M2 clogged nozzle?? Extrusion problem.

[McSterls]

Printer is four months old, never had a problem. Printing PLA almost exclusivity did a small ABS print last week. Using stock temps in S3D, 215 for PLA, 235 for ABS. I have completed several large prints in PLA since running the ABS without issue, halfway through a good PLA print the nozzle seems to not be flowing properly and I got a very poor print, stringy and inconsistent, not solid- stopped the job and trashed it.

Originally thought it was a snag in the filament, checked it, tried again, now it's just printing garbage, stringy and inconsistent. Last night I printed PLA at 235 thinking the nozzle was clogged. PLA printed perfectly at 235, figured I had cleared the clog, shifted the bed, rotated the part and switched back to 215 - stringy and inconsistent.

I've attached a photo, the model in the back is PLA at 235, looks good, the model in front is PLA at 215. So is this a clog? Do I have to take the extruder apart to clear? Has this happened to anyone else? What's the procedure?

Thanks.
Mike

missed print.jpg (120.66 KiB) Viewed 2957 times

[Tim]

Too many swaps between PLA and ABS are known to be trouble, mainly because of the temperature difference. Any ABS left in the nozzle will not flow properly at PLA temperatures, so you can end up with a build-up of layers, baked onto the inside of the nozzle and difficult to remove.

Probably the PLA works at 235 because it's getting more fluid at that temperature and able to flow past the blockage.

In the long term, if you swap between PLA and ABS often, you should use cleaning filament between them to help clear out the residue. For the current problem, you can try running the nozzle temperature up to 255C (about as high as the V3b nozzle can take) and see if that will burn it out, but chances are that you need to give the nozzle a thorough cleaning. I've never done that, but there are a number of forum posts on the topic from people who have cleaned out their nozzles with tiny drills worked by hand, butane torches, acetone (for ABS), or methylene chloride (for PLA).

[McSterls]

thanks Tim, I will look around for cleaning directions.

[insta]

thanks Tim, I will look around for cleaning directions.

Cleaning the nozzle:
* Get some Taulman 618, cut about 2 feet off
* Pull the hotend out of the holder, but leave it plugged in
* Heat the hotend to 245C, no fans on it, hanging by the wires
* Grip the hotend (just gently enough to not slide around, do NOT deform it) with pliers
* Shove the Nylon in, apply firm pressure until you get a curl of Nylon out of the hotend
* Set the nozzle temperature to 130C, and keep applying pressure until the hotend falls to 170C ... this will likely use several more inches of filament, this is expected
* Let the nozzle sit at 130C for 5-6 minutes, then apply reverse tension on the Nylon to remove it from the hotend
* If the Nylon doesn't come out with firm pressure (grip the Nylon with your fingers only -- if you have to wrap it around a finger or use pliers its no longer "firm pressure"), set the hotend temp to 170C and keep pulling while the temp climbs, until it pops out
* Cut the "used" section of Nylon off, and repeat 2-5 more times, until crap stops coming out with the Nylon, and it can be cold-pulled at 130C

Seasoning the nozzle:
* Follow the first few steps of cleaning to have a pliers-held hotend
* Dunk the Nylon in some "boiled linseed oil" (flaxseed, mostly), and while the filament is still wet with oil, plunge the filament to the bottom of the hotend and immediately remove it from the barrel -- do not let the Nylon melt! This should be a half second process
* Plunge the same strand several times with the same oil on it, re-dip the oil every 6-8 plunges, and let the hotend rest 10 seconds between plunges
* After 30-40 dunks of filament, let the hotend sit in free air at 245C for 30 minutes ... put something under it to catch oil drips
* Cool the hotend to 180C and let it sit for 5-6 minutes once it reaches that temperature
* Do the cold-pull process one time with natural-colored PLA, using 55C as the low temperature and 180C as the hot temperature (instead of 245C and 130C for Nylon)
* Let hotend cool to room temperature
* Reinstall hotend into holder, do a sacrificial print with PLA or ABS (just a cube is fine) to flush the remaining oil out

Maintenance:
* Repeat this process every 10-15kgs of filament you use, or every clog
* Run a filament wiper -- holy moly this is important ... I use a piece of paper towel folded over several times pinched with a binder clip around the filament before it goes into the guide tube, nothing fancy
* Buy good filament ... good filament is not necessarily expensive (ESun), but expensive filament will probably be good

[McSterls]

very comprehensive! Thank-you, I'll give it a try this weekend

[psd]

thanks Tim, I will look around for cleaning directions.

Cleaning the nozzle:
* Get some Taulman 618, cut about 2 feet off

is the use of Taulman 618 very important or will any other filament work, like abs, pet, or plastic?

I don't want to buy a roll of Taulman 618 just for the cleaning

[insta]

is the use of Taulman 618 very important or will any other filament work, like abs, pet, or plastic?

I don't want to buy a roll of Taulman 618 just for the cleaning

Any PA will work. I think William @ intservo will sell samples for next to nothing. You use about a foot per nozzle-cleaning.

[psd]

super, thanks!

you should make a youtube video showing cold pull technique!

[Gwhite]

I've got a clogged extruder, and need to do a cold pull on it. However, Taulman 618 filament seems to have been discontinued. At least I couldn't find any 1.75 mm available, and Taulman doesn't list it for sale on their web site any more.

"any PA will work" OK, but folks need to know that "PA" is polyamide, which is the technical/generic name for Nylon. Nylon is Du Pont's trade name.

Taulman still makes a couple flavors of Nylon, but one is Taulman 230, which is a special low temperature formula that probably won't work with Insta's detailed process without tweaking the temperatures. I looked on eBay, and there are people selling small amounts of left over Nylon filament, but you probably need to dry it a good long while before trying to use it.

One weird option (if you can wait for shipping) is that you can buy 2 meter lengths of Nylon filament from China for less than $3 on eBay. I'd never buy it for a print job, but it might be good to have on hand for emergency cold-pulls if you can keep it nice & dry. I've got a spare extruder already installed, and will try this option.

If you think you might have occasional need to print Nylon and want to keep a small quantity on hand, Amazon has Gizmo Dorks 200 gram spools for $9.95. However, it's made in China and has mixed reviews...

[airscapes]

just bought a 1kg roll of Esun EPA off amazon.. wanted to give printing nylon a try as well as the ABS.. If someone wants a length for cleaning let me know (PM me)