Bearings  

Re: Bearings

Nice vid and bearings. Are you replacing just the X axis ? or all?

Reason for replacing?

Re: Bearings

I had replaced some of the bearings on my MK2 just to try to cut down on noise, vibration and increase print quality. I have some extras left over (never replaced the Z axis bearings), plus I'll salvage the ones from my MK2 for the upgrade. It was good of Prusa to include bearings and rods with the upgrade though - the bearings can be damaged on removal and the old rods were rather soft.

Re: Bearings

Sweet, just decided to get a set of 10 of these on order today before seeing this. I too experienced the grindy bearings and replaced them with IGUS I had on hand. The IGUS were an improvement over a fouled bearing, but I don't think they are optimum.

What are you guys' opinion on packing them with grease?

Re: Bearings

This is so timely! My MK3 printed one thing and a bearing went out. I will be getting some of these.

Re: Bearings

If possible can you make a before and after video to compare noise? That is the one thing I have found is the rods and bearings are very noisy.

Re: Bearings

Regarding lubrication, the Prusa bearings have some oil in them but not a whole lot.
The MISUMI bearings are filled and coated with what seems to be an appropriate amount of machine oil (a good amount, but not too much). When you put them on the rod and start moving them up and down the rod and bearing are fully lubricated - no need to oil them.

I don't think the noise difference is significant enough to notice, at least not on the MK2. The stepper motor vibration more than overwhelms the bearing noise. It may be on the MK3, but I'm certainly not going to do a full build then disassemble it, then reassemble it 🙂 Too many competing things in life I need to do. Sorry.

However when you put them on the rail and feel them move, that's when you really notice the difference. The MISUMI are like butter but the Prusa can be quite crunchy/sticky.

HOWEVER... Does it actually matter in real life printing? I don't know. Maybe it doesn't matter because the friction difference is totally irrelevant to the steppers doing the movement. The MISUMI bearings are also quite a bit more expensive than the ones Prusa uses. If it doesn't actually make a difference, and the Prusa ones are cheaper to use, then they would actually be the better choice, logically speaking. However, I like smooth things, not crunchy things, so that trumps logic here. 😀

Re: Bearings

Regarding lubrication, the Prusa bearings have some oil in them but not a whole lot.
The MISUMI bearings are filled and coated with what seems to be an appropriate amount of machine oil (a good amount, but not too much). When you put them on the rod and start moving them up and down the rod and bearing are fully lubricated - no need to oil them.

That oil that ships in the MISUMI bearings...it's not for lubrication, it's merely for packaging, to protect them during shipping and long-term storage.

Read up on their website. They recommend removing the oil with a degreasing agent, then replacing it with light grease. I swizzled mine around in a plastic pail with some engine degreaser, lightly tapped out the remaining liquid, then let them air dry (and repeated that whole process once more). I use white lithium grease in a spray can with long nozzle, which makes it easy to shoot it directly into the bearing tracks before you insert the rods.

Re: Bearings

Regarding lubrication, the Prusa bearings have some oil in them but not a whole lot.
The MISUMI bearings are filled and coated with what seems to be an appropriate amount of machine oil (a good amount, but not too much). When you put them on the rod and start moving them up and down the rod and bearing are fully lubricated - no need to oil them.

That oil that ships in the MISUMI bearings...it's not for lubrication, it's merely for packaging, to protect them during shipping and long-term storage.

Read up on their website. They recommend removing the oil with a degreasing agent, then replacing it with light grease. I swizzled mine around in a plastic pail with some engine degreaser, lightly tapped out the remaining liquid, then let them air dry (and repeated that whole process once more). I use white lithium grease in a spray can with long nozzle, which makes it easy to shoot it directly into the bearing tracks before you insert the rods.

Freaking awesome bit of info there, I would have installed mine just assuming it was normal lubricant. Thanks!

Re: Bearings

Got my 10 Misumi LMU-N8's in. Perfect fit. Degreased as advised and hit them with PTFE while installing, and they move on the rod just by tilting it back and forth. The interesting part is, they do this with zero play. My Y axis bed twist went from about 2-3mm to none, rock solid.

Huuuuuuge improvement over stock or IGUS. 🙂

Re: Bearings

i use slot car lubrication oil.
i wash my hands, oil my finger tips then coat the polished rods with the oil from my finger tips. it allows you to work it to an even light coating. you don't want to get too much oil on the rods as the bearings will push off heavy oil and it can fall on the bed while printing causing contamination.

Re: Bearings

Are they quieter though?

Re: Bearings

I got the Misumi LMU8's and their PSFJ8 linear rods when I did the Haribo upgrade. They are very smooth and quiet. Probably not worth the cost for most people, but I had to get different length rods for Haribo anyway so I went all out. Could just be because I got the settings dialed in better, but I think my prints' edges look better since i did the upgrade. I think most of the noise comes from the steppers now during fast movements.

Re: Bearings

Got my 10 Misumi LMU-N8's in. Perfect fit. Degreased as advised and hit them with PTFE while installing, and they move on the rod just by tilting it back and forth. The interesting part is, they do this with zero play. My Y axis bed twist went from about 2-3mm to none, rock solid.

Huuuuuuge improvement over stock or IGUS. 🙂

So, how are they? Where did you notice differences while printing (noise, print quality, etc)? Any increase in false collision detection? I'm very interested in swapping bearings - after my first inevitable tear-down.

Thanks,

-Dan

Re: Bearings

Got my 10 Misumi LMU-N8's in. Perfect fit. Degreased as advised and hit them with PTFE while installing, and they move on the rod just by tilting it back and forth. The interesting part is, they do this with zero play. My Y axis bed twist went from about 2-3mm to none, rock solid.

Huuuuuuge improvement over stock or IGUS. 🙂

So, how are they? Where did you notice differences while printing (noise, print quality, etc)? Any increase in false collision detection? I'm very interested in swapping bearings - after my first inevitable tear-down.

Thanks,

-Dan

In my experience they may be a little quieter, not much though. Biggest improvement was reduction of Z twist in the bed, it has zero twist now but still glides to the touch when the belt is off. The IGUS I had previously worked well enough but the bed had about 3mm of Z twist if you tugged on a corner. When cleaned properly and lubed up with PTFE, these things absolutely destroy everything else I have tried smoothness wise. I can't help but think that the reduction in Z twist on the bed and easier moving bearings translates into better prints. The reduced friction likely helps with collision detection as well, but I haven't had that on since a week or two of having the MK3. 🙂

I wish I had more details about print quality, but pretty much all I print on my MK3 these days is hollow cubes. That extrusion inconsistency bug is making me too irritated to print anything else.

Re: Bearings

Brigandier,

Thanks for the feedback about your experiences with these bearings. I'm on the fence about buying them now before my first MK3 build or waiting until I need them (probably, the latter). I'm not expecting any miracles from them, but I do see it as a good piece of mind purchase. Regarding the extrusion behavior - I hear ya! I watch these Pinda calibration, bed leveling, and extrusion threads with great interest! With the dedication of all you guys/gals on the forums, I'm hopeful for the MK3.

Thanks,

-Dan

Re: Bearings

Where does one find these improved bearings, and how much do they cost?

Re: Bearings

Where does one find these improved bearings, and how much do they cost?

https://us.misumi-ec.com/vona2/detail/110300026540/?HissuCode=LMU-N8

Re: Bearings

1. Are you guys also replacing the rods? Found a few other posts like: https://shop.prusa3d.com/forum/improvements-f14/misumi-replacement-rods-and-bearings-t3906.html . Seem like Misumi engineers recommend sealed bearings for 3d printing so they say to use LMU8 instead of LMUN8. They also recommend G6 tolerance rods (if you are replacing them too). Not sure the size of the rods we should replace them with, though.

2. What are you guys using for de-greasing the antirust oil? Do you have a link to what you got?

3. Would it be fine to use this White Lithium Grease https://www.amazon.com/gp/product/B004X70LZA/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1 after removing the antirust oil?

Thanks

Re: Bearings

@gaston.d3

I had to replace two of my rods for the Haribo mod (Y rods are longer for Haribo), so I figured I might as well replace them all since my Mk2S didn't have the induction hardened ones. I used Misumi part number PSFJ8-<length> for my rods (ex: PSFJ8-370). They are induction hardened bearing steel with a hard chrome surface finish and G6 tolerance. The bearings do work well on the smooth rods provided by Prusa, I accidentally used the original Z rods instead of my new ones and only noticed when I was cleaning up and found the Misumi rods still in their bag. 🙄

My answers to #2 and #3 Here.