Lulzbot Taz Pro Printing Airy and jerking erratically

Hi Forums, so Recently been attempting to repair a pair of basically factory new Lulzbot Taz Pro’s the issue with both of them is unique as with one, the printer jerks around erratically while printing often ruining prints, while with the other prints come out airy and of poor quality (picture attached for explanation) printing using PLA (Verbatim) and a .50 mm nozzle with default print settings in Cura for a Taz Pro with that nozzle size. Please advise

There’s not a lot to go off of, some video would definitely help.

Jerky motion - is it only when printing, or does it do it if you just manually move around from the control panel? How about when running from SD card? If it’s limited to when it’s being run by a PC, your machine might not be sending commands freely via USB, try running via USB thumbdrive. If it’s only when printing, with either thumbdrive or PC connection, is it the nozzle dragging across the existing print? Ridges caused by overextrusion can catch and interfere with the printhead’s motion and/or cause the print to be torn off the print bed. There’s also loose belts, an un-square Y axis, or something catching the bed or gantry and interrupting movement.

Airy prints on the other hand, sounds like underextrusion. If your slicer is set for 2.85mm filament, but you’re using 1.75mm, it’s going to greatly underextrude. If the slicer is set for 2.85mm and you’re using 2.85mm filament, check your extruder steps/mm. It should be really close out of the box, but if the machine has the wrong toolhead selected (with the Universal Firmware) or the wrong non-universal firmware is loaded for the attached toolhead, the extruder steps is almost certainly wrong.

A video really would help.

I’ll try to address the topic of “jerking around”. The slicer (e.g. Cura LulzBot Edition) will send the print-head moving around to different areas of the parts. But you have some control over how this happens to avoid damaging the part.

  1. In the ‘Speed’ section of the slicer settings you’ll find the “Travel Speed” – this is the speed of the printhead while doing a non-printing move. In my slicer settings it is set to 170mm/sec.

  2. In the ‘Shell’ section of the settings you’ll find “Optimize Wall Printing Order”. It is normally not enabled … I almost always enable this as it tends to result in the printhead finishing walls in one area before moving to the next (less jumping around.)

  3. In the ‘Travel’ section of settings you’ll find an option called “Z Hop When Retracted”. This causes the print-head to lift just slightly above the top of the part surface at the end of a printing move before it starts a non-printing move – so that the nozzle will not drag over part surfaces. This means the head should not damage the part when moving. But this does slightly add to print time.

As for ‘Airy’ prints … a quality photo would be really helpful. Filaments can absorb moisture out of the air (and some filaments are know for being problematic with this – although PLA isn’t one of them.) “Wet” filament (we call it “wet” even though it will appear to be completely dry until you try to print with it) gets moisture absorbed into it. When that moisture goes through the hot-end it boils … and creates air-bubbles in the filament. The filament has to be “dried” out using … usually using a filament dryer or a food dehydrator. Drying is typically done at very low temperatures because you don’t want to melt the filament – many filaments are dried at temps no warmer than 65°C (149°F – 150 is close enough). When drying DO NOT use a normal oven – temperatures swing too radically in a normal oven and you’ll ruin the filament. (I use a counter-top toaster-oven that has a food-dehydrator settings … but my oven is able to control temps to within 1°C of the temperature I set – few ovens can do this.)

PLA doesn’t have a reputation for absorbing water like some other filaments. You could leave it out for a year and it would not likely be a problem. So this makes me wonder “what else” might be wrong (without having a photo to inspect).

As @Wrathernaut mentions … it could be under-extrusion.

You MUST use 2.85mm (sometimes referred to as 3mm) filament. The majority of filaments on the market are 1.75mm. While the filament will “fit” into the extruder … it’s too small and this will result in a few problems. It doesn’t fill the filament path in the hot-end and that can result in pooling. But the slicer calculates the rate at which filament needs to feed through to extruder the correct volume. Since 1.75mm is thinner … you’ll get FAR less volume than required.

If you are using 2.85mm filament then check that the tension is correct on the extruder. This is described here in step 10: Center the Idler Nut in the Adjustment Window

I’ve circled it here (this the left-extruder but there is a knob for both left and right extruders).

As you adjust the tension knob, you’ll notice the nut sliding in that window. This adjust the sprint-tension that helps grip the filament in the extruder gear. If it is too loose (nut is closest to the adjustment knob) then the filament isn’t being gripped well enough. If it is too tight (not is farthest from the adjustment knob) it can cut into the filament too hard and when doing retractions it will tend to grind up the filament (and can result in a jam).

You might also have a bad E-steps setting. E-steps (short for “Extruder steps”) is the number of stepper motor steps needed to advance 1mm worth of cold filament. This setting is set on the printer (not a setting on the slicer software). On the graphical control panel of the printer it is under:

Menu -> Advanced Settings... -> Steps/mm

The value for the Extruder (E-steps) should be a value close to 420 steps/mm. That’s the factory default. Often a printer will be tuned by testing this value. You can test it by using a sharpie to make a mark exactly 100mm above the extruder (where the filament enters the top of the extruder) … then (with print-head heated up to print temperature) tell it to extrude 100mm worth of filament. THEN compare the mark you made has moved 100mm. If it moved too far then the E-steps need to be reduced. If it didn’t advance enough filament then the E-steps need to be increased. We can help point you to the process of doing this test if needed. For now just see if the E-steps are set to 420 steps/mm – or at least some value pretty close to 420.

sorry for the late response but here is a picture of the low quality print in question! hope this helps some, will definitely apply the steps you all have mentioned!

Image 2 since Im apparanetly limited to 1 at a time will also check over the printers settings and check back

Definitely looks like it’s greatly underextruding. Verify that it’s slicing for 1.75mm vs 2.85mm filament, that the tension is fine (no filament stripping, and no missing steps) and verify your extruder steps/mm.

I think I found the issue, it’s been slicing for 2.85 while we’re using 1.75 the issue is that every time I go to change the material settings for the Verbatim PLA (a custom duplicate) it reverts back to the settings for 2.85 is there some save button I’m missing?

addendum: steps are fine and tension is fine

Assuming that you are using Cura LE, I think that this is a change that needs to be made in the printer settings. Do you know which nozzle you are using? Each nozzle is meant to be used with a specific filament diameter. It looks like the current Pro S comes with a M175 that uses 1.75mm filament, but the Pro comes with a 2.85mm dual extrusion head.

I also found this article on the lulzbot site.

If you’re using Cura LE, if you’re choosing the correct toolhead, it should have the right filament diameter as part of the material profile.

If you’re using an otherwise 2.85mm toolhead to push 1.75mm filament, change the Diameter of the Material in the profile to 1.75mm, click the downward arrow next to the profile name and Update profile with current settings/overrides.

image

using a m175 .5mm nozzle (i think if its the number printed on the nozzle)

trying it with the hard updated material settings will send pictures when the print is finished

I want to confirm your slicer settings. If you go to Settings>Printer>Manage Printer, you should get a page like the one below. Send a screenshot of it.