Replacing Bearings on X axis, what tips and tricks should I know?
I have new bearings coming in for the X axis because mine started squeaking. They are from VXB, I went ahead and purchased the kit of 12 so I have spares or if I feel the need to replace the others later. The Wholesale Lot 12 LM8UU Linear Bearing for 3D Printer Prusa.
Is there anything I need to do before installing them (other than remove the old ones and clean the rods)? I will inspect the rods closely for damage, but moving the head fully left and right I could not see any damage, so I am confident they are good. But still, a second look costs nothing...
So the bearings come in the mail, I open them and inspect them. Assuming they are good, what next? Do they come with a shipping oil I need to remove? Do I need to grease them before use?
RE: Replacing Bearings on X axis, what tips and tricks should I know?
Prusa manual you can see how to install.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
Prusa manual you can see how to install.
I'm interested in the things that crunching Emmanuel. I've read in some places that you need to clean the bearings and then grease them before use, but the manual mention nothing about this.
Looking for things like that, things were supposed to do but the manual doesn't tell us we're supposed to do. If such things exist.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
The Prusa manual is right. There is one thing the Prusa manual doesn't say, though:
The base oil provided with the bearings is not intended for lubrication, but rather for rust prevention. While it will work for a while (months?), it's certainly a good idea to replace it with a more long-term lubricant.
It's good to grease the bearings with a lithium soap grease, ideally NLGI ("grade" or "number") 0, 00, or 000, but NLGI 2 (more common in stores) will do, too. With NLGI 0 and below, you can simply pack the bearings full of the grease, with NLGI 2 you need to be a bit more careful not to overdo it, as it is more viscous and if there is too much, it'll prevent the balls from rolling.
Most preserving oils are compatible with lithium greases and don't require removing before applying this kind of grease. You can wash the bearings with kerosene and isopropyl alcohol if you like, but it'll be just fine without a wash.
A very popular option is also SuperLube 21030 (also compatible with the preservative oil), which is a good synthetic lubricant, however contains PTFE powder. The use of PTFE powder for linear bearings is controversial. It may improve the smoothness of low-cost bearings by providing extra cushioning between the rolling surfaces, but may also help sliding rather than rolling, possibly causing scoring of the rods. YMMV.
When applying grease, make sure the rods are also covered with a thin film and don't show any dry spots.
That's it.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
A grease recommended by Misumi is White Lithium Grade 2 ... tubes branded Lucas Oil can be found at Home depot (in the US). I use synthetic Superlube with PTFE, also a Grade 2 grease. I haven't found the PTFE to be an issue. Misumi also says plain old motor oil is okay in a pinch.
Main point here is ANYTHING is better than no lubrication. Grease is probably best because it stays on longer, but a bit messy.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
Thank you all!
RE: Replacing Bearings on X axis, what tips and tricks should I know?
I recently followed this guide regarding cleaning/greasing your bearings. One thing I was quite surprised by, was the part where it came to sliding the bearings up and down each 8mm rod to grease them up. Almost every bearing was great (they were all still new) however 1 or 2 for want of a better word "dragged" a bit more on the rods than others.
Those two went to either end on the Z axis (I didn't have any better spares). Didn't think I would be able to tell but once you've done it with 10 bearings you get an idea of what a crap one is.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
I'm not an advocate of grease for 3d printers but rather oil.
Grease is basically an emulsion of some form of carrier which holds the oil and can be Lithium soap : https://wd40.co.uk/diy-and-hobby/high-performance-white-lithium-grease-overview-uses/ (All applications seem a bit heavy duty compared to a printer!)
calcium soap, clay (yes you did read that correctly, and you would not want to put this into your printer) or many different compounds.
To release the oil either extreme pressure is needed (Which creates heat), or just heat. Both things you don't usually see in a 3d printer.
Also there is such a thing as over greasing, on a recirculating bearing like the linear bearings are, it causes churning and the ball bearings to stick and rather than roll on the rod, they slide.
Plain oil will have a capillary tendency and will coat the individual balls and the channels and rods with a thin film, and if you over oil, you will just leave an oily mess on your printer.
Yes, you have to oil more often, but a quick wipe of the rods to give them a clean of any dust, a drop or two of oil, run the bearings backwards and forwards over the oil and your good to go.
A good oil dispenser pen will last you months with one fill and good old singer sewing machine oil is good enough. It's been lubricating the moving parts of sewing machines for far longer than any of us have been around and look at the speed those things can move at!, and no ball bearings either, just a bush.
What I did when I first assembled my printer is to clean the excess shipping lubricant out, then literally flood the bearings with sewing machine oil and allow excess to run out, just stand on paper towel for an hour, then assembled the printer.
It runs smooth and quiet and I oil it when I clean the rods because dust build up leaves in effect a tide mark where the bearings stop on the shafts., Just one drop each side of the bearing then move the bearing over the oil and back again over the other drop on the other side, just watch you don't put too much oil on as it can drip.
It's like you wouldn't grease a swiss clock movement, but you would apply a drop of oil judiciously where needed.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
I'm not an advocate of grease for 3d printers but rather oil.
Grease is basically an emulsion of some form of carrier which holds the oil and can be Lithium soap : https://wd40.co.uk/diy-and-hobby/high-performance-white-lithium-grease-overview-uses/ (All applications seem a bit heavy duty compared to a printer!)
This one is not an appropriate grease for printers AT ALL. It's almost pure lithium soap, almost no oil in the mixture. After drying, it has the consistency of spread cheese. Way too viscous for anything that's supposed to roll.
When choosing a grease, it can't be just any grease, even not any lithium grease.
calcium soap, clay (yes you did read that correctly, and you would not want to put this into your printer) or many different compounds.
For rolling bearings, only lithium-soap, aluminum-soap and a few special synthetic thickeners can be recommended. Certainly not silica clay.
To release the oil either extreme pressure is needed (Which creates heat), or just heat. Both things you don't usually see in a 3d printer.
The pressures (and shear stresses) at the point of contact of the ball are enough for the oil in the grease to do its job. In fact, even the capillary forces are enough for the base oil of the grease to spread over the surface, if the right grease is used.
Also there is such a thing as over greasing, on a recirculating bearing like the linear bearings are, it causes churning and the ball bearings to stick and rather than roll on the rod, they slide.
Yes, particularly with high-grade greases. The commonly recommended NLGI 2 grade is prone to over-greasing.
Plain oil will have a capillary tendency and will coat the individual balls and the channels and rods with a thin film, and if you over oil, you will just leave an oily mess on your printer.
With NLGI 000, I don't observe the issue, it'll just be pushed out the same as oil.
Yes, you have to oil more often, but a quick wipe of the rods to give them a clean of any dust, a drop or two of oil, run the bearings backwards and forwards over the oil and your good to go.
Yes, oil is much harder to make a mistake with. Most machine oils will work just fine, even higher viscosity oils (like car oils) will work OK with some limitations. Greases on the other hand ... there are many many different types and only some are appropriate.
A good oil dispenser pen will last you months with one fill and good old singer sewing machine oil is good enough. It's been lubricating the moving parts of sewing machines for far longer than any of us have been around and look at the speed those things can move at!, and no ball bearings either, just a bush.
What I did when I first assembled my printer is to clean the excess shipping lubricant out, then literally flood the bearings with sewing machine oil and allow excess to run out, just stand on paper towel for an hour, then assembled the printer.
It runs smooth and quiet and I oil it when I clean the rods because dust build up leaves in effect a tide mark where the bearings stop on the shafts., Just one drop each side of the bearing then move the bearing over the oil and back again over the other drop on the other side, just watch you don't put too much oil on as it can drip.
While oil is perfectly fine for linear bearings, I do prefer low-NLGI low-viscosity lithium grease, because even if put too much in, it will not seep into places where I definitely don't want it, like the inside of the extruder. Such a grease is mostly oil, almost liquid, but the small amount of soap prevents it from flowing and dripping.
It's like you wouldn't grease a swiss clock movement, but you would apply a drop of oil judiciously where needed.
You wouldn't use machine oil on a trailer hitch either. A 3D printer is neither a swiss clock, nor a trailer hitch. 😉
RE: Replacing Bearings on X axis, what tips and tricks should I know?
In the past people said lubrication is bad, and attracts dust that gets into the bearings. Go figure. A supplied silicone grease is the only lubricant for the Z screw on an Ultimaker 2+.
I am back and new with a Prusa MK3S kit build, so far so good but some issues appearing after 40 hours of printing and swapping materials.
On my Anet A8 build however, I used drylin Igus bearings in replacement for the supplied bearings, wonderful bearings, great prints on my Anet A8.
Nigel
Life is keeping interested and excited by knowledge and new things.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
I have used sewing machine oil in the past. I was lambasted for it. Go figure.
Nigel
Life is keeping interested and excited by knowledge and new things.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
Someone on one of the facebook groups said they talked to all the main bearing makers for our needs and they all said grease should be used instead of oil.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
This is one of those polarizing issues that people get up in arms about. I would say the reality of it is that so long as there is no evidence of damage or problems, use whatever works for you (e.g. what you already have on hand). I'd say crunchy bearings are by far a bigger offender for causing any sort of damage to rods than the type of lubricant used (within reason)... and so long as you do *something* to replace the shipping oil in your bearings a 3D printer is such a light load that you've significantly improved their lifespan if they were good to begin with.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
I've chatted at length with a Misumi engineer. He basically said #2 Lithium grease is the ideal grease, even for light loads. A #2 synthetic grease is also good, even if it contains PFTE. And, if nothing else is available, motor oil for car engines (his words).
Bottom line: Most anything is better than nothing.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
I have one tip that doesn't have to do with lubrication.....
When removing or installing the x-axis off machine, do it WITHOUT the trapezoidal nuts bolted into position. Instead support the x-axis on a pair of filament boxes. Unbolt the trapezoidal and spin the off independent of the x-axis. While trapezoidal are off, use some m3 bolts to temporarily hold the trapezoidal nuts in position. Installation is just reverse. Place x-axis onto Z-rods and lower to your support boxes. Remove temp M3's. Thread trapezoidal down and bolt into position.
This reduces risk of cross-threading the trapezoidal nuts - something all too often happening when one attempts to thread them by turning the z-screws while holding the entire x-axis with one hand. You can feel correct thread alignment a lot easier if the nuts are not bolted down.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
Adding to what Guy says: pretty sure the T-nuts and lead screws do not need lubrication. Generally, Delrin is self lubricating.
RE: Replacing Bearings on X axis, what tips and tricks should I know?
One more thing...
Mark on the outside of the LMU88's, with a permanent marker, the location of each row of bearings That make keeping rows properly aligned easy when you can no longer see the rows.