Extruder Gone Bad

[claudermilk]

I got the printer working nicely, sent a print job last night that looks like it completed ok. Tried to start another job this morning, and now the extruder won't extrude during a print job. I took a shot video where you can hear the horrible grinding it now makes. No filament extruded, just grinding. I can push the filament by hand (that's the gloopy mess on the plate). I can tell it to extrude via the web interface no problem. I've poked the nozzle out--no clog at all. I have disassembled the darn thing three times now and nothing looks amiss. The grub screw is tight, everything spins ok. The most it did was get the hobbed screw parts aligned perfectly. I'm at a loss what the heck is going on here.

 

 

 

[ken226]

Does the extruder motor shaft rotate?   Perhaps the motor could have seized or a grear in the extruder stripped?

 

If the motor rotates freely and there are no gears stripped, perhaps the stepper motor driver is bad?   

 

I havn't experienced it on my 3D printer, but on my CNC mill i've had a bad GeckoDrive motor driver cause a sound something like gears grinding, as the motor shaft just vibrates.

Edited May 2, 2023 by ken226

[claudermilk]

Yep, the motor spins. I dismounted it and ran it hanging loose, spins just fine. I've disassembled the CW2 again and carefully reassembled it. I cannot see anything that looks amiss, everything spins freely. If I just issue an extrude or retract command from the web interface it happily does it. I've changed filament, and tried three different nozzles--no clogs. It is only when I try to actually print that it freaks out. I've done live Z adjustment and had it print in air just to eliminate the possibility that it's too close, no change in behavior.

Here's a second video in which I'm running my filament load macro. Note there is no filament, so it's just running. WTF is the problem? I have no clue now, except maybe somehow a bad motor that spins with nothing attached.

 

 

 

[atrushing]

37 minutes ago, claudermilk said:

If I just issue an extrude or retract command from the web interface it happily does it. I've changed filament, and tried three different nozzles--no clogs. It is only when I try to actually print that it freaks out.

This sounds like it could be a loose wire connection. When everything is still the connection works reasonably but when things get moving then the connection becomes intermittent and the motor exhibits epilepsy..

[Penatr8tor]

I think @atrushing 's deduction makes the most sense to me.

@claudermilk... Can you jiggle or move wires while it's extruding to see if the motor stops?

 

On a side note and not related but... I had a terrible time getting my Z endstop sorted when I first setup my 2.4. I couldn't for the life of me figure out why the Z offset kept changing every two or three prints. After much fussy around I decided to yank on the safe Z endstop and wouldn't ya know... I had forgot to tighten the mounting screws. I mean, I thought I had 100% tightened everything LOL.

Hope it's just a loose wire. 

[ken226]

Thats odd.

Just spitballing random ideas here, but  any change that your Z height?  I had something like that once, when the nozzle was so close that no filament could extrude out.  The build plate was completely obstructing the nozzle, but not quite enough to be scratching the plate.  

Edit:  Nevermind.  I see that you already checked that.

Edited May 3, 2023 by ken226

[mvdveer]

I would tend to agree with wiring being the issue - A break in the cable chain somewhere? 

[leo etchaas]

I have kind of the same problem it is so annoying

[leo etchaas]

maybe try printing PLA because for me PLA works but ABS does not.

[Penatr8tor]

@mvdveer Nice photo!!! 

[Flob74]

I encountered severals jamming issues and now it's working for me and I learned a lot of good tips.

1- Ensure that the mechanic is correct. 3D plastic parts are not cracked, or melted. Screws are tighten and the extruder kit well mounted and free to move with the motor.

2- Set correctly the extruder tension (between the two teethed gears). Not enough and the tooth won't grip the filament. Too much and the toothed gears will gnaw the filament and won't grip.

3- Ensure that the extruder's motor is wired correctly. If a wire is disconnected or inverted, the motor won't offer all his power.

4- Check the stepper current in printer's config. If it's too low, the motor won't deliver enought power, and too high the motor will overheat. It depends of your motor's characteristics (check the datasheet of available).

5- Ensure that the heatsink is properly cooled. Otherwise, the filament will melt in the heatbread and create a jam. I use a high flow dragon hotend which offers a small heatsink surface. Some a modded specific stealthburner's airduct exist to increase the airflow speed. I also replaced the sunon fan from my Voron kit for a gdstime fan which is supposed to have more airflow. If it work with PLA but not with ABS, maybe it's a temperature/cooling problem.

6- Ensure that the retraction lenght is minimized. Otherwise, the melted filament will be pulled in the heatsink -> same problem as point 5.

7- Maybe your ABS is wet. A wet ABS spool can ruin your settings, increase the melting temperature of your filament and stuck it in the hotend. Don't trust the melting temperature provided by the filament's seller. It depends on your thermistance's precision, the moisture of the filament, etc...

8- Maybe you buy a filament with many diameters defaults (cheap filament). Sometimes it's ok with 1.75mm and sometimes it's stuck because the diameter measure 1.50mm and this ruin the tooth gear pressure at point 2.

9- Don't turn of your printer without a proper cooling of your hotend with filament inside (always wait below 50°C). The cooling fan could turn off, the heat will spread in the hotend, melt the filament inside and will cause a jam the next time you turn on the printer.

 

It's not perfert nor exhaustive, but I hope it will help someone.

Edited May 4, 2023 by Flob74

[claudermilk]

Thanks for the extensive rundown of things to look at. Sadly, this is a formerly functioning extruder, with known good PLA filament at the moment.

So to a bit more troubleshooting spurred by @mvdveer and @Penatr8tor. I pulled the motor wire a bit loose and wiggled it around while doing an extrude command. Sure enough, it started making some of that nasty grinding noise. It seems perhaps there's a wiring issue. I'll have to build a patch cable to eliminate the cable chain run and see if that clears anything up. I suspect that might be it--the wires have a LOT of hours on them. It might be time to bite the bullet and rewire the printer with the hartk 2-piece tool head PCB, LDO breakout PCB, and Linneo harness I have waiting. 

[mvdveer]

7 hours ago, claudermilk said:

printer with the hartk 2-piece tool head PCB, LDO breakout PCB, and Linneo harness I have waiting

Canbus? Be brave....

[Penatr8tor]

55 minutes ago, mvdveer said:

Canbus? Be brave....

Was thinking the same. Why not?

 

 

 

 

 

 

 

 

I'm sure there are plenty of reasons LOL.

[claudermilk]

[claudermilk]

I had a full weekend, but I was able to carve out a couple of hours to start tackling this. I need to rename the thread to "WIRES Gone Bad" because after 1700 hours of use, even PTFE wires wear out. The issue turns out to be a worn-out, broked extruder motor wire within the X cable chain.

The culprit:

 

What the inside of a cable chain looks like after 1700 hours:

 That's some wear.

So now the printer is torn apart with the wiring halfway replaced. I'm "upgrading" to a 2-piece hartk toolhead PCB now that I have to tackle rewiring. More on that in my build/upgrade diary.

[Penatr8tor]

@claudermilk Well, I'm glad you found the issue.  I think it's a wise decision to upgrade while you're at it.

I'll be following along. 

[mvdveer]

6 hours ago, claudermilk said:

I'm "upgrading" to a 2-piece hartk toolhead PCB

Good upgrade, though will it solve the breaking wires in the cable chain? I know a Canbus will!  Just winding you up

[claudermilk]

Insert flip off GIF here.  It's people like you wot cause unrest.

Yeah, after another 1700 hours or so I'll probably have to unplug the 14-pin harness, buy a new one, and plug it in. I also don't want to mess with the added height umbilical will add and I just prefer the clean routing on the cable chain.

Honestly I had suspected this was coming for a while, I was just a bit slow on the uptake that broken wire day had finally arrived. I've been waiting for an excuse to rewire with the toolhead PCB, and now I have it.

[mvdveer]

The PCB works well - I have this on the first V2.4 I build over a year ago - in a cable chain and fingers crossed - still going strong. Love the fact that you can remove the SB face without having to unplug a multitude of wires. 

[claudermilk]

Yes the breakout board is nice. Update in my build thread.