Nonfunctioning tool head

New Sidekick 289. After a few successful prints the SK175 tool head no longer loads filament. After feeding maybe 1 cm, it stops (the gear keeps turning). On inspection after unloading, the tip is chewed up. I am certain I have it properly adjusted as instructed by the Lulzbot tech service. I think it is permanently plugged and probably unfixable. Any suggestions? It is under warranty, but a hassle to send back for service.

Newb here. But based on your description I am confused. Did you unscrew the filament tensioner all the way and take a gander inside?

Have you tried heating up the nozzle and using purging filament?

When you say “the tip is chewed up” … which tip?

Does ANY filament extrude? I’m trying to work out if you have a dirty hobbed gear vs. a clogged nozzle.

The hobbed gear has teeth that can clog up with chewed up filament and when that happens the gear no longer grips the filament. It’s really easy to clear because that happens where the filament was still cold – nothing is melted to the teeth. I use a can of compressed air and give it a few puffs and it clears out all the bits that might be in the teeth.

You would need to remove the filament, cut it back a bit to get to clean (non-chewed) filament, and re-load.

Also… which filament are you using and what temperature?

As for the head … LulzBot printers use modular print-heads. The entire head is attached to a carriage on the X-axis rails. It is held in place by just three screws… two on top and one at the rear. There’s a single wire-harness at the top of the head that plugs it into the mating side of the wire harness located on the carriage. So… you unplug the wire-harness, remove three screws, and the entire head is off the printer.

I do this frequently to swap between my .25, .5, .8, and 1.2mm heads without having to go heat up the heat-block to swap extruder nozzles. So if the head really does require service … you wouldn’t need to send in the entire printer. But hopefully this is something you can clear on your own.

I can’t see what’s going on beyond the tensioner screw even when totally unscrewed. And yes, even with the nozzle at 210 nothing extrudes or purges, because filament never loads.

The tip of the filament that won’t load is a bit shredded, crimped, and often has a small bite out of it.

The hobbed gear is clean, so that’s not the problem.

I’m using filament that came with the printer, at temp 200. I’ve also tried with other PLA. None of them load.

I did remove the head the head. I tried to remove the nozzle so maybe I could clear the clog from below, but I was unable to loosen the nozzle. It seems frozen. What I need is a replacement SK175.
The one I have is probably clogged beyond repair.

I have addressed all of these possible problems. Bottom line: I think this tool head is hopelessly clogged. Nothing extrudes or purges, since plastic doesn’t advance past the hobbed gear. When I unload it, it’s the tip of the plastic that’s damaged, or course. It’s often bent, shredded, and often with a small bite out of it. I always cut it back clean before trying again, naturally. I have made at least 20 attempts, all failures, using the PLA you sent me and also my own: 1.75 mm, temp 200.

I have removed the tool head and tried to remove the nozzle, thinking I could clear the clog from below. However, the nozzle is absolutely frozen and won’t unscrew.

I would be happy to send you the tool head for repair or replacement. I believe it is still under warranty. This problem is beyond my knowledge and ability.

The nozzle is heat-sealed to the hot-end. It must be heated to high temperature to remove it. Do not attempt to remove when cold.

To feed in fresh filament, it really helps to use nippers to cut the filament diagonally on each side to make a “v” shaped point.

If the nozzle is clogged, you can often clear it by performing something called a “cold pull”.

Ideally, use a clear (aka “natural” filament that doesn’t have a colorant added) and the favorite filament is Nylon. (Nylon is difficult to print because it LOVES to absorb moisture out of the air and this is problematic when getting clean prints. But as a cleaning filament, it works great.)

To do a cold-pull:

  1. I swap the filament for a “cleaning filament” (I use Nylon… not strictly necessary but it has advantages). So you’ll remove the filament an insert your “cleaning” filament.

  2. Heat and fully insert the cleaning filament. It should be thoroughly melted in the hot-end.

  3. Allow the hot-end (and filament) to COMPLETELY cool.

At this point, whatever is clogging the nozzle is now melted into and imbedded within the cleaning filament.

This is the most important … and the point of the “cold” pull. As filament heats, the bits of filament touching the hot-end will melt first (the core melts later). So the MOMENT that the filament has melted enough to break free … you need to pull it out.

  1. Loosen the hobbed-gear tension. Start heating the hot-end again.

  2. As the temps approach the softening point for the filament, release tension (I pull the tension wheel away from the hobbed gear) WHILE pulling up on the filament.

  3. The filament will break free of the hot-end and pull up … pulling whatever has clogged the extruder up with it.

You don’t have to use Nylon and you don’t have to use a clear, un-colored filament … but using clear filament means you can inspect whatever it pulled out. Usually one “cold-pull” is enough… just occasionally you might need to do it twice.

When extruding through a pristinely clean extruder, the filament will extrude straight out. If you notice the extruded filament trying to squirt slightly to the side… you have a partially clogged nozzle.

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Another possibility is that previous heat creep has caused filament to melt in the cold end and get stuck there. This can often be cleared by purposely causing heat creep by blocking the cold end fan while heating the nozzle to the temperature used by that filament. After about 10-20 minutes, attempt to feed fresh filament (I use cleaning filament for this) and if successful, unblock the cold end fan, turn off the heat, and keep extruding filament (don’t want the fresh filament to melt in the cold end again). Do a cold pull at around 110 degrees (for PLA). Another cold pull or two after this should clear things up.

Having cleaning filament on hand is, IMO, a wise investment. You can find some in the LulzBot Store or search online for other brands (I use eSun). You can search this forum for “cleaning filament” for other ideas and techniques.


All of this is beyond my comprehension. If you will not fix this for me, I must abandon all hope and discard the printer. Too bad, I was really enjoying this.

You said in your original post that the printer is new and under warranty. Contact LulzBot support and arrange to send the tool head back for repair under that warranty. You could send the whole printer back instead if you want.

If you have decided that 3D printing is beyond your comprehension, then box up the printer and offer it for sale.

The people on this forum are very knowledgeable and we are happy to help you comprehend the issues you will face if you are willing to take the time and learn.

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Pretty condescending response.

When I say I’ve tried all suggested fixes without success, that’s true. I’ve invested a lot of time trying to fix this, despite your implication that I am lazy. I am neither lazy or stupid, but I am no engineer and certainly not
savvy regarding 3D printing machines. I have been at this hobby for over a year, with Crealty before you, which printer never worked, and I find it barely worth the money, time, and effort I have put into it, so far. Needless to say, I am disappointed that your printer, advertised as user friendly, is prone to this kind of malfunction, and so soon after I began using it. And BTW, I have read other posts complaining of the same type of issue, so I am not alone.

Perhaps there’s a misunderstanding here – this is NOT Lulzbot’s technical support forum, this is a user-to-user community forum.

The people with whom you are coversing are just other users of Lulzbot printers. From time to time, an actual Lulzbot employee does pop into this forum, but they do so out of courtesy and curiosity, since this is not the official Lulzbot support site.

I appreciate your frustration – but you really need to contact the Lulzbot support team at their support email or phone.


Creality brand printers are in an extremely low-cost price category … where the priority is making things as cheap as possible. In some of my other 3D printing circles I heard the snarky comment: “Creality are great printers… because of them, I learned everything about how to fix 3D printers.” … and yeah… the occasional printer might show up to a consumer in perfect working order, but most of them need a bit of help.

LulzBot printers are at a higher price point and a higher quality point … but also, LulzBot printers have support. You can actually get through to them. This means LulzBot spends more money by providing support staff … and that factors into the price.

3D printers aren’t for everyone … and I don’t mean that as an insult. You can pick up an inkjet printer, plug it into your computer, and it will probably “just work”. There’s nothing too difficult about using them (aside from ink nozzles drying up all the time … but when they work, they work.)

3D printing is a bit different. You are making creations by melting polymers or co-polymers in just the right way and moving the print-head at just the right speeds, etc. etc. It’s a learning experience.

LulzBot produced a number of filament print-profiles that are tested and should provide pretty good starting points for most prints. I tweak them a bit … but overall they are pretty good.

You mentioned you are just trying to use the sample filament that came with the machine … that should be PLA (unless they’ve changed it – but I can’t imagine they would because PLA is the easiest filament to achieve good results).

But 3D printing involves a bit of trial & error testing and to avoid frustration – such as now – it’s nice to know how to diagnose common problems because in 3D printing there WILL be a lot of common problems.

Knowing how to do a cold-pull is a fairly basic … but important skill. You wont have to do this often, but when you get a clog … yeah, you need to know how to do this. Because a simple cold-pull is a lot faster and cheaper than having to send a print-head in for service.

You said you tried “all” the suggestions. But when I mentioned the cold-pull, you gave a response that suggested you didn’t understand it. Did you try that?

If your nozzle is clogged, then this is one of the best ways to clear it. It takes a few minutes and it isn’t difficult to do … just take a few moments to understand the process (watch a few YouTube videos … there are numerous tutorials).

You could probably disconnect the head and send it back to LulzBot for help… but if this is just a simple clogged nozzle, that would be a huge waste of time. I wouldn’t send it in for service unless simple steps to clear a clog had been attempted.

As for that clog… it is usually never necessary to remove a nozzle to clear a clog. The only exception I can think of is the use of PVA “support” filament. This is only used in dual-extruder printers – so it’s not something you would encounter on a single-head printer.

As you gain experience with 3D printing, you learn to avoid clogs and very seldom need to clear them.