Strange Artifact (Possible under extrusion)

extrusion_issues tevo_tornado

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I'm running into a problem I can't solve. I'm having under-extrusion on some layers. These appear to be the exact same layer across all parts. In the photos I've included, you can see several rather bad layers, but towards the bottom there's on that lines up with another piece printed at the same time (Second photo).

This looks like under extrusion, but I checked my steps/mm on the extruder, and it was dead on. I'm not sure it's heat-creep, because I've printed some tall things, and at no point has it stopped or gotten really patchy, even.

I really want to get this figured out because it's the last big artifact I'm dealing with after putting a set of smoothers on, and upping the y axis vRef to 0.95v.

I had the same problem with some layers in the same spot. I found that one of the rollers on the z was bad with a flat spot on it. Switched it out and problem solved.

I have another possible explanation... I was getting a similar issue when I first got the printer, and noticed (after a while) that the wires going from the extruder and x-axis were occasionally getting caught on the bed. This caused a momentary shift in the print. When I zip-tied the wires and re-org'd, the issue went away.

I think that re-lubing the z-rod is a good idea too.

I've noticed the issues with the wire myself. If this printer has one design flaw, it's the cable management. I'm going to be redoing all the cabling to the z-axis this weekend; bought some connectors off Amazon, so I can make extension cables.

I had the same Problem when i printed my first bigger Parts. I did what Coat has wirtten - i using a special grease. After that move your x-Parrt 5-6 Times to the z-max and back to zero. After that the my Print was OK.

This seems to have done it! I cleaned the rod, and put some Super Lube on it, and so far the problem seems solved. I haven't reprinted those parts from the photo, though; I will try that this weekend, and make sure it's improved.

I'm not sure it is your problem, but it seems to solve the same problem at my printer. Clean the Z-rod and put on some new grease.

What is recommended to clean the Z rod? I am going to try a dry-lube, that leaves behind silicone. It came highly recommended, but I can't remember the name of it right now... I will obviously wipe it down with a lint-free cloth, but my though is that I should remove any of the existing grease/gunk with a de-greaser before I apply something else... rubbing alcohol? wd-40? something else? I don't want to leave any residue behind and have a squeaky-clean rod, before I apply new lube... Right? Or just wipe and lube?

What kind of grease should I use?

Update: The lubricant I applied is called "Tri-flow", but I haven't tested it yet... I'm installing extension cables this evening and will fire it up after to see if this stuff is any good. I'm not sure if it is a "grease", but the rod is silky smooth right now and virtually no resistance, due to a very thin layer of silicone left behind

I used the grease that came with another printer. No further specification on the tube than "grease".
But according to the internet you need synthetic grease with Ptfe (Super Lube for example).

Super Lube worked great, and is super cheap on Amazon.

I'm also getting under/over extrusion at the same layer... Let me know if you find a solution.

Cleaning and then re-lubing the rod seems to have fixed it. I'm going to do more testing this weekend, but I'd definitely recommend you start there.

It worked, just cleaned and inspected the entire rod and prints came out smooth. What kind of grease or oil did you use?

I used Super Lube: http://a.co/d/ic9sG5T, since someone else suggested it. That one tube will probably outlast the printer.