PETG clogs in extruder

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Kryfin
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PETG clogs in extruder

Post by Kryfin » Fri Jun 23, 2017 4:26 am

Hello,

Yesterday I started having issues with my PETG filament getting clogged in the extruder shaft. I have been using Maker Series 1.75 PETG filament for awhile now with zero issues. Now it seems I cannot get the clogging to cease.

I have checked the tension on the extruder wheel, burned out extruder shaft and nozzle several times after getting the clogs, tried another filament from a different manufacturer, checked the extruder gear for bits and pieces with none found. No settings were changed and I print at 260C at 50mm/s. I have nozzles on order but they are not here yet. When I extrude without the nozzle the filament flows nicely. I have checked the opening of the nozzle and I can see thru it but I have run out of ideas. Can anyone help?

Thanks
Matt

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sthone
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Re: PETG clogs in extruder

Post by sthone » Fri Jun 23, 2017 3:38 pm

It sounds like your nozzle is partially clogged still.

When you say you "burned out extruder shaft and nozzle several times" how are you doing this?

The best way to clean out the Barrel (extruder shaft) and Nozzle at the same time (without removing anything from the printer) is to do a cold pull with cleaning filament or nylon a few times.

If you remove the nozzle from the hotend (take the hot end off the printer first!) the most effective way to clean out just the nozzle is with a propane (or map gas) torch. Hold the nozzle with some pliers and heat it with the torch and it will burn everything out. I usually run some cleaning filament through it after that.

-Steve
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Kryfin
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Re: PETG clogs in extruder

Post by Kryfin » Fri Jun 23, 2017 5:39 pm

When I say "burn it out" I mean removing the hot end from the printer and using a propane torch to melt away all of the filament in the shaft and nozzle. I reinstall, level bed, extrude a small amount of filament, try another print and it clogs up within the first layer or two.

When I put a piece of filament down the shaft when cold it feels like it hits a ledge or something inside the shaft about 5mm in the tube. I do get the filament to extrude so I know the filament is past that little ledge but it hangs within a few minutes every time.

Would the multiplier have anything to do with this? It is PETG and I have .35 nozzle and multiplier at 82 with print speed at 50mm/sec.

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ednisley
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Re: PETG clogs in extruder

Post by ednisley » Fri Jun 23, 2017 7:00 pm

Kryfin wrote:Would the multiplier have anything to do with this?
No. However, if you haven't measured the actual filament diameter and set the Extrusion Multiplier correctly by measuring some hollow boxes, then it's probably incorrect and giving you poor results, which can contribute to all manner of mysterious problems.

The appropriate Beginners Guide will tell you how to calibrate everything; they're in the stickied post at the top of the Getting Started forum section.

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sthone
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Re: PETG clogs in extruder

Post by sthone » Fri Jun 23, 2017 7:50 pm

Also if you have seen Jules PETG Thread go read that too. It's probably one of the most informative things on the internet when it comes to starting with PETG.

-Steve
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Kryfin
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Re: PETG clogs in extruder

Post by Kryfin » Sat Jun 24, 2017 5:53 am

OK I have read all the guides including the very nice write-up that Jules shared. I have actually been using most of the settings from Jules write-up for the last 8 months printing solely with MakerGeeks 1.75 PETG with zero issues. Three days ago i had a clogged hotend that I removed and tried to reprint with no luck.

I did replace the nozzle but the problem did not get any better and additionally I used a propane torch on the hotend shaft to remove any stuck filament. I was normally printing at 247C until this issue began with the same spool I had printed about half of already. It appears to me that the hotend shaft is getting clogged about 10mm down after the filament leaves the extruder body. I can retract the filament and it shows no bends and the gear marks look adequate. I simply feed the filament back into the extruder and slowly extrude in 1mm pulses and the filament flows correctly down and out of the nozzle until I start to print. It will usually clog up again in the first 2-3 layers. I have no bed fan on first layer and 100% bed fan after that. I usually run at 50mm/sec but I have tried 40mm/sec with no luck.

I have tried every temperature from 220-295 and the only temp I can get to flow correctly is 295. Is this clogging caused by heat creep, a bad thermistor or hotend heater, or maybe something else. I am out of ideas and I know this filament used to print at 250 and now 295 seems most rediculous.

Thanks for the support,
Matt

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sthone
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Re: PETG clogs in extruder

Post by sthone » Sat Jun 24, 2017 6:18 am

Ok try this first... (to see if it's actually a clog or something else) next time it clogs (stops printing) try extruding some filament manually with the buttons and physically push the filament into the top of the extruder drive to force it through and see if the filament comes out of the nozzle. If it does the problem might be with your extruder drive and not an actual clog. (look for cracks)

If you still can't get any filament out of the nozzle and you tried with a new nozzle there might be some junk still in the barrel.

You either need to do several cold pulls (insta explains it best) or you can even remove the nozzle (remember to remove the hotend from the printer first) heat it up (temp = for what ever filament your running) and try pushing a small allen wrench through the barrel from the top to push out the junk.

-Steve
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Kryfin
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Re: PETG clogs in extruder

Post by Kryfin » Sat Jun 24, 2017 10:40 pm

Just wanted to give a big thank you to Steve for staying with this problem and offering his suggestions. It is appreciated and I am sure someone else may or already has run into this problem.

Turns out the inside path of the extruder body had some sort of material that was snagging the filament and it was slowing down the extrusion during a print. I found it by inspecting the extruder closely under a light and was able to drill it out. I have printed several small pieces of an item I am making and the prints look great when during this problem I couldn't get 3 layers to print right.

I did check my extrusion multiplier with the small square box .stl and that was perfect.

Thanks again,
Matt

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sthone
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Re: PETG clogs in extruder

Post by sthone » Sun Jun 25, 2017 12:48 pm

Nice I'm glad you got it figured out. :D

Perfect time to print a few spares drives too you should always have a few back ups of any of the critical printed parts just encase.

-Steve
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