Slight blackening on the rear axis

[rotorhead 1]

Hi, I've had my UM2 for about 5 months and ran about 0.7kg of material though there so far so not a massive amount of use and have noticed a slight blackening on the rear horizontal axis. It does not seem to come off just by rubbing it but I have read the these rods are coated so have been reluctant to do anything else to try and remove it.

The only thing I have done to the rod is a couple of drops of light sewing machine oil just once a few days ago. In fact that was when I noticed it was starting to go a little black. The printer is used in a relatively clean office and is covered over when not in use.

anyone any ideas what it might be? If it matters? And how to get rid if necessary?

The photo perhaps make it look slightly worse than it is to be honest.

[model_dude 1]

I have also just noticed this on our UM2, but on the side axis rails (y-axis?) - especially the rail on the left as you look at the front of the printer (see pic below). There is some wear on the opposite side rail but not as bad. It does not rub off and looks to me like the markings you might get if metal has been rubbing on metal? Looks dark in this pic but at another angle it might look more silvery. There is no sign of this wear on the front and rear rails, nor on the rods for the print head. I have also routinely lubricated the rails/rods with sewing machine oil.

I am wondering if this might be due to a bad linear bearing? There is also a slight screeching sound that seems to correlate to the markings on the rail but I can't pinpoint the sound 100% to that particular spot, or whether it is coming from the pulley area near the back left corner (but which still correlates to the markings on the rail if you understand what I mean).

Edited November 11, 2015 by Guest

[Labern 774]

They need a regular lube with a drop of sewing machine oil.

To clean them dampen a cloth with oil and rub them, then move the head around and rub them again. Continue this till most of the gunk is removed. it should clean most of it up. The outer side rails have Bushes not bearings. so its good to give them a good clean every so often.

[rotorhead 1]

They need a regular lube with a drop of sewing machine oil.

To clean them dampen a cloth with oil and rub them, then move the head around and rub them again. Continue this till most of the gunk is removed. it should clean most of it up. The outer side rails have Bushes not bearings. so its good to give them a good clean every so often.

 

Thanks for the info, I gave the rail a really good clean with a clean rag and some oil but it did not seem to make any difference. I can't feel any damage on the surface but can't help but wonder if that's what it is. It's odd how it's only that rear rail that shows any sign, all the others are OK. I have lubed it up and I suppose will continue using it and monitor to see if it changes.

thanks again

[Labern 774]

Its probably just blackened the high spots on the shaft. bronze bushes tend to blacken shafts. I wouldn't worry to much as long as it moves freely. This happens to pneumatic cylinders and at work we have ones with 10's of millions of cycles that still run fine. If you see a scratch marks or de-lamination then there is concern to replace it and the bush.