Newbie here, Taz Workhorse. I would love to hear people’s thoughts on whether I’m missing something here or which of these issues to investigate first.Part way through most pla prints it seems to clog partway through. I’m just working on diagnosing what the cause is, these were the things I was thinking from what I’ve researched:
- Heat Creep - Tried pointing a desktop fan at it, may have slightly helped?
- I’m not sure which nozzle I have (got it secondhand), I have it on the default setting but it may be the steel one that needs more temperature. It may also be old, so maybe I should get a new one?
- Figuring out the z-offset - It always seemed to be a bit low, the first layer would sometime be dragging the nozzle. I gave it more clearance, but now I’m not sure if I’ve given enough or not.
- I updated the firmware (it was quite an older version prior), now it moves much faster
- I just have the default retraction settings, maybe that is still too much?
- Maybe I need to adjust the heat block or look more closely at it?
I’m trial and erroring the best I can the last couple weeks, but I’m hitting a bit of a wall. Any insights would be wildly appreciated. Thanks guys!
Jimmy
Pictures of the toolhead will help identify it. The workhorse has a lot of options. A hardened steel nozzle can require about +10-20c on the temp. Pointing a fan at the machine is not a good choice. It’s more likely to mess with bed adhesion and warping than help with heatcreep on the small target of the heatbreak.
You just updated firmware, did you write down the Z offset before and put it back in afterward?
If not, keep in mind that the offset is based on the washers above the bed (if printing on the PEI/glass combo) or slightly below (if using the octogrip magnetic sheet).
PEI/glass combo is typically Z offset of between -1.25mm and -1.32mm. Magnetic bed about 0.25mm
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Wow, thanks for the quick reply!
I’ll post a photo tonight with the nozzle
Sounds good, I’ll take a closer look at the heatbreak.
I did record the z offset, but I had also been moving it around quite a bit before that haha so not very useful. It was at -1.20 before everything though, but that was seeming low as the nozzle was sometimes dragging on the bed, and I had cleared it a bit more than that. Would too much clearance potentially cause a clog?
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If the nozzle is pressed against the bed, that’s enormous backpressure on the filament, but the extruder gears are just going to keep turning, it may just grind a groove in the filament, so it can’t push, stopping filament movement. That stopped filament sits on the heating element for a while, glazing the inside of the hot end (making future jams much more likely), or, before the filament strips, it shoves solid filament into filament that can’t move, causing a swell of soft filament that can’t be pushed out by the extruder to get ballooned out and jam. (Or both!)
As a bonus, once the filament stops moving, it’s not carrying heat down and out anymore, so heat creeps up the heatbreak faster, softening more filament, which lets the extruder push a little more filament in, lengthening the jam, which lets heat creep more… a vicious cycle.
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Once you have all of @Wrathernaut’s suggestions implemented, I have found on my TAZ 6 that PLA doesn’t mind some extra cool air as provided by an external fan after the first couple of layers.
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Here are photos of the print head (I think?) Seems pretty beat up to my untrained eyes
I know it has jammed on the bed in the past, but now they seem to be alright for initial layers. Should I take apart the hot end and do a clean there?
It’s a bit dirty, so I have to guess, but that looks like a brass nozzle to me, not hardened steel. I may be wrong, but I do not believe that Lulzbot has ever used a bare brass nozzle in their printers. They use nickel-plated or hardened steel.
Lulzbot is also very good about aligning the heatblock during installs, so those two things together make me assume that somebody replaced the original nozzle with brass, and did not install the nozzle correctly. Most likely, it was not tightened while hot, so the nozzle and heatbreak develop a gap when at full temperature, giving the plastic somewhere to creep into and interrupt flow.
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That would make sense! Should I take it apart and clean it up then you think? I’m sure I can find some walkthrough online
It’s worth a shot. Virtually any guide for nozzle changes for the e3d/v6-sytle heater blocks will work.
So long as it covers heat tightening in steps, it should be fine.
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Did a teardown, caked with pla everywhere. Also, the brass nozzle seems to be a 0.6mm?? (Four dots seems to mean 0.6mm, unless they mean different things). I’ll scrub it up, change my print settings to the 0.6mm nozzle and see if that helps. In the meantime, I’ll order the default nozzle and swap it out when it gets here.
Thank you @Wrathernaut so so much on this!
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