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madoverlord

New user -- tremendous clogging problems

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I've only had my Ultimaker for a few days (albeit I have been using it a lot) and have already had two major clogs in the hot-end.

The first I was able to fix by setting the temp to 250 and manually feeding. This got me back running for all of a day.

The second one I haven't been able to fix at all. I've disassembled the hot end (twice!). The first time I found a clog in the teflon adapter. Removing this did not fix the problem.

The second time I completely cleaned out the hot end -- set the temp to 250 and used a long 3mm bolt to scoop out everything I could. I also used the bolt to push through the residual plastic, and I think I got it all because I was seeing little puffs of burned plastic smoke come out of the nozzle.

I reassembled and tested using the control panel, and it extruded fine, though it tended to curl up into little thread clumps instead of just dispensing vertically.

I started a print. The outer boundary was thin and did not adhere.

I stopped, readjusted the bed to make sure it was the right height, and started again. Same problem.

I stopped, lowered the bed, and tried to extrude. Nothing.

I tried manual extrusion. Nothing.

It's 100% clogged again.

At this point I am at a loss.

I have a brand new machine which apparently has a V3 extruder.

Thanks in advance for any help you can provide.

 

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1) what kind of plastic are you trying to print

2) Which program are you using to slice

3) how big is the part (ie now long are the prints)

4) What temperature are you trying to print at

5) Do you have the fan on, if so after how many layers

6) Did you make sure that there are no gaps in the hotend when you assembled it

7) Have you checked you assembled the hotend correctly ? You can get the orientation wrong I believe

with the new hotend

8) what print speeds are you using

9) Pictures help alot,...take pics of your hotend so we can see how you have assembled it

We are not really interested in what you did to fix the blocks, but more what you were doing when they happened.

Also, there are ALOT of old threads on this stuff...have you checked them yet?

 

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In addition to what Calum asked, what print settings are you using to slice? How fast, and what layer height, nozzle width, wall thickness settings?

Also, when testing extrusion, I highly recommend only turning the big gear wheel by hand. Don't use the ulticontroller, because I find that can very easily end up forcing too much plastic through the head too quickly. That can immediately cause more clogs by increasing the pressure in the head and causing molten plastic to squirt back up into the colder parts of the head. If you turn it by hand, you'll start to feel the back pressure as you turn, and can slow down a bit.

Also, when you have extrusion problems, be sure and remove the plastic from the bowden and check that it's not damaged. Cut off any damaged parts that might have been chewed up by the extruder drive. They will just cause more problems.

 

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Thank you for your quick responses. I did search for other threads but apparently I was too specific.

In response to your questions, I am printing PLA (the silver that comes with the Ultimaker), using the default settings. The only things I am adjusting are options like support, top and bottom thickness, and wall thickness. The fan is coming on automatically as far as I can tell, but the problem isn't printing per-se: it's been printing wonderfully, doing long multi-hour prints, but now it has just started clogging -- so far twice in the last two days.

As I mentioned, I found a plug-up in the white teflon part the first time. After reading your posts, I disassembled the hot end again. This time I could not manually retract the PLA; I had to remove the bowden tube and then found that the end of the filament had thickened a bit, making it too thick to retract.

I have once again completely cleaned the entire filament path, and removed the tip and cleaned it out as best I can. However, I won't reassemble it just yet, pending further comments and suggestions.

In particular, regarding: "6) Did you make sure that there are no gaps in the hotend when you assembled it", are there more specific instructions than given in the assembly instructions for ensuring there are no gaps? Are there specific things to be on the lookout for? I am wondering if the problem is in the interface between the white teflon part and the PEEK part.

Here are a few photos of the hot-end, which may be helpful.

https://www.dropbox.com/s/p3ws3vk8wftndzo/IMG_0426.JPG

https://www.dropbox.com/s/zykcsz8ppn02mpz/IMG_0427.JPG

https://www.dropbox.com/s/mw29zvvv14ujhg0/IMG_0428.JPG

https://www.dropbox.com/s/a7zdhnwveq21re7/IMG_0430.JPG

 

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What default settings, specifically? What speed, and what wall thickness and layer height? Those settings can make a big difference to the amount of plastic you are trying to extrude per second, and can cause problems - I've seen several users now who had huge problems (to the point of 'I'm gonna throw this $#^#^$% printer away') until they found some speed settings that didn't ask too much of the printer.

 

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The Cura defaults, as set by the first run wizard.

Print speed 50 mm/s, Temp 220, Filament diameter 2.89, packing density 1.0, retraction enabled, 0.2mm layer height, various wall thicknesses depending on the print.

The only setting I have changed from the defaults in prints have been wall thickness, bottom top thickness, fill density, and support settings. Often I am just printing with the basic High Quality setting. The problem does not seem to be related to those particular settings, especially when you consider that after I cleaned the second clog out, it reclogged within seconds of starting the first print (which leads me to believe perhaps the hot-end did not get put back together again correctly in some subtle way)

The printer flawlessly printed for 3-4 days, probably about 30 hours of printing, before the first clog. The only problem I had was an occasional first layer or perimiter not adhering; stopping the print and restarting it would always fix this.

 

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Sorry for seeming pedantic about it, but the settings do matter. :-) For instance, if you're printing with 'high quality' settings from the quickprint mode, then iirc, you're printing 0.1mm layers, not 0.2mm layers, and I don't think any of those modes use retraction at all. The wall thickness you specify could make a difference as well, if it's not an exact multiple of the nozzle width. (See my blog post here for more details about the effects of non-standard wall thicknesses in current version of Cura and how it can cause problems).

It doesn't sound like you're printing at speeds that should be causing problems by themselves, so it could be an issue in the assembly of the hot end... most likely in the interface between the bowden tube and the teflon part I think, although in general new hot ends are really pretty reliable, so long as you aren't printing very fast, or very slow.

What is your procedure when you're getting ready to print again after fixing a problem? How do you prime the hot end with plastic? Do you manually insert the filament, and turn the drive gear by hand, or are you using an ulticontroller or Cura etc to drive some plastic through the nozzle. The latter should be avoided because it can quickly overload the hot end (default extrusion speeds are much faster than the nozzle can handle). If you simply turn the gear by hand, you can feel resistance when you are turning too fast, and can slow down a bit. This avoids forcing molten plastic back up towards the bowden tube. (I've had this happen, the one time I thought it would be a good idea to use the ulticontroller to help load filament - I got three clogs one after another even while trying to get ready to print again).

 

The Cura defaults, as set by the first run wizard.

Print speed 50 mm/s, Temp 220, Filament diameter 2.89, packing density 1.0, retraction enabled, 0.2mm layer height, various wall thicknesses depending on the print.

The only setting I have changed from the defaults in prints have been wall thickness, bottom top thickness, fill density, and support settings. Often I am just printing with the basic High Quality setting. The problem does not seem to be related to those particular settings, especially when you consider that after I cleaned the second clog out, it reclogged within seconds of starting the first print (which leads me to believe perhaps the hot-end did not get put back together again correctly in some subtle way)

The printer flawlessly printed for 3-4 days, probably about 30 hours of printing, before the first clog. The only problem I had was an occasional first layer or perimiter not adhering; stopping the print and restarting it would always fix this.

 

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Check for dust that can cling to your filament. Maybe some dust got onto the filament. It can get statically charged and then dust sticks to it, gets into the print head...

Also open your feeder and look to see if the wood is getting ground up. Sometimes the knurled bolt can chew up the wood and splinters get into the hot end.

Look at this filter and how much it snagged - tape around toilet paper around filament:

https://lh4.googleusercontent.com/-6gJHBP0QHes/UWSHi2Gsm9I/AAAAAAAAAEM/2xPR1w6MrGQ/s1600/shit.jpg

If you unscrew the nozzle, make sure the block is at least 180C first.

 

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OK, I disassembled the hot end, cleaned it completely, and put it back together again. I followed the advice given above about manually turning the extruder gear, and plastic did start extruding. I re-zeroed and re-leveled the bed, and started a print.

The perimeter line had a big blob at the start, and the normal behavior (a thin thread from the home position to the start of the perimeter) did not occur. The perimeter was a bit thin, and the same could be said about the first layer, the filament lines being laid down were thinner than normal, and seemed to be getting thinner -- my guess is that the flow was not as large as it normally would be.

I stopped the print on the first layer, rehomed the head, lowered the bed, and tried to manually turn the extruder gear to extrude a bit more filament. No filament extruded, it was blocked again!

I reversed direction on the gear, and the 2.89mm filament came out of the hot end without any resistance. I tried manual feeding, no luck.

Upon close inspection, I could see a plug of plastic that reached right up to the bowden tube. As you can see from the linked photo, it has a lip on it that appears to be where plastic got between the tube and the teflon part.

https://www.dropbox.com/s/2swy38ifvtgkqg7/IMG_0431.jpg

I removed this obstruction and reassembled, but the extruder is still blocked.

My guess at this point is that there is some obstruction in the tip that I have not been able to remove, and that this is causing the thin feed followed by a backup and a clog.

Does anyone have any advice as to how to completely clean the tip and/or determine if it needs to be replaced?

 

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I am highly suspicious about your hotend temp.

If you can be bothered to do so, I recommend boiling a cup of tea (obviously dont bother to put the tea in)

lower your bed to the base and immerse the thermocouple in the just boiled water.

Obviously it should read about 95 Deg C by the time you put it into the mug and did the rest.

Just one possibility....

 

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I've never had to disassemble so hopefully someone else more knowledgeable will reply. But if you heat your block to about 180C can't you just unscrew the nozzle? You probably want to wear gloves and use your fingers so that you don't break anything (I hear brass breaks easily). Then while it's hot maybe you can run PLA backwards? Blow compressed air? Let it sit pointing up at 200C on something hot? I'm not sure how to clean it.

There is a solvent that should work if you can find it:

tetraHydroFuran THF

But the clog is probably something that doesn't melt at 200C such as wood chips, dust, sand.

 

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Yes, but its not very nice.

Take off the nozzle, and hold it with pliers or whatever over a candle flame for a few mins.

Unless what is in there was metallic blocking it, it will get carbonised and turn to ash.

Clean it up as best you can, reinstall and flush PLA through by turning the extruder wheel by hand with the hotend at 220C or whatever. Probably you will get black rubbish coming through for the first few cm of filament.

Also what I have done when I got a 2nd hand V1 hotend to build my dual setup (it was full of old solidified PLA).

was to put in a vice, and hold a solering iron against the nozzle.

Then I was able to pull the "plug" of PLA out with tweezers. This pretty much pulled out most of what was in there

at the same time.

 

 

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OK, happy to report that the problem is solved.

As per snowygrouch's suggestion, I removed the tip and "candled" it, then ran a hot wire through the orifice. I also used an old drill bit to auger out the inside of the tip (heated tip and drill bit, inserted into tip and rotated to extract leftover plastic).

I then put the tip in a toaster oven for 30 minutes at 400F, soaked it in acetone overnight (because why the hell not?) and lightly sandpapered the cone of the tip to remove any residual carbonized crap.

After reattaching the tip, I turned the temp up to 250, waited 10 minutes, and then manually fed a little filament, and it started extruding. After it stopped, I fed it a little more, and repeated this cycle several times. I then reduced the temp down to 220 and did more extrusion cycles.

First test print had some irregularities in filament thickness, but I let it run for several layers and it seemed to settle down, so I cancelled the print and restarted it.

The result speaks for itself...

https://www.dropbox.com/s/8zp6nzlscx0fggf/IMG_0434.JPG

Many thanks to everyone who has contributed to helping me address this issue.

 

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Looks great !

The trick to determining what the likely cause of a plug is, is the time it takes to develop.

When you were getting almost instant plugs, this is a sign of a physical particle blocking the nozzle.

When you get the "traditional" plug, caused by *blah blah blah look at the threads on that stuff * it will

develop slowly and starts with slight under extrusion and can take hours of printing to result in a full blockage.

Glad it works.

 

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Just a followup. After some months of flawless operation I finally got another clog. I tried the usual things -- heating, candling, THF, but couldn't get whatever it was that was blocking the nozzle out of the tip. After trying to poke stuff free with a thin strand of wire like last time (a royal pain in the ass), I decided to use my head. I went to McMaster.com (probably the best place in the US for getting parts and tools online) and got a selection of very, very tiny drill bits.. #80, #79 and .0150 (the Ultimaker nozzle hole is .0157 IIRC). They are about $3.00 each.

I clamped the nozzle to a soldering iron tip with a binder clamp, let it heat up, and then, holding them with needlenose pliers, gently pushed the drill bits into the nozzle (without rotating them, as I did not want to damage the nozzle hole) and moved them up and down a few times, first the #80 and then the .0150.

After letting the nozzle cool, I blew some air through it using my Mk.1 compressor (lungs!), reinstalled it, and it prints fine (so far, cross fingers)

 

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