This topic contains 14 replies, has 7 voices, and was last updated by 
Simon 2 years, 4 months ago.
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when the head is moving down, left part of the z axis is stuck and has a sound like cracking. how can I solve this issue?
video: https://www.youtube.com/watch?v=E5WtXUhjUHs
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This topic was modified 2 years, 4 months ago by
davit.
This has happened to me a few times, and I suspect others.
The drive rod has a very fine thread, often this will fill with fine debris and dust and impede the passage of the two captive nuts on the gantry bracket.First approach is to raise a ticket and get the support team to offer advice. Taking the covers off can invalidate the warranty unless you’re working under direction!
However, I have in the past taken the cover off and cleaned the threads with Isopropyl alcohol and a toothbrush to remove the muck, then reassembled. Make sure to mask any components with kitchen paper or paper to avoid getting isopropyl on them.
This does require a degree of mechanical ability though and best to take photos if you attempt to completely disassemble the components, remove the stepper motor and clean if you want to avoid the embarrassment of reassembling the parts and putting one in upside down! (Yes, I did this).
Don’t keep moving the carriage up and down as I’m pretty convinced that my printer cross threaded itself when the carriage got stuck and the gantry went badly out of level. I had to replace the stepper motor assembly.
By the way, this is another reason I only lubricate with dry lube PTFE spray, not oil. I’m trying to see if the PTFE will resist attracting dirt and debris better than a thin film of oil does.
I had terrible issues with the original oil. It has been like an odyssey. I had increasing problems with the Z axis, and I tried to cure them with cleaning and applying some drops of the original oil, but the more I added the worse things were going (!). After painful, long, careful cleanup of remains of the original oil (a white powder, something you wouldn’t expect to find) things went OK without any oil at all but it was just a test and I had to lubricate it. So I applied the original oil and after a bit the threads jammed again. So I cleaned everything again, a very long and painful process, and decided to use the most logical type of oil I would use there: machine oil. Things went much better, no jam at all. Then I thought the cause of the jam may have been a different one than the recommended, original oil, and again I cleaned up the threads carefully (it was much easier after machine oil), till it was bare metal, so I applied again the original oil. The threads jammed again.. I said no this can’t be real. I cleaned everything and used machine oil. All went smooth. Then one day I had to verify for a LAST time the original oil (I was curious like a monkey), and it jammed again. I could be heard swearing, I cleaned everything FOR THE LAST TIME but meanwhile I bought a very high quality PTFE grease (one used for guns, the best I could find worldwide, it’s German stuff). I applied it and since then no more Z axis jam, whistle (which I could hear before a jam), or any other problem. +1, no, +1000 for PTFE also IMHO.
Then I’ve read around on the UM forums and other forums, and it’s general consensus (also from the manufacturers) that machine oil is good for threads, but PTFE is the best of all.
I really really really do not understand where’s the need to use synthetic, high temperature oil (the original one) for the Robox threads. Maybe the one that came with my Robox was out of specs (it leaves a white powder after drying) but even if it was just mine, again, what is the purpose to use synthetic high temperature oil for the Robox Z threads?
Does it even get warm? Is it the cylinder wall of a model airplane?
Use PTFE or, if you don’t have it (get it..), machine oil. You can’t go wrong.
This is what I use:
@dmullerdesign @omega64 thanks for the answer. it seems I have fixed the issue by taking the cover and cleaning + lubricating the axis, now it works without any horrible sound.
Just be wary it may reappear to bite you. Those threads, as @Omega and I have discovered, are a royal pain in the rear to clean properly. It took me ages with a toothbrush and isopropyl to clean them the first time round and then I lubricated with the supplied oil and they lasted for a while before jamming up again. Hence why I am only trying the PTFE stuff for the moment.
Just keep an ear out for that horrible noise in case it happens again!
Wow. Lots of thread issues! I haven’t had to clean or really touch my threads at all on any of my three printers. I used white lithium grease instead of oil after hearing about @omega64 and his thread issues. I don’t get a lot of debris in my printers either, probably because I wipe them out on a regular basis and take a small vacuum and clean out the print area from time to time.
I operate two Betas and four Production Robox.
I am the US/Canada Technical Support engineer for the Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/benWhite lithium grease is very good too, PTFE is only slightly superior to it, but lithium grease is perfect for the purpose as well.
Of course the first and foremost thing to do is to avoid debris/dirt getting into the very fine threads, but in my former case (perhaps the original oil supplied with my Robox was defective, I don’t know why it was so bad on me) the oil was drying leaving a white powder which was the cause of the jam, so no amount of “avoiding dirt to go there” would help anyway, once the oil dried.
With the proper lubrication, my Robox’s Z axis work wonderfully, no strange noise no “whistle” sound that I had learned was the precursor of a jam (with some missed steps inbetween).
I have never either had to clean and re-apply the PTFE grease since then, it works too good and it still looks very clean.
I’ve had massive z-axis thread issues since day one as a beta backer. The first ever thing my machine did was to throw the gantry way out of alignment when trying a calibration.
As with other forumers above, diligent work with a toothbrush, isoprop alcohol, and a WD40 soaked cloth (advice from CEL) is useful to get the rods clean. I’ve had nuts jam on the threaded rod so tightly that I could only remove them with pliers and a wrench.
I’ve had it so bad in fact, that I have quite the collection of steppers with ruined threaded rods which CEL have covered under warranty. I’ve asked before about their supplier for the steppers so that I could just buy spares, but unfortunately CEL do not wish to divulge that information.
I for one am quite curious about why this happens to me so frequently, and it always happens to the threaded rod on the filament side, which is enclosed. You’d expect it to happen more with the other threaded rod, which is fully exposed.
Anyhow, I’ve been using sewing machine oil and it seems to work well. Have been waiting for the oil to run out before trying PTFE, but in light of the solid recommendations above, I might just go with it instead.
Yup, “sewing machine oil” is just the “machine oil” I mentioned before, I’m not a native English speaker so I may have used the wrong word (although, probably, both are correct).
Perhaps we were the unlucky receivers of a batch of defective original oil, but still I really don’t understand where’s the need to use synthetic high temperature oil on the Z threads, regardless if my batch of oil was defective or not. Those threads barely move on each +1 layer, and with not so much load.. the oil should be chosen to emphasize other characteristics (it’s always a trade-off, you either want performance in a sense or in another one, that’s why many different types of lubricants exist) than its high temperature resistance under heavy load, as you would for example in a aircraft model 2 stroke engine, where synthetic high temperature oil is a must. But it runs on extremely different conditions than a 3D printer’s Z axis thread.
I actually think that the oil is not intended for the threads at all and only for the rods. And the reason that it is high temp synthetic is because of the relatively high temperatures of the ABS printing environment. The oil doesn’t seem to evaporate and doesn’t smell detectably when printing ABS. If you have a residue, I think yes, you may have a contaminated batch of oil, but that is just my opinion.
I operate two Betas and four Production Robox.
I am the US/Canada Technical Support engineer for the Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben@omega64 Yes, always the filament side for me too…how odd. Makes me think that something else is at work (fine debris from extruder?). The atmosphere is quite dusty. I live on a farming estate and the ground here is boulder clay. Went wet it’s sticky, when dry it turns into a fine dust that gets everywhere. I run a 3m Filtrete in the office 90% of the time but it there is always a fine layer of dust on everything after a while.
Having two dogs doesn’t help either!
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