WARNING: How to destroy your extruder nozzle instantly

Hey All,

Just a quick note on something NEVER to do, and a call for advice on how I should proceed…

I’m fairly experienced with 3D printing. My Taz 4 is the second printer I’ve owned and the third I’ve been solely responsible for operating in an industrial capacity. Recently, I swapped out a spool of SainSmart Dark Brown Wood filament for a spool of IC3D Green ABS filament. As always, I ran about 100mm of the ABS through the nozzle (at the higher temp) to purge it of residue from the previous filament. I printed several ABS objects for a university research project, but I noticed some slight porosity to the sides of the objects; areas where the filament had either delaminated, or failed to flow with sufficient volume.

I had observed this problem before (seemingly only with ABS) and I reasoned that the nozzle might be partially clogged. I elevated the Z-axis to a high altitude and began sticking the dental pick up into the nozzle from underneath (at temperature). I had done this before, so I figured it wasn’t a big deal. I was being delicate (or so I thought), and I did manage to draw out a few small scraps of blackened matter from the nozzle, so I was hopeful this had solved the problem.

Sadly, subsequent to this I discovered that the “noodles” being extruded by the nozzle were no longer thin and smooth, but rather fat and ugly. I had inadvertently “bored out” my extruder nozzle.

I stayed up all night tweaking settings in Slic3r and running test prints, trying desperately to get ANYTHING to print properly. I fiddled with the extruder nozzle diameter and extrusion width settings. I fiddled with the extrusion multiplier setting (outputs more or less material while printing). I tried adjusting the Z-gap and varying the amount of acetone/ABS coating on the platform. Of course I tried different extrusion and bed temperatures. Nothing worked. Evidently, I bitched that poor machine up royally, and it is now dead in the water. Having an extruder nozzle with the diameter of a firehose, it seems, is simply not a viable way to 3D print.

I speculate that my previous work with the dental pick might have done some damage, but this was the last straw that killed the printer. I believe that although I was being gentle, the fact that the nozzle was at high temperature made the metal (I believe they are aluminum?) more malleable and prone to damage in this way.

I strongly suggest never to insert the dental pick into the extruder nozzle from the underside. In retrospect, it was a very stupid thing to do, and it’s a mistake that’s going to cost me $100 and at least a week of downtime.

I do have a few questions for all of you; most of whom I assume are more knowledgeable than I am:

  • What diameter extruder nozzle would you recommend to replace it? I believe the factory one was 0.35mm. I don’t know what pros/cons exist for choosing a larger vs. smaller diameter. I’m guessing smaller diameter nozzles allow greater precision/higher detail, while larger diameter nozzles allow faster printing and perhaps less frequent clogs?

  • Any theories on what might have caused the ABS porosity problem? I stupidly gave the printed parts to my buddy at the uni without first taking any pictures of them, but I may be able to find previous examples to post pictures of.

  • Would a stainless steel nozzle be less prone to such damage, and if so, are there any that are compatible with the Taz 4?

  • Any sage advice on cleaning/unclogging a nozzle that’s not likely to damage it?

Please don’t feel obligated to answer all of my questions; any helpful hints would be well appreciated. I hope this horror story saves somebody the pain of doing what I did (not to imply that there’s anyone quite as dumb as I am on here!) :stuck_out_tongue:

~ Peter DeSimone
Chief Imagination Officer, Lyratron


I think .35 is kind of an optimum nozzle as it’s relatively fast and pretty good looking prints. For a faster print you can go to .50 but then you lose a lot of detail. For a more detailed print you can go smaller but then you must print slower and it takes more passes so the time to print goes up.

What caused it? Well I ran across a post not to long ago that talked about the wood filament coating the inside of the hotend with a goo, presumably sap that then burns and bakes into the nozzle and more. It might be OK with a .50 nozzle but I don’t think I would run wood filament through my machine unless I had a separate hotend for it. I know a lot of people print with it but it makes sense that sap would be squeezed out and coat the inside of the hotend and possibly clog the nozzle.

As for clearing a normal jam do a cold pull (search for it) if it’s loose debris causing the issue this will normally fix it.

Stainless is a poor heat conductor so not great for nozzles.

Don’t stick anything up into the nozzle unless it’s a micro drill of the exact size or smaller… Never mind, just don’t do it!

Thanks for the great info and thoughts, tmorris9! I will probably take your advice and get another .35 nozzle, but I’m very tempted to get a larger nozzle because I print in large quantity for commercial purposes and speed is a factor. I also can’t afford the downtime caused by clogging and I was hopeful that a larger diameter nozzle would clog less frequently. Then again, if .35 is the standard, perhaps the folks at Aleph have their reasons for that.

I’ve used the cold pull technique many times, but it didn’t seem to be working with this particular spool of ABS. At your suggestion I did some reading, and others recommend a cold pull temp of 160-180 C for ABS. I think I might have been pulling too cold, causing the filament to break rather than clear the nozzle.

Thanks again for the help!

~ Peter

.35mm nozzles give you a bit more fine detail on smaller parts. I use a .5 on my Taz for printing larger things. Most people who buy a printer print medium to smaller sized things at first, so a .35mm nozzle is going to give them better results. You only really notice the difference in small corners or overhangs. I can get very nice results wtih the .5mm one when necessary.

I use the .4 and .5 nozzles from makerfarm. They work great… the .5 can cut print times by a third. Not great for fine detailed project a like figurines or vases, but good for functional parts.

The one thing to beware of is the brass can splinter and clog the nozzle. Its happened on the .4 nozzles… And I’m guessing its something to do with the machining process. Regardless, removing the nozzle, an acetone soak (ABS), dental pick to clear the chamber (don’t pick at the nozzle opening) and a strand of wire to thread through nozzle opening clears the clog.

I like the .5 with layer heights of .2 or .3. Prints slightly faster and fewer clogs… Actually, I’ve gone through five spools of eSUM ABS (black, white and red) without a clog.

Thanks guys! I’m still on the fence about whether to get the .35 or the .5. Decisions… I’d better flip a coin or something, because I really must get this thing back online ASAP. Printing faster would be nice, but reliability is the real kicker. If the .5 is more reliable (clog-resistant), then perhaps I should go with that. Then again, not being able to print high-detail parts would suck…

Where would one even go about getting a 0.35 mm nozzle?

I bought a 0.3, 0.4, and 0.5 from www.makerfarm.com (although haven’t actually used one yet… hopefully this weekend).

Regarding the wood filament, it does say (either on the lulzbot website or the packaging itself) to put it through a 0.5 mm nozzle for best results.

Lulzbot sells a myriad of nozzles from .25 to .75:


Thanks for the tip about wood filament. I didn’t see that anywhere, but I think I’m gonna stop using it anyway. No real advantage over PLA that I can tell. It looks more like brown plastic than wood, and it tends to splinter under stress, whereas PLA at least has some beneficial elasticity. The only nice thing about it is how it smells when printing. But then PLA doesn’t emit much of an odor, and what it does emit doesn’t smell bad either…

I just purchased the 0.5mm nozzle. I actually got a whole new Budaschnozzle because I’ve been abusing that thing nonstop for over a year, and the damage likely extends beyond the nozzle tip itself. This way, I can put a new nozzle tip (probably a 0.35) on the old one and have a backup that I can swap out quickly. This will minimize downtime whenever the resistive heating element fails (I’ve changed it once already), the thermistor dies, the nozzle gets a bad clog, etc. I’ll be printing again in 5 minutes and can fix the down hot end at my leisure.

Thanks again, everybody, for the great advice!

I have a set of cheap micro drill bits that I use in a dremel drill press to bore out worn or damaged nozzles. I have a bunch of .35 nozzles bored and remarked to .40. Making profiles is easy for ABS, just figure your adjustment from one nozzle size to another (.40 divided by .35 = 1.143), load up a .35 profile and find width figures, and multiply them by the adjustment number you came up with (1.143). I have .50 and .40 profiles for ABS that I made that way then made small adjustments later (top solid thickness seems to like another 20% for a nice smooth print)

Thanks, gghouck! Yeah, I was actually going to ask you guys what slicer settings are recommended for the 0.5mm nozzle. My default plan was to try exactly what you recommended, so I guess my intuition is good. :slight_smile:

I have .31 and .22 layer height profiles for an ABS .5 nozzle.
Medium_ABS_no-support_pt50nzl_pt22layer.ini (3.3 KB)
Medium_ABS_no-support_pt50nzl_pt31layer.ini (3.3 KB)

Thanks a lot for sharing those profiles! I will definitely give them a try. Can’t wait to get that new nozzle so I can get this printer back online.

I think I’m going to feed it nothing but ABS for awhile, since I’ve heard reports of clogging both from PLA (especially if run too hot or left sitting in the nozzle for too long), and from wood filament. Could be wrong, but I don’t think ABS oxidizes / chars nearly as quickly as those other filaments. I just want this thing to be reliable, i.e. as close to zero downtime as possible.

~ Peter

The .5 nozzle prints some pretty strong parts at .3 layer heights and speeds up print times. Less clogging. Printing slower at .1 and .2 provides good detail. Its a good general use nozzle from my experience.

gghouck, I tried your Slic3r settings… they work great! Thanks again. This thing is printing better than EVER! It hasn’t printed this well since I first got it. Porosity and layer separation problems are gone, suggesting strongly that all my problems were the result of a clogged/damaged nozzle. Thanks everyone!

I’m glad they worked for you. I plan on using the same method to make .55, .60 etc configs when I have to drill nozzles out to those sizes.