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Alex
 Alex
(@al3x)
Active Member
black residue causing binding on x-axis smooth rods

I have had my new (and only) prusa MK3S + MMU2S  for about two weeks now. Having printed around a kilo of filament so far i have started to get black residue on the smooth rods. As per the user manual and forums, i wiped this off and continued printing. I have now started to get black plastic like flakes (maybe the bearing seal?) which then led to binding on the x-axis (would fail to home and would report a crash when one has not occurred). I seem to be back up and running after cleaning the rods and re lubricating with high performance bearing grease.

 

Two questions:

1. Any one else experience the issue with black plastic deposits on the smooth rods?

2. If so, was this terminal for the bearings or did re-greasing solve your issue longer term?

 

Thanks in advance

Best Answer by --:

Lack of grease in the bearings causes the nitrile grease seals to wear prematurely. This leaves a black smear on the rods. Pretty soon your bearings will start seizing.  Apply a few drops of a light machine oil on the rods try to work it into the bearings - keep them lubed until you get a chance to properly pack the bearings with suitable grease (e.g., lithese, lubriplate, superlube).

If the seals are flaking, your bearings are very dry and need immediate attention, and the seals are probably already damaged.  Contact Prusa and tell them what's happening.  It's their fault they tell customers the bearings come prelubed: but aren't.

 

Posted : 28/10/2019 6:53 pm
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(@)
Illustrious Member
RE: black residue causing binding on x-axis smooth rods

Lack of grease in the bearings causes the nitrile grease seals to wear prematurely. This leaves a black smear on the rods. Pretty soon your bearings will start seizing.  Apply a few drops of a light machine oil on the rods try to work it into the bearings - keep them lubed until you get a chance to properly pack the bearings with suitable grease (e.g., lithese, lubriplate, superlube).

If the seals are flaking, your bearings are very dry and need immediate attention, and the seals are probably already damaged.  Contact Prusa and tell them what's happening.  It's their fault they tell customers the bearings come prelubed: but aren't.

 

Posted : 28/10/2019 11:35 pm
Alex
 Alex
(@al3x)
Active Member
Topic starter answered:
RE: black residue causing binding on x-axis smooth rods

thank you for the response, very helpful.

I have already applied some lithium bearing grease, i think i will pull the bearings apart over the weekend, if the seals are damaged i have some replacements spare that look much better quality rather than getting replacements that will just have the same problem.

Thanks again for the heads up

Posted : 31/10/2019 5:48 pm
Joe
 Joe
(@joe-10)
Active Member
RE: black residue causing binding on x-axis smooth rods

Thank you for sharing this post. 

 

I recently had a failed print and noticed that the extruder wouldn't move past a certain part on the smooth rod.  Upon inspection, I found a clear sticky grease-like substance on it.  I cleaned it off and lubricated the rods, and now I'm seeing black residue.  It definitely some sort of oil, as I've wiped it off and its easy enough to tell.  Prusa support told me it was "basically dust from the rods" and I didn't quite agree. 

The attached pic is what I saw ~5 minutes after starting a print after cleaning the rods.  

 

 

Posted : 13/05/2020 3:22 pm
Alex
 Alex
(@al3x)
Active Member
Topic starter answered:
RE: black residue causing binding on x-axis smooth rods

@jrob

To be honest, i mostly forgot about this thread. After a while i had the bearing grind a groove into the smooth rod, according to Prusa support it is common for people to overtighten the bolts at the back of the x carriage assembly causing the bearing to seize - they were unable to provide a suitable torque range for the bolts which is a shame.

A little bit of blackened grease is normal over time for all sorts of bearings in my experience, yours picture doesn't appear to be abnormal, i just wipe off from time to time and apply a thin coat of bearing grease on the rods. Looking at my rods i am also getting a build up just like yours - also have it on my other printer and have seen it on car bearings and bicycle bearings too. If i were you i wouldn't be worried, though it wouldn't be a bad idea to ensure the x-carriage bolts are not too tight (although what too tight is, is anyone guess!)

Posted : 14/05/2020 5:59 pm
Agkirk
(@agkirk)
Trusted Member
RE: black residue causing binding on x-axis smooth rods

I also had the same experience with the black residue after light oiling 6 weeks back.  New Mk3S in March and 'crash detected' issue.  I continue to wipe the residue off and add a drop of synthetic light machine each week just to insure some gets to the bearings.  I see the residue on the Y-axis also but not apparent on the Z-axis rods, yet. 

Didn't have a good experience with Prusa Support team i.e. extremely slow response and appeared to not know about the bearings lacking initial grease/oil.

Posted : 15/05/2020 6:08 pm
Don
 Don
(@don-2)
Active Member
RE: black residue causing binding on x-axis smooth rods

I have been running for 3 weeks now and see black residue on my X axis rod. 

I am wiping and greasing, if I see flakes or rod wear, I would want to upgrade to something better. 

What is the conventional wisdom on 'upgrading' a Prusa in terms of rods bearing or ???

 

Posted : 17/07/2020 7:15 pm
Alex
 Alex
(@al3x)
Active Member
Topic starter answered:
RE: black residue causing binding on x-axis smooth rods

@donjanaray

You shouldn't need a large amount of grease, i aim for the thinnest even coat - even then i only re-apply once a year or so.

Flakes would most likely be from the bearing seals disintegrating and in itself not something i would be overly concerned with (see tim-m30's post above).

I think the prusa rods are probably okay as is (had no issues since), with the bearings perhaps benefiting from a better version (but only if they have already gone bad). If i need to replace the bearings again i would probably look at the misumi bearings.

Posted : 18/07/2020 5:43 pm
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