extruder while still at 250degC, then reduce extruder temp to 210degC while continuously extruding PLA. It seems to have worked, nozzle cleaned out and printing nicely again.

Now I have Benchy printing again to see if my missing layers problem is really fixed or if I am just unrealistically optimistic..... 😉

Re: Extrusion Problem

Sorry to hear about your nozzle, that could be tricky to get the rest out of a hot hotend.

How do you think a hot-end problem causes your layer failures?

What problem are you trying to solve by taking the hotend apart?

My logic is that if the symptom is my filament jamming, then the issue must be within the hotend. I don't know what it could be, but I have to disassemble it to get the broken nozzle out anyway. I might have to set a timelapse up the next time I print so I can watch temps and see what's happening when the hotend begins underextruding. I already know that the extruder stepper will skip and not be able to push any filament through, but I don't know what the run up to that is. Even more so I have no idea why it would go back to printing fine during the same print, I just wish I had the time to watch a print all the way through. 🙁

Re: Extrusion Problem

Sorry to hear about your nozzle, that could be tricky to get the rest out of a hot hotend.

How do you think a hot-end problem causes your layer failures?

What problem are you trying to solve by taking the hotend apart?

My logic is that if the symptom is my filament jamming, then the issue must be within the hotend. I don't know what it could be, but I have to disassemble it to get the broken nozzle out anyway. I might have to set a timelapse up the next time I print so I can watch temps and see what's happening when the hotend begins underextruding. I already know that the extruder stepper will skip and not be able to push any filament through, but I don't know what the run up to that is. Even more so I have no idea why it would go back to printing fine during the same print, I just wish I had the time to watch a print all the way through. 🙁
I was just about to suggest just that: Watch it.

I have started to call my printer "My Prrrrrintiousssss" lately.........I spend way too much time on my knees offering it service. Slave to the machine.

But every now and then I stick a spanner into the fan, and then Printious pretends that I'm the master for a little while... 😀

Re: Extrusion Problem

We'll see. I finally got a response from someone at PR last night, hopefully troubleshooting with them will set me off in the right direction. I appreciate your help Michael.

Re: Extrusion Problem

I managed to print Benchy without layer problems.

But it looks more like the "Flying Dutchman" ghost ship with all the spider webs! 😀

This was using SLIC3R_Settings
0.10mm DETAIL
PRUSA PLA 1.75mm-EMult1.053
Original PRUSA i3 MK2 with ZHop

So then I tried again with SLIC3R_Settings
0.10mm_DETAIL_Quality_Brim
PRUSA PLA 1.75mm-EMult1.053
Original_Prusa _i3MK2_ZHop_5-120

and then with Z-Hop 5-100. Both failed, printing the invisible type of ghost ship, cause by the filament being ground away into a notch until the extruder stepper does not move it any longer. I'll try again with progressively slower retraction speed until it grips.
I think the problem is made worse on my printer because I run the filament through a teflon tube to protect it from moisture. That introduces extra friction, particularly during fast retractions.

Re: Extrusion Problem

It looks good, except for the intense stringing of course. I've got a screw extraction kit waiting for me at home, so I'm crossing my fingers that once I get the broken nozzle out I can clear out the entire hotend and give it another whirl. I want to get printing well so badly so I can start designing my own parts. 🙁

Re: Extrusion Problem

Ok, I rebuilt everything, and now my problem is actually predictable. So now I can really troubleshoot it. This underextrusion seems to only be more prominent when there isn't a large surface area on a layer. If there is a lot of movement and not a lot of printing, the printer will jam up and underextrude. For the benchy this happens when the windows start printing. I imagine if I was executing a similar print with multiple pillars I would get a similar effect.

This must be a temperature problem, but what I can't understand is the reported temperature during the print is not dropping more than 1 degree below the set temperature. What is going on here? I'm kind of lost to what the cause might be?

EDIT: This is in-line with a print from a couple of days ago when I thought I had fixed it. The adalinda print went exceedingly well until the very tip of the wings and the snout, at which point the printer began underextruding.