Okuma lathe lb-3000 spindle repair - Page 2
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  1. #21
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    Quote Originally Posted by Other Brother View Post
    .....One thing you can do to help prevent coolant contamination is add cleaning the drain at the bottom of all of your lathe spindles to your PM schedule. It takes 30 minutes and well worth the time to make sure the coolant drains from the labyrinth area.
    This ^ should be on everyone's PM schedule.

    A substantial number of the lathe and HMC spindles I have had to replace, had plugged up drain holes in the labyrinth seal that allowed coolant to get into the front bearing.

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    Quote Originally Posted by bigshooter2 View Post
    Hi OB

    This labyrinth that you mention, is this part of the bearing itself or is it a separate part? Looking at the OKUMA parts book, main spindle unit drawing there is a separate part called "labyrinth".
    I didn't answer this question, sorry. The labyrinth in the parts book is actually a slinger ring and I have never replaced this part. The labyrinth is actually a 3 part system and the parts book calls 2 of them collars. The inner labyrinth will get replaced as this collar sets the preload on the front tapered roller bearing and gets ground to a dimension established by gage blocks +.0000/-.0002". The outer labyrinth/collar is what the outer race of the front tapered roller bearing contacts. I always check the housing with depth mics but have never had to grind to fit the outer collar. These 2 collars are what I call the labyrinth seal and both go on the spindle before the bearings go on. There is a series of grooves in each to keep coolant out of the spindle bearings.

    The inner collar/labyrinth gets locked in place by the tapered roller bearing, inner spacer, a set of thrust bearings, and a lock nut. The outer collar/labyrinth floats until the spindle is mounted in the head and gets locked in place when the front spindle housing is bolted to the head casting. There is a drain hole in the outer collar that needs to be at the bottom when locked in place.

    The labyrinth in the parts book is a slinger ring and is the last part that goes on after the spindle has been installed in the head and bolts to the spindle arbor. It rotates and slings the coolant to the drain. The inner collar/labyrinth and slinger ring spin with the spindle shaft and the outer collar/labyrinth is stationary with a drain hole at the bottom.

    To help minimize coolant contamination when using live tools, make sure the spray is not directed at the clearance gap between the front housing and the outer diameter of the slinger ring, and keep the drain clean.

    To clean the drain you need to remove the chuck, slinger ring and the drain block/small sheet metal covers on the bottom of the housing. Remove the chips and coolant residue and use a wire in the holes to clear the drain, never use air.

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    A lot of CNC turning centers now have a sheet metal “dog house” that bolts to the firewall and wraps around the body of the chuck, to help prevent coolant ingress when live milling.

    I would definitely recommend retrofitting one, if the machine doesn’t have it.

    ToolCat

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    Quote Originally Posted by Other Brother View Post
    No, nothing was done other than replace the failed bearings. What I would recommend is where you are aiming the high pressure coolant when milling on a lathe. The problem as far as I know was the bearing design. One thing you can do to help prevent coolant contamination is add cleaning the drain at the bottom of all of your lathe spindles to your PM schedule. It takes 30 minutes and well worth the time to make sure the coolant drains from the labyrinth area.
    Will do OB. Thanks.

    Update: the machine headstock is at the spindle repair facility in the US and they informed me that they will be tearing it down in soon. I will post again when I know more.

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    The first two photos are of cages from two different LB3000 spindles that I rebuilt in one week. This is what happened on all of the ones I rebuilt, the front roller bearing cage always looked like this. The third photo shows the bearings removed from one of those spindles, and the last photo is of the spindle just after removing it from the machine before starting tear down.
    Attached Thumbnails Attached Thumbnails 20160106_075341.jpg   20160122_103838.jpg   20160328_094749-1.jpg   20140613_115321.jpg  

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    Quote Originally Posted by Other Brother View Post
    The first two photos are of cages from two different LB3000 spindles that I rebuilt in one week. This is what happened on all of the ones I rebuilt, the front roller bearing cage always looked like this. The third photo shows the bearings removed from one of those spindles, and the last photo is of the spindle just after removing it from the machine before starting tear down.
    WOW!! I can't believe how degraded the cages are. How many hours would you guess they had on them at that point?

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    Quote Originally Posted by litlerob1 View Post
    WOW!! I can't believe how degraded the cages are. How many hours would you guess they had on them at that point?
    The first had very little time, probably 1000 hours of actual spindle running time. The 2nd one around 2500, so neither one should have failed. Some of the ones I tore down had missing rollers like the photo of the bearing, but the spindles would spin freely. It's like the roller would get ground up as the spindle ran but every now and then it would lock right up and start screeching. It's odd how the rollers would just disappeared like that.

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    Are there actually rollers missing or are they just all bunched up because the cage is gone?

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    You know what, I believe you are correct. That was probably the case on the others where I thought a roller was missing. Forrest/trees! lmao

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    Bigshooter,

    Have you gotten any updates on from the spindle repair facility? Curious to know your serial # and manufacture date, I have an LB3000 that just lost spindle bearings on 5/31/19!

    I hate we're both experiencing this situation. I have a service tech scheduled to be here sometime withing the next few days.

    OB, thanks for providing the pictures of the fixture and the damaged bearings. I have a feeling through different conversations with different people the machines with faulty bearing cages were manufactured sometime between 2013/2014..

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    Hi pdhamm

    Believe it or not I just got the spindle back on Monday. This took a ridiculously long time. I was able to view the "OKUMA BULLETIN" that was provided to the machine tool sellers. I was not able to make a copy, only make some notes; it stated that machines made after Feb 2013 had a bad bearing with bearing cage failure in bearing# NN3028HSKUP-20V11. I do not recall an end date but I am sure they remedied the situation at some point. My machine manufacture date is Feb 2013 so according to this bulletin AND my machine tool distributor, my machine/serial# was not affected and does not have the bad bearing BUT when the bearings were pulled from the spindle the front tapered roller bearing cage was in pieces and guess what bearing# was etched on the bearing race? Yep you guessed it...bearing # NN3028HSKUP-20V11. I will provide more details of my experience in another post - coming soon. Sorry for the late reply.


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