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Voron 2.4 Clockwork 2 extruder not functioning properly (after hundreds of successful prints)


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I'm sure there's a simple answer here but my extruder is starting to fail and I was hoping to get some guidance. Here are the details:

1) started with the FormBot kit which I think includes the "BMG extruder kit"

2) It has metal gears and has served me well for hundreds of hours of printing.

3) Recently it started to fail - just testing extrusions it will work a little and then the filament stops flowing, then it might start up again.

Seems to me like it's got gripping problems now. The arm that locks in place no longer feels "stiff-ish" when locking it down, even after turning the knurl knob almost all the way.

I took it apart and cleaned it but that didn't seem to help.

Is there a "general" recommended kit or something I should use to rebuild the pertinent parts? Unfortunately I might be in a small jam if this needs any new printed parts, although I have a small Kingroon KPS3 that works well and I've printed ABS parts on before that I could use in a pinch.

Also, when using Klipperscreen to extrude, when selecting speed 10 (or whatever the next speed up from 5 is) and feeding 25mm it works almost every time. But when I select "load" which feeds a lot more at a much higher rate it'll feed for a bit but then stop feeding and click every now and then.

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2 hours ago, DennisM said:

'm sure there's a simple answer here but my extruder is starting to fail and I was hoping to get some guidance

A few things to check:

1. The spool of filament does not have a twist in it, and gets caught when pulled by the extruder. (Happened to me last week - a print would fail about 10min into the print). As you, I took the extruder apart and rebuild it before noticing this.

2. The reverse bowden tube is still allowing free movement. The heat can affect the cheaper "PTFE" tube and cause increased friction. It may have kinked at some point, etc. Replace it if you have some spare.

3. You haven't got a partial clog in the nozzle. Do a "cold pull".

4. The anti-squish screw has not come loose (Should be eliminated as you did a rebuild)

5. The motor wires aren't "fractured" or has a loose connection

6. The small bearings in the plastic parts of the extruder have not moved, putting the gears out of alignment.

Maybe there are other things that can causes this - someone may elaborate.

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3 hours ago, DennisM said:

Seems to me like it's got gripping problems now.

Since we are 'Voron users', it directly means we are also Voron builders. Thus we know how our machinery works. If we can build a Voron, even when we did not source it ourselves, we know the hardware and the electronics in our machine.
Even though the Voron team compares the Vorons to a rocket, I do not think it is rocket science 🙂

You have to systematically check everything like @mvdveer lists. It looks like a list a detective would make, or a doctor. Make a list of hypothesis and see if one is true or false.

If you are not patient enough, you can (and I think should) find the solution by looking very well at your problem. 

a- Your problem seems to be a 'gripping' problem: the thumb screw doesn't feel tight at the end.

b- When you extrude with more than 5mm/s, your extruder dysfunctions, with skipping of the stepper. 


1- As @mvdveer writes above, your sometimes-working extruder problems can be caused by a partial clog. Follow his directions to solve a partial clog problem. Test and if that did not solve the problem...

2- the problem you describe can be caused by a dysfunctional motor. I understand from manufacturers all these motors are made for high temperature, so they do not burn with 50-60 chamber temps. But the wiring can be broke. If you have an extra pancake motor, replace it with that and see if that fixes the problem.

3- it is possible that the extruder parts inside the CW-2, have loosened somehow. Disassemble your CW-2.
Check the fixation locations. Check SB manual CW-2 assembly from page 10 on: are all heatset inserts still in their locations?
page 17: is the BMG Idler fixated to the ABS arm?
page 19,20: are all the bearings still there? The screws? 
page 21: are the gears all fixated? the set screws still there? 
There is a reason they mention 'thread-locker' on every page 🙂

If everything checked out okay, start assembling the CW-2 again.
page 23,24: make sure the alignment of the filament path is correct.
page 25,26,26,27: check that the gears lock / interlock, the tension knob works as intended. Before you add the motor, all should fit flawlessly. The gears should turn when all is locked up. 
page 28,30: add the motor. and adjust your screws exactly as described in the manual on page 30.

If until now everything was okay, I think there is a problem that is not caused by your Clockwork. I would consider rebuilding another CW2 with new material 🙂


3 hours ago, DennisM said:

"general" recommended kit

As stated in the SB manual, it is just simply Bondtech BMG gears. Here is one on aliexpress and costs 3.5 euros for me. With it you could build a new CW-2 by printing the ABS parts. First make sure though, that your pancake motor is functional.

If you do not want to bother with all this CW-2, you can consider purchasing a Galileo / Orbiter 2.0 / Orbiter 1.5  extruder from all known resellers. 


I hope this  helps

Edited by Dirk
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I'm just going to chime in and say...

Stuff wears out.

My CW1 and CW2 extruders wore out after hundreds of prints and, I'm guessing yours has suffered the same fate or more accurately... one or more components of the extruder have worn out.

In the end... None of my 4 printers has a 3D printed extruder anymore, (except for the CW2 in the Switchwire I built but, that's been given to my nephew so his problem now 😄 ). My 2.4 and both RatRigs have LGX-Lites and my VzBoT has a CNC aluminum Hextrudort. I know, I know... the LGX Lites are 3D printed LOL. They're SLS and much tougher and more stable than FDM printed extruders.

I would also recommend getting a new "precision" 50T extruder gear. There's been a number of complaints about extruder gears (especially the cheapo ones that come with Formbot kits) that have a considerable amount of runout. $12 well spent, IMO, if you're going to rebuild your CW2.


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well you aren't alone.

My OG 2.4 was having issues and I went down the rabbit hole from replacing hotend (I have spares), nozzles, rebuilding CW2 a few times including changing out the BMG for real Bontech edition, new printed parts, all the fun.

My solution, so far, was galileo 2 and back to my OG hotend and nozzle and all issues are gone.

I really put in a lot of effort to try and find the problem - from that silly FHCS screw that *loves* to come loose and move, to cheap and not cheap BMG parts, and even had a friend print me the CW2 parts so I could rule out my other printers.

Like someone said: things wear out and I'm in the boat that it is time to replace all of my CW2 as 2 other machines are now showing the exact same problem even though the ages are vastly different, number of hours comparable to my first Voron (Trident 300, which, is now showing the same issue after almost 2k hours).

Could be bad printing (all on me, baby, no one else to blame), could be bad parts (yep, same thing, on me), could be I just don't know what I am doing (and that would be the #1 thing).

tl;dr: I started having issues with a 2.4 and CW2 and ended up replacing it with Galileo 2, and now my other Voron units using CW2 are showing the same problem.

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OK, hold the boat! What's Galileo 2 ?? This looks exciting and I'm OK with changing the whole toolhead out if CW2 generally has issues. Also, I was in the process of building a Stealthburner but maybe do folks recommend I build a G2 instead?

Looks interesting...

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Um, sorry for sounding a bit daft there - the G2 is a replacement for the CW2 extruder it looks like and is a drop in replacement for what I have now.

So I can hopefully keep the existing afterburner toolhead (AB-BD version is what I am using) and install just the G2 extruder part.

I think that's how it works...

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@DennisM It all depends on how deep you want to dive... I had an OG CW1 and Afterburner in my 2.4. Then I went with Afterburner hotend / shroud and front cover with my old CW1 for a while. I had the OG probe, then klicky and now I have SB with LGX-Lite, Rapido and OG TAP. So far the LGX-LIte and Rapido were good choices. They work 100% of the time and are solid performers. They're reliable and predictable. You also only need to print the SB adapter for the LGX-Lite (one part). The LGX-Lite goes for ~$70 USD.

With that said... You could go or Galileo 2. You need, 5-6 printed parts, custom shaft, gears, motor, etc for around the same price as the LGX-Lite.

Here's how the LGX-Lite integrates with a Stealthburner.

In grey is the LGX-Lite with adapter and cover.




On the printer



It's a super clean install.


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I just experienced this same issue with my V2.4 with hundreds of hours of printing on it. All the maintenance had been done routinely, yet it was still doing what seemed like either an extruder failure or nozzle clogging. The fix for me was replacing the hot end fan. The GDS time fan finally was not pushing enough air, I changed it for a Noctua fan and it is back working as it has since it was built.

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This is one of the really nice parts of the Stealthburner design. It's modular. Add Tap? Just swap out the carriage mount bits (ok that one's a bit of work). Want a different extruder? Just swap in one with compatible mount points.

I just swapped my trusty old CW2 with a Galileo 2 and am liking it so far. It was literally plug-and-play. With the couple of tweaks to the printer.cfg file to account for the tuning differences.

Way back when I built the Trident I used some clone gears that gave me issues. I swapped to proper, good Bondtech gears, and those have been in use for a couple of years and thousands of hours of printing.

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Yeah, Thanks a lot @claudermilk... Now I'm thinking about trying a new extruder and Oh yeah, and I also started thinking about the new Rapido 2 hotend as well.

See... that's what happens when you hang around places like this.   😄😆😀

All kidding aside,

Agree, and budget kit companies will source budget components. From the outside everything looks the same but later on, after you've used it for a while, the flaws reveal themselves. Now I'm not complaining... things wearing out on my printer adds another layer to the experience of going beyond ownership to being a legit builder. So, now I don't build new, I rebuild to enhance.

One of the really nice things about this hobby.

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Going though this issue on one of my Tridents right now. Don't know what going on but just wont grip the filament enough. Solving this issue by just going to the LGXLite im using on several others. I really should figure out what the issues is but just no time... I've got to the point of having too many printers to be messing around all the time 🙂


Edited by Nurgelrot
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OK, lots of interesting things here to read 🙂

So I'm most likely going with the Galileo 2 option but now I'm curious about the LGXLite. So is it basically something like this:


And then with some printed adapter/cover parts to make it work on the 2.4 Voron?



I think maybe so .. I saw this :https://www.printables.com/model/466794-voron-24-lgx-lite-extruder-mod

Edited by DennisM
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@DennisM if you use the PCB pay close attention to the notes on the PCB mounting for that SB LGX mod. Getting the 2 pieces PCB to line is up is trickey even with the alternate front board they list on printables. You may want to go with the SB2040 toolboard modded lgx-SB even if you dont actually use the sb2040. That mod makes the right side of the SB bludge out a bit and has more room for the PCB/Toolboard. Not as ascetically pleasing as the stock SB but it works. 

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I have tried both the LGX Lite and Galileo 2 on the Stealthburner in my V2.4

I like them both. 

I really like the LGX Lite but the toolboard mounting is very poor and I'm not a fan of the modified Stealthburner front needed to accommodate this.  My favorite feature is the filament release lever.... just "click" and out comes the filament. The LGX lite does not have a spring-loaded idler (driven or not) pushing into the filament. It instead uses a fixed spacing between the two driven gears. This could cause issues with filaments of non-standard diameter but was never an issue for me. 

The Galileo2 is a very good extruder with a unique 9 tooth sun gear in its planetary set, so it needs a specific motor.  Unlike most modern extruders, on the Stealthhburner version it reverts to a non-driven plain idler which is fixed, and the motor / drive gear pivots instead, with a conventional spring pressing it into the filament.  This seems to work well but holding the motor back against spring pressure to release the filament is a pain, as with most conventional extruders with a spring-loaded idler.  

The Galileo 2 can alternately be built as a drop-in replacement for the Orbiter 2, which I'm using on the Voron 0.2 .  This has a convenient knob on the driven shaft which makes loading and unloading filament a breeze. 


PS- I looked at the LGX Stealthburner link you provided, it is a newer version than the one I tried. It mounts the toolboard much differently and hopefully better. 

Edited by ChicagoKeri
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@ChicagoKeri Thanks for the excellent advice based on your experience. I never thought about something as simple as the release tab/lever being an issue between the different models. I have another printer that uses a strong spring pressing the rollers together and to load filament there it requires significant pressure on a lever to keep them apart while loading, which isn't very comfortable. Also that one is a Boden model so it requires feeding a lot more than a direct drive.

I appreciate the feedback from everyone and you've given me a bunch of things to consider.

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  • 2 weeks later...

To the original question-  you did check the guidler bolt is in place? Mine repeatedly displaced itself after a short while into printing and it gave me inconsistent flow. I glued that bolt back into its  place on the snap- in brackets of the colored guidler arm and now my CW2 works flawlessly again. 

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Thanks to everyone who replied here and expanded the original question into an interesting discussion about the various extruder options for the Voron printers.

I thought I had mentioned this, but just to clarify I fixed my problem by simply replacing the nozzle, which was clogged. After heating up the nozzle, I unscrewed it and then used my 0.4mm metal rod to clear out the excess filament and other gunk in the path of the filament.

Once that was clear, I installed a new Micro Swiss nozzle and things were good to go after that.

I actually have never done a cold pull myself but the process above worked for me.

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