changing nozzle size

Hello all!

anybody have any idea whether the nozzle on the lulzbot mini can be changed from the standard 0.5mm?
Im thinking of going down to 0.2 or 0.15 mm.

I need to print 3d models with small features and the 0.5 mm


As far as I’ve been told by Lulzbot, it can be done, but it’s not easy/pretty.

I was thinking of the same thing, though maybe not .15! I was looking at these wondering if they the right nozzles:

What is ugly about changing this? It looks like you just heat up the hot end, unscrew the old one, and screw on a new one. What am I missing?

From an email conversation I had with Lulzbot support;

“Disassembling the hexagon hot end (for nozzle swaps, etc) is something we cannot recommend either. We use a torque wrench to 30in lbs of torque, and a high temp thread locker rated to 2100f. If these guidelines are followed on re-assembly (tools we can’t expect customers to have) leaking will occur. This can not only affect quality, but the automatic bed leveling process as well.”

If you’re comfortable with that, knock yourself out! :slight_smile:

So if changing the nozzle is not recommended, then what is the best way? I wanted to switch to a smaller nozzle as well. Although I would prefer a way that makes it easier to go back and fourth from a .25 to the standard .5 nozzle. I occasionally print parts where the .5 is just too big and would like the ability to switch to a smaller size when I need it.

I haven’t even tried disassembling the extruder head and hot end to see what the best option would be for switching nozzle sizes with the least amount of work. I’m hoping someone can make some recommendations. I don’t mind buying some spare parts to make the swap easier. I was looking at the full extruder head that they sell in the store here but I don’t see a hot end offered anywhere with optional nozzle size. Maybe I’m missing something.

Thanks in advance for any advice.

Changing the nozzle isn’t for the faint hearted… but if you’re mechanically savvy, its not hard. As a comparison, using the .5 nozzle with a layer height of .3-.4 will reduce print times by a third. This combination also yields really strong parts (ABS) and are suitable for large mechanical parts not requiring a lot of detail.

Here’s the process I follow to remove and swap nozzles:

  • Gather the tools: 17mm wrench (18mm works also), 7mm wrench, silicon pad, vise-grip or large locking forceps
  • Heat the hotend to 165C+, raise hotend to comfortable working level
  • Place silicon pad or whatever protection over bed to reduce damage from dropped tools (18mm wrench can be heavy) or the hot nozzle.
  • Remove nozzle, 18mm wrench on heater block and 7mm wrench on nozzle - the nozzle will be hot.
  • The nozzle wiill be hot - Use vise-grip or locking forceps to grip hot nozzle before final removal from heater block
  • Thread new nozzle onto heater block (still 165C+) - Best to do this with bare fingers rather than tools to ensure the nozzle is threaded properly. The brass is soft, so make sure you don’t cross-thread… there’s a slight resistance, but if its too great… stop and try again. Also note the nozzle will get hot after a few seconds of trying… just remove and let cool start over.
  • Once the nozzle is on, heat the hotend to 270C+ and use the wrenches for one last good firm twist.
  • Go back to printing.

That’s pretty much it… sometimes easier than it reads… :slight_smile: I do this fairly regularly with no issues… but YMMV. And as posted above, not recommended by LB supportso perform at your own risk.

Last tip: Having two of every nozzle size reduces down-time due to clogs.

Do you re-apply any threadlocker?

I don’t put threadlock on the nozzle… I think LB puts some sort of threadlock on the heat break.

Ok. I was under the impression they thread locked the nozzle after talking to them a few weeks ago.

Do you have to make many adjustment to Z offset and first layer thickness when you change nozzle sizes? I need to move to a 0.4mm. The 0.5 is a little to big for the thin walled parts I need to print.

If you read closely it is the hot end they thread lock. If you are only changing the nozzle it is not thread-locked, and if you are careful will not give you problems. But I have worked on a couple hot ends that are not flush on the bottom surface and leak PLA easily on reassembly. The torque wrench setting is for the nozzle though.

Yesterday I was looking up thread lock and found some blue 2100F product – when I look closely at the hot end, between the block and the cooling fins you can see a blue residue. But there is none of that around the nozzle. Thanks for confirming where the thread lock goes (one product was a two part mix reminding me of epoxy and making me think it would be a real bear to get off).

Anyway, thanks for posting detailed instructions. I’m definitely going to try this.

The PDF manual has directions on how to change nozzles. Interesting that support makes it sound so scary.

Are you saying this Locktite is rated for 2100F? No Locktite is rated for over 450 Deg F.

From product page:

Range, °F

-300° to 2100°

Locktite is a brand name. I looked back in my history but couldn’t locate the two part epoxy like substance, I did however find these two products as some of the ones I looked at:

I can’t remember if this was linked above, but the assembly process of the print head is informative:

According to the OHAI kit page: Lulzbot uses Resbond 907TS – if you open up the PDF for the cotronics product (first link), you’ll see there is a blue version.

I finally went ahead and tried this using kcchen_00’s instructions (repeated below) because I was having an increasingly difficult time getting good surface quality. I’m so glad I did, it was really easy and my prints are a lot nicer now. By comparison I was doing a lot of tweaking in expert settings before, for my first test, I just used Cura’s basic settings and it still came out very nice – much cleaner and uniform than I had been getting.

I also noticed that when I removed the old nozzle, it took almost no force to get it off. When it is cold it seems like it is tightly attached because of the plastic, but when it was hot I could have easily taken it off with my fingers, heat being the only impediment to that. I wonder if over time, the wiping sequence can loosen the nozzle. Anyway, I’m going to add checking the torque setting on the nozzle to my periodic screw tightening check.

I made one mistake though – I should have done a cold pull of the filament. My old nozzle is full of filament so it’ll probably take a week in acetone to dissolve it out so I can clean it up.

[/quote] I made one mistake though – I should have done a cold pull of the filament. My old nozzle is full of filament so it’ll probably take a week in acetone to dissolve it out so I can clean it up.[/quote]

Heat it at about 200C in the oven or using a lighter and extract the remaining melted plastic using a needle. Later you can burn it using a gas torch. It will remove all the remainings. Later clean it very well and ready!

Get a dental pick. Soak then pick out the acetone, repeat until nothing is removed.

Recently got brave and started drilling out the filament. Start with a small bit to create a pilot hole (the ABS is soft so this may not be necessary) and work to a bit size just shy of the nozzle diameter. This should leave a thin layer of ABS for the acetone to work on. Soak and pick. Of course, be mindful not to damage the soft brass of the nozzle.

Lastly “floss” the nozzle opening with a solid core wire or a few strands of wire. 28AWG magnet wire works well and solid to get through the nozzle opening.

Hope that helps!

The risk of stripping the nozzle threads if you do it wrong is very real. On the pre-mini buddaschnozzle hot end that often meant buying a new hotend, or at least enough of one that the cost was about the same. With the hexagon you are more likely to just strip the threads off the nozzle itself, which can then be removed from the hot end body with a pick.

Thank you all for the additional tips. I’m prepared to accept the consequences if I bork my hot end – won’t be the end of the world.

I’ve now soaked/picked out all of the filament. I have a carbonized burnt on residue remaining. Will that come off if I burn it in a torch? I was thinking of getting some superfine bronze wool to polish the outer surface, but what should I do about the burnt on stuff caked to the inside walls? I imagine I could get some of that with thin fingers of wool, but are there better ways to go about it?

Second question, has anyone tried boring out the nozzle to make it larger? I’m sort of curious about what a 0.75 or 1.00 mm nozzle might do. Usually I want a nice smooth outside surface, but I can imagine a strongly striated surface might also be pleasing, and a 0.5 mm or thicker layer height would be darn fast to boot.