Bearing quality? Swap for misumi  

Re: Bearing quality? Swap for misumi

I don't have a MK2 so I can't compare with it, but I would describe the X axis as always quiet, and the Y axis as medium-loud during high speed moves, and quiet during small or low speed Y moves. Compared to a Wanhao / Monoprice i3, the MK3 Y stepper noise (the "musical" noise) is MUCH quieter, but the noise from the Y axis bearings & rods is a bit louder. The MK3 is overall much louder than my 300mm^3 D-bot with linear rails and Trinamic drivers, but that is not a fair comparison. 🙂

Inside my small office, the MK3 is loud enough during fast Y moves that you have to talk over it. With the door closed you can still hear it. I realize that is highly subjective but I don't have a decibel meter.

I plan to wait a bit and see if anyone hears a noticeable improvement from using other bearings like Misumi.

Re: Bearing quality? Swap for misumi

Hi all,
Does anyone who has build their mk3 have any comments on the quality of bearings that are being used?
Has it improved since the mk2s or do you think they are the same quality?
I'm wondering if it is worth swapping out for misumi bearings on the first build as I have done on my mk2s's
Thanks

I bought some of the Misumi bearings and installed them on the Y axis of my MK2s. I was not impressed with the ones I recieved. One or two of the bearings make an odd clicking sound when the Y axis moved. Worried me to the point where I took them off and returned the original bearings.

Re: Bearing quality? Swap for misumi

This is an honest question. What's so special about the misumi bearings? Are they really the best quality bearings out there?

Re: Bearing quality? Swap for misumi

This is an honest question. What's so special about the misumi bearings? Are they really the best quality bearings out there?

Well they are the only ones you can order from a reputable brand.
I have them and to be honest I don't see/hear much difference.

Re: Bearing quality? Swap for misumi

The bearings are better on the MK3, this was stated in one of the MK3 videos on youtube where Mr.Prusa was being interviewed. He was asked why they did not use igus bearings, and he basically said there was no need the new bearings on the MK3 are really quiet and upgraded from the mk2. Judging from the videos, I am not going to replace the bearings with igus or misumi.

Re: Bearing quality? Swap for misumi

This is an honest question. What's so special about the misumi bearings? Are they really the best quality bearings out there?

Most linear ball bearings are no-name chinese products, and then there are Misumi and SKF bearings.
SKF is the most expensive and most likely the best quality , Misumi is the only other "brand bearing" I know of and it's a Japanese company with manufacturing in Vietnam which raises the quality expectations.

In general, obvious differences between the different bearings are the number of ball rows in the bearing and the ball sizes.

SKF LBBR8 has bigger balls and 4 rows, bigger diameter and need a holder to support the ball rails.
Misumi has the same form (LM8UU) and steel housing as the cheap chinese bearings, but 4 rows of balls and supposedly better quality.
Then there are also chinese bearings with 4 rows of balls, but the question is how to judge how good they are.

I have a set of those 4-row chinese bearings and matching hardened, low tolerance rods lying at home waiting for the MK3.
When I get the kit I will compare these rods and bearings with the kit parts and report.
Best case would be less slop and smoother running - the original Prusa rod/bearing combo seems to be a little loud.
But honestly - I don't think it's really necessary and I don't expect big improvements.

Re: Bearing quality? Swap for misumi

Thanks for all the input. I agree the latest videos on youtube + twitter do show it's really quiet already!
I had changed the original bearings in my MK2S as the supply ones marked and scored the rods really quickly, maybe I just got a bad set. Moving bearings by hand the misumi seemed much smoother than my mk2s bearings, but hopefully no need with the new mk3!

Re: Bearing quality? Swap for misumi

Which misumi pieces would be needed for a MK3?
i recon there are 6 rods with 3 different lengths and 9 bearings?

Re: Bearing quality? Swap for misumi

Which misumi pieces would be needed for a MK3?
i recon there are 6 rods with 3 different lengths and 9 bearings?

I think 10 bearings 🙂
I asked chat about the rod lengh:
z 320mm
y 330mm
x 370mm

Re: Bearing quality? Swap for misumi

I also wonder about using the long bearings for the z instead of a pair of the normal ones

https://uk.misumi-ec.com/vona2/detail/110302578040/?ProductCode=LMUW8

Re: Bearing quality? Swap for misumi

I just re-assembled my MK3 Y axis with the change of aligning the bearings so that one row rides on top of the rail, as was recently added to the build manual (and apparently was always part of the MK2 manual). This noticeably reduced the noise from the Y axis. Now I'm happy with the stock bearings.

Re: Bearing quality? Swap for misumi

I also wonder about using the long bearings for the z instead of a pair of the normal ones

https://uk.misumi-ec.com/vona2/detail/110302578040/?ProductCode=LMUW8

You could, I've done it on my Haribo MK2S.
But IMO it's a waste of money and time. The stock bearings are more than good enough for the Z axis.