How do you take care of your linear bearings?
After a week-long break, my x-axis is seizing. I can hear and see it stick and moving the carriage manually is very difficult. I am not using any lubricant. It is a little dusty in the room, but not overly so. This printer only has less than 100 hours on it.
Is there something I can do to resurrect them? What can I do to prevent this in the future?
This is a MakerFarm Prusa I3 kit with LM8UU bearings.
Linear ball bushings are designed to run on hardened steel shafting . If not hardened shaft then that is all you are going to get. One thing that you can do is turn the shaft to provide a new bearing surface. You can get linear ball bushings w seals. Bob
Before I put mine on, I always lube them with white lithium grease. It’s also possible that if you used some lower quality bearings, that one (or more) of the balls popped out. There are also other bearing options out there, like brass sintered bushings, and IGUS also has some selection as well.
Interesting. I had assumed these were hardened, but now that I look, I can see indentations on the rods. I will give that a shot.
You can get hardened shaft at McMaster.
@Bob_Roth I’ve been using 17-4 PH stainless for a long while now without detriment. No grooves, no “case hardened steel”, no nickel plating, and no worrying about my rods corroding in the humidity.
LM8UUs need lubrication, they can’t simply be run dry on the rods.
I had a similar problem. I applied some CRC Multilube Gel to the ends of the bearings using the applicator tube. This fixed the problem. It soaks in well and then thickens up a bit. It does not seem to affect ABS, at least in the few months I have been using it. I apply some every few days of printing.
No bearing should run dry, at worst a little vegetable oil. Lithium grease is the best, some spray lube on the rods to get into the inner chamber of the bearing.
I have been designing and building industrial automation for 39 years. I built 2 machines for Bama Foods that stamp out 2.5 million biscuits a day 24/7 for 5 years that run on linear ball bushings. If I ran a linear ball bushing on a soft shaft my customers would run me out of town.
Thanks all for the information about lubrication. I had been warty because I know it can collect dust and make things worse. I will try some lube and rotate the shafts to avoid any grooves which I has created. Glad to know that I might not have to replace anything.
@Bob_Roth what would you recommend for low-maintenance rods then? Something that doesn’t have to be lubed every week, can be left in a garage environment (humid, damp at times), etc?
Plenty of Chinese suppliers provide induction hardened linear shafts, aside from occasion straightness issues, they’ve always served my purposes. Another option is coated aluminium shaft and ingus plastic bearings, the bearings liner wears our but replacement liners are cheap and can be swapped out without removing the bearing from the shaft.
Argh. I can feel grooves in one of the rods, with a visible pre-groove in a second one. There are two bearings which are clearly worse than the others, even after lubrication. I’m going to ask makerfarm to see if I can get replacement parts.
@Matt_Harrington if you’ve got scoring or Brinnelling, bin the assembly and start again. I’m surprised though, you must have got some bad contamination to screw them in only 100 hrs. I regularly run systems for 10,000 km tests and don’t get what you describe.
@Matt_Harrington , it sounds like you have 2 problems as you’ve observed. But I’m thinking that the scoring may have been caused by the seized bearings. AFAIK, makerfarm printers are decent design, so I figure they selected rods that should survive normal wear. A sized bearing would literally score, as in abrasively scratch a line into the rod. I’m skeptical that you’d have true brinelling as that is usually a single point divot caused by a shock. I could see a brinell growing into a larger divot, but I’m thinking you are correct in the description of scoring
@Tim_Rastall , it looks like I’m on the hook for replacement parts. Do you mind throwing me some links? I don follow all of the terminology and don’t want to get the wrk stuff. I figure I need at least two new bearings and rods. If one bearing has worn a groove in a rod, should I replace the other apparently functioning bearing on that same rod?
Replacement bearings should be pretty cheap, but the bearings should easily slide under their own gravity, this would be a good indication that they are free running
@Eric_Moy , I don’t think a single bearing in this kit slides under its own weight, lubricated or not.
I just moved my CNC, and spotted a few deposits on the rails, possible corrosion, managed to polish them out and re lubricate. Fingers crossed all ok, moving freely without play.
@Matt_Harrington , sheesh, that’s not good. What if you shoot some spray lubricant, like silicone spray lube? Bearings should already have oil in them though