LM8LUU bearing problem?

Discussion in 'Build Help' started by jdix, Apr 15, 2016.

  1. jdix

    jdix Member

    Joined:
    Dec 20, 2015
    Messages:
    6
    Likes Received:
    1
    Hi all

    Just going through building my printer and have got to the stage where I'm putting the single drive x-carrage on (http://wiki.e3d-online.com/wiki/Big...sembly_Process#Single_Direct-Drive_X-Carriage)

    One thing I have noticed though is that when moving the xcarriage around, one of the LM8LUU bearings attached to it seems to be making a kind of tick-tock noise.

    Is this something I should be concerned about at this stage? or have I done something I shouldn't, like overtightened something, or should it sort itself when I've put it all together and applied some lithium grease?

    Thanks for any help

    James
     
  2. Dr Jeep

    Dr Jeep Well-Known Member

    Joined:
    Sep 12, 2015
    Messages:
    530
    Likes Received:
    169
    They can be a bit rough sounding and feeling until lubricated and even then will always feel slightly sticky. I did find however on mine that it tightened up if I did the bearing caps up too tight so actually left them just beyond finger tight.
     
  3. Henry feldman

    Henry feldman Well-Known Member

    Joined:
    Sep 5, 2015
    Messages:
    969
    Likes Received:
    389
    So a whole bunch of us got defective bearings (the little balls had fallen out). A bunch of us bought third party (don't go cheap), I for instance got mine at ServoCity and they are very smooth. I actually looked into the originals with my borescope and you could see missing balls. There was no improvement in performance with Lithium grease (not surprising) so given how critical a component this is, just bought new ones. They weren't expensive.
     
  4. Alex Stevenson

    Alex Stevenson Well-Known Member

    Joined:
    Sep 4, 2015
    Messages:
    87
    Likes Received:
    14
    You might want to check the forums here for recommendations on Misumi bearings. I got some replacements but it's hard to tell if they were much better than the originals (I found a little ball in the box with the bearings, and didn't want to take risks). Certainly of you're in doubt, now is the easiest time to do something.
     
  5. jdix

    jdix Member

    Joined:
    Dec 20, 2015
    Messages:
    6
    Likes Received:
    1
    Thanks for the replies.
    Sounds like it maybe worth getting some more before I go any further with the build. I'll look into the Misumi ones as suggested.

    Cheers

    James
     
  6. Ualdayan

    Ualdayan Member

    Joined:
    Dec 21, 2015
    Messages:
    24
    Likes Received:
    8
    When I was doing the X axis assembly (on subassemblies, don't have frame together yet) you slide 2 bearings on, and then press the idler carriage and x-axis motor carriage on the ends of the rod - I noticed on mine, that one of the two bearings is loose enough that gravity can pull it down easily, but the other bearing almost wants to resist even hand moving it. Does gravity pull yours down?
     
  7. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    I think I have to help mine down. I have just tried a rod in the bed assembly. Should they slide by them selves?

    Another thing I noticed with especially one bearing is that it wants to rotate on the rod. When sliding it back and forward it always turns the same way. Kind of strange.
     
  8. Ephemeris

    Ephemeris Well-Known Member

    Joined:
    Nov 25, 2015
    Messages:
    296
    Likes Received:
    182
    Having bought from several vendors in the past, the cheap ones are definitely hit or miss. I've always thrown away the ones that want to spin since I assume they'll tear up the rods.
     
    Stian Indal Haugseth likes this.
  9. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Hmm.. This will delay my build as am about to start on the box. Soon it will be much more hassle to replace them.

    What do I look for in a good bearing?
     
  10. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    You won't be able to tell if it is good or not until you slide it on the rod.
    I rather choose bearings of known manufacturers. Or of a trusted source.
    Though the bearings the 3D print shops here in Europe sell are also cheap Chinese bearings of low quality.
    The only ones I know in Europe are the Misumi bearings. Other manufacturers like INA don't have that kind of bearings.
    @Henry feldman got his from ServoCtiy (?) and they seem to be good too.
    Don't know of any others...
     
    Stian Indal Haugseth likes this.
  11. Henry feldman

    Henry feldman Well-Known Member

    Joined:
    Sep 5, 2015
    Messages:
    969
    Likes Received:
    389
    ServoCity are the Actobotics guys, and are great for service and support. They aren't the cheapest around, but I have never gotten a bad part (now their website on the other hand can be a hot mess when trying to figure out which Actobotics part you want, but for servos, rods, motors and bearings it is very nice). I've bought some steppers (big) and powerful servos from those guys for robotic projects, and their service is great.
     
    Stian Indal Haugseth likes this.
  12. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
  13. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    You'd expect anything of those, sorry to say that.
    The Z axis is meant to move without force. In the situation you built the rods should fall down to the ground if you inserted them into the bearing as let the loose...
    On XY those could work, those are moved with force but the Z axis should go down by gravity and the lead screws just prevent it from doing so...
     
    Stian Indal Haugseth likes this.
  14. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Thanks @Alex9779 and @Henry feldman.

    Anyone knows a shop in Europe with short shipping with reasonable bearings? I might order a bunch.
     
  15. wahatever

    wahatever Member

    Joined:
    Sep 6, 2015
    Messages:
    14
    Likes Received:
    3
    I bought these ones http://www.misumi-europe.com/en/e-catalog/vona2/result/?Keyword=LMUW8 55 EUR + VAT including shipping. Only business to business so you need a VAT number.
    Have you measured the rods? I found that at least one of the rods where thicker than 8mm and none of the bearings will runs smooth on that rod. One was slighty thinner than 8mm (smoothRod.jpg) and the Misumi bearing run as smooth as what you should expect without slack. The Z rods are too thin in my humble opinion.
     

    Attached Files:

    #15 wahatever, Apr 20, 2016
    Last edited: Apr 23, 2016
  16. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Interesting @wahatever. If the rods are not at spec cheaper bearings could almost be better. Just test a bunch and match them as good as possible :eek:

    I have no business and VAT no. I'm currently checking with our norwegian 3d-printing facebook group if someone has an account.
     
  17. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    But this is intended.
    While sending out the very first kits there was a "Z issue" because the bed didn't run smoothly so they used a slightly different tolerance for the Z rods... You just don't wanna have play which was NOT the case for me at least... The Z Bearings run super smooth...
     
  18. wahatever

    wahatever Member

    Joined:
    Sep 6, 2015
    Messages:
    14
    Likes Received:
    3
    My z-bearings do not only run smooth, they are flying above the rod :). It looks like in Stian Indal Haugseth G+ movie. The bearing in SmoothRod.jpg is running smooth without play.
    Best is to order bearings and matching rods from the same supplier. I did not measure the rods until I was mounting the Misumis and noticed the differences between the rods.
     
  19. Old_Tafr

    Old_Tafr Well-Known Member

    Joined:
    Mar 7, 2016
    Messages:
    560
    Likes Received:
    75
    Fortunately I found all bearings worked fine (famous last words !! ) some were very slightly loose, some a little tight.

    What I did find helped a lot (obviously) was grease. I had some spray high performance lithium WD-40 which is great for getting the residue everywhere, like an anti-stick substance for the bed! Grease in a tin I found better and spread on a smooth rod and sliding the bearing up and down most seems to disappear inside the bearing with the surplus spread (to be cleaned up) at both ends of the rod.

    With this disappearing act there must be a lot inside the bearing doing some good. I'm not sure what is advised but packing bearings is usually good and this isn't an application where great speed, heat grease melting and running out etc. is a problem.

    So if a bearing is slightly rough, there is nothing to lose in packing it with grease and running a rod through and cleaning up the surplus, something to be done as a separate exercise before starting building.

    Spray was ok on the screwed rods, but still messy, grease from a tin spread liberally all down the rods and then the bed run up and down distributes it nicely. Plenty of grease here worked well in completely removing a little noise when moving the bed rapidly. Regular greasing here is good as there will be far more wear and so loss of accuracy if lubrication is neglected.

    But read this, totally contradicts several things I found work well, and I found that once assembled (otherwise you have to pack the bearing before you assemble the printer) the bearings I have do suck the grease off the rod and swallow it up.

    http://reprap.org/wiki/Linear_bearing
     
    #19 Old_Tafr, Apr 20, 2016
    Last edited: Apr 20, 2016
  20. Large

    Large Active Member

    Joined:
    Sep 12, 2015
    Messages:
    28
    Likes Received:
    7
    Anyone with experience from Fushi bearings?
     

Share This Page