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golddustpeak
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After between 100 and 200 hours of satisfactory prints with my Voron 2.4r1 I'm having a problem.

I thought it might be attributed to  under extrusion but I've run several CM of cleaning filament through the printer to no avail.

What am I missing or where do I turn for help?00261.thumb.jpg.66bacc9025c36dbd22cf145009764e9a.jpg

TNX

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1 hour ago, SVDB said:

Does it always happen at approximately the same height?

If so, you may have debris stuck on a belt causing it to jump.

No the height of the fault changes from print to print.

My last print separated horizontally  when I removed it from the build plate.:-(

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Hate to say this but it might be time to strip your hotend down and check the components in that. I had a similar issue, random under extrusion appearing. When I stripped hotend down (as everything else had failed to resolve) I found there was a small crack in the guidler which was causing inconsistent pressure to be applied to the filament which in turn was exhibiting as underextrusion.Granted your prints don't look like lace work so perhaps it's a very small bit of wear/damage within the print head, but if you've eliminated all the other suspects (e.g. blocked nozzle, inconsistent filament) and there's not a regular pattern (e.g. something on the belts, other mechanical fault) then that,to my mind, leaves the hotend and a mechanical fault/wear'n'tear in there.

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Update:

I reloaded my original filament I used for calibration and attempted to extrude 100mm..... Between 50mm and 75mm of the filament was extruded beginning with a 25mm extrusion about 4 times the final thin diameter.

I could not significantly change the extruded amount with an adjustment of the idler tension.

I'm hesitant to start messing with the config file as I'm not understanding how it could have changed.

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That's a good diagnostic step. It wont be a configuration setting (especially as it does not appear to be consistent from your description)so your hunch not to muck about with settings is a good one. I'd definitely say it was a physical issue within the head (you have got almost 200 hours on it). If something is cracked or worn then increasing the idler tension with the screw (as one normally would) won't necessarily make a blind bit of difference (granted it depends on where the damage is).

As to "how" then the answer is "bad things happen". Printers are imperfect machines (or fancy hot-glue guns as VoronDesign describe them) with moving parts and that just equates to wear/breakages and therefore changes in performance (sometimes very extreme changes in performance).

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10 minutes ago, smirk said:

That's a good diagnostic step. It wont be a configuration setting (especially as it does not appear to be consistent from your description)so your hunch not to muck about with settings is a good one. I'd definitely say it was a physical issue within the head (you have got almost 200 hours on it). If something is cracked or worn then increasing the idler tension with the screw (as one normally would) won't necessarily make a blind bit of difference (granted it depends on where the damage is).

As to "how" then the answer is "bad things happen". Printers are imperfect machines (or fancy hot-glue guns as VoronDesign describe them) with moving parts and that just equates to wear/breakages and therefore changes in performance (sometimes very extreme changes in performance).

So am I to assume that the next step may be a new nozzle for my Dragon hot end?

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I suppose a question I should've asked was "Was the extruder making clicking sounds?" If the nozzle was partially blocking things then I might expect the extruder to start missing steps/clicking especially as you were increasing the tension on the filament. Now if it was clicking then that's not 100% the nozzle's fault (there could be a blockage in the small PTFE tube for example). If the nozzle was simply worn (as opposed to being partially blocked) then the extrusions/printing would be messy and inaccurate since the nozzle is no longer a nice round 0.4mm.

It's probably a quick sensible diagnostic if you happen to have a spare nozzle on hand (and hopefully cheap, unless you've got tungsten ruby nozzles). My gut is not saying "nozzle" given the significant variation in your extrusion test, that strikes me as driving force.

If a nozzle change makes no difference to that extrusion test you've just performed then I would say the next step is to fully strip the hotend/extruder checking for wear, cracks, damage (especially in the 3d printed parts). Sometimes the damage is not obvious to the naked eye until you try and [gently] flex something and then the crack opens up.

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No spare nozzles on hand. Remember I did run several cm of cleaning filament through it with no change.  The several mm of fatter melted filament is nothing I remember seeing before, I even saw one extrusion where it went fat, skinny, fat then skinny to finish..

I suppose that ordering and having a spare nozzle or two on hand is not a bad idea as sooner or later I'll need one anyway.

As the filament seems top load easily I'm not thinking about blockages.

I'm just dragging my feet on a tear down of the assembly (being the lazy one that I am).

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Yup, I'm lazy too, and the thought of having to strip the extruder is a royal PITA but sometimes these things become unavoidable.

You should always have spare nozzles on hand, my top tip is "Remember where you put them!". When I die and they clear my house they will find god knows how many nozzles (bolts, springs, ICs......) that I've bought and then forgot where I put them beyond "somewhere safe". I suppose my worry might be if something is broken inside the head then do you have spare printed parts or alternate means to produce them?

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Well I finally worked up the ambition to disassemble the extruder and such.

The first thing I noticed was that the PTFE tube was missing (I KNOW I put it in place) with no sign of white plastic in the extruder.

Next in inspecting the parts I discovered that the MR85 bearing outer bearing on the drive gear was trashed.

I cannot see anything that could have caused such but parts are on order and we'll see.....

 

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The missing PTFE tube is really interesting, it had to go somewhere (wonder if the under-pant gnomes are branching out). I doubt the bearing would've been involved in the disappearance of the tube, sadly it's probably just wear and tear (even with a good brand you could've just  "lucked out" and got the outlier).

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I had a similar problem with a completely different cause. My PTFE coming from the spool to the extruder had developed a crimp and caused under-extrusion every time the tool head traveled to a specific section of the bed. It was a bear to figure out... Replacing the PTFE and removing the filament out detector fixed my issue ( after rebuilding the whole tool head and reworking the entire belt system. Doh!)

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  • 3 weeks later...

The parts finally arrived and I installed two new bearings on the drive gear and installed a new PTEF tube.

Its now back to happily printing.

There appeared to be some small missing bearing parts in addition to the PTEF tube but who is to say.....

I'm just happy that it was a fairly easy fix.

Thanks again smirk and all

  • Voron FTW! 1
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