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Okuma lathe lb-3000 spindle repair

bigshooter2

Plastic
Joined
May 13, 2019
Has anyone out there done a spindle repair on this machine? The spindle on my machine is ceased and its most likely bearings. I need to pull the spindle from the PREX motor in order to have a look at the bearings but I am not sure exactly how to do this. Any advice would be greatly appreciated. Please Help! Thanks.
 
I have rebuilt close to a dozen of the prex spindles on the LB 3000 ex and 4000 ex. It's not a simple job and without renting the cradle support from Okuma it is a very difficult job, not impossible, but the cradle support is a time saver. The kit they rent supports the permanent magnet and also aligns the pickup/speed sensor which can not be aligned once the spindle is in. I can give you some tips if you are set on doing it yourself, but I wouldn't recommend that. The front tapered roller bearing was bad on every prex spindle I rebuilt.
 
Some photos of a prex spindle. You do not need to removed the big plate on the back of the housing. Also note the threads in the cropped photo. Left hand and right hand that locate the brake rotor adapter. That will screw with your mind. Measure the distance of the brake rotor before removing, that's what those threads set, the distance of the brake rotor. I wish I had one of the magnet, but keep your pockets empty when handling the magnet. :)

Every detail is marked with a number to orient each in relation to the chuck locating pin and balance.
 

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Useful pics. OB, do you have an estimate for the weight of the bare spindle itself? Just curious, it looks pretty beefy.

I don't have a clue of weight, but it's all 2 of us could do to lift and thunk it down on some wood to get the magnet off. It's the heaviest of all the spindles I ever rebuilt. A few more photos of the puller and how it is supported when pulling.
 

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There's a song- "know when to hold em, know when to fold em". Good luck!

Know when to walk away! Know when to...Ya I fold. I hired a local machine tool service company to remove the entire head stock. I am going to crate and ship this unit to a spindle repair shop in the US. There they can do the bearing work, preload, run in, etc. You never count your money, when your sitting at the... that song will be in my head all day now.
 
I have rebuilt close to a dozen of the prex spindles on the LB 3000 ex and 4000 ex. It's not a simple job and without renting the cradle support from Okuma it is a very difficult job, not impossible, but the cradle support is a time saver. The kit they rent supports the permanent magnet and also aligns the pickup/speed sensor which can not be aligned once the spindle is in. I can give you some tips if you are set on doing it yourself, but I wouldn't recommend that. The front tapered roller bearing was bad on every prex spindle I rebuilt.

Hi OB

You mention that the front tapered roller bearing was bad on every PREX spindle that you have rebuilt. Could you please elaborate. Would you say a design problem, pre- mature bearing failure? The reason I ask is that there is only 3000 spindle hours on this machine. No longer under warranty. Needless to say I am pretty disappointed. Although is it possible that it is not bearings?

Thanks for the pictures and the information. The spindle repair shop that will be doing the work says they have repaired this type of spindle/motor/machine before and the local machine tool service company that is removing the head stock deals with them regulatory. Now I can pass this info on to them just in case. The more info the better. Thanks.
 
Yes on the bad design. Yes, it's most likely the front tapered roller. I was wondering if anyone would question why so many. I should have stated this yesterday, but Okuma had a list of serial numbers that had the bad bearing design. The cage would fail on the roller bearing right around a year, depending on how many hours on the machine. You still may be able to get some support from them. Did you buy it new?
 
Hi OB. Yes i bought the machine new. It is several years old but only has 3000 spindle hours on it. Where can i find more information on this and these serial numbers. Please please please let it be one of those machines. This has already been hard my machining business and i havent even paid the repair bill yet. The machine tool distributor did not mention anything about this even when i asked if i could put a claim in to OKUMA for suspected pre-mature bearing failure. Sometimes i feel like they are working against me instead of with me.
 
I looked for the serial number list and don't have it. I never hid anything from a customer but when I told them how many I had done they knew there was a problem. I got my tit in a ringer many times with my company because I was always up front with the customer. Maybe that is why I have a good customer base today.

Your distributor has the list, trust me. I probably have a few photos of what that front bearing will look like when it is pulled. There will be missing rollers and the gage will be in pieces.

I think a big part of the problem was the labyrinth when using live tools and blasting the stationary main spindle with high pressure coolant. The labyrinth is designed to work when rotating, not so good when stationary, if that makes sense.

The squeaky wheel gets the grease, and Okuma warrantied a lot of these that were well past the one year warranty, at least that is what is heard. ;)
 
I looked for the serial number list and don't have it. I never hid anything from a customer but when I told them how many I had done they knew there was a problem. I got my tit in a ringer many times with my company because I was always up front with the customer. Maybe that is why I have a good customer base today.

Your distributor has the list, trust me. I probably have a few photos of what that front bearing will look like when it is pulled. There will be missing rollers and the gage will be in pieces.

I think a big part of the problem was the labyrinth when using live tools and blasting the stationary main spindle with high pressure coolant. The labyrinth is designed to work when rotating, not so good when stationary, if that makes sense.

The squeaky wheel gets the grease, and Okuma warrantied a lot of these that were well past the one year warranty, at least that is what is heard. ;)

You are a good person and thank you for being so honest. Customers have a right to know these things.Everyone has non-conforming product once in a while and that is why quality systems and the concept of continuous improvement exists. The right thing to do is to address the issue up front so that the customers do not suffer. These are world class machines and should be backed by world class service. It sounds like you did your customers a great service by being honest. I have a call in to OKUMA CORPORATION US inquiring about my machine and bearing failure. I was told that someone will call me back and I expect it will just be the local machine tool distributor service manager but hey, its a start to getting some answers. I will post when I know more.
 
Useful pics. OB, do you have an estimate for the weight of the bare spindle itself? Just curious, it looks pretty beefy.

just some weight info: I had the headstock with M140 spindle removed from the machine today and weighed it for shipping purposes. The unit weights 1640 pounds.
 
Yes on the bad design. Yes, it's most likely the front tapered roller. I was wondering if anyone would question why so many. I should have stated this yesterday, but Okuma had a list of serial numbers that had the bad bearing design. The cage would fail on the roller bearing right around a year, depending on how many hours on the machine. You still may be able to get some support from them. Did you buy it new?

Man would I love to get a copy of that list. or even just post the machine serial# and someone can tell me if my machine is on that list. Does anyone out there have and is willing to share this information? I bet other OKUMA owners would like this info too.
 
I looked for the serial number list and don't have it. I never hid anything from a customer but when I told them how many I had done they knew there was a problem. I got my tit in a ringer many times with my company because I was always up front with the customer. Maybe that is why I have a good customer base today.

Your distributor has the list, trust me. I probably have a few photos of what that front bearing will look like when it is pulled. There will be missing rollers and the gage will be in pieces.

I think a big part of the problem was the labyrinth when using live tools and blasting the stationary main spindle with high pressure coolant. The labyrinth is designed to work when rotating, not so good when stationary, if that makes sense.

The squeaky wheel gets the grease, and Okuma warrantied a lot of these that were well past the one year warranty, at least that is what is heard. ;)

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". My concern is if this spindle is rebuilt using the same bearings and same spindle unit parts is this failure just going to happen again after another 3000 spindle hours?? When you rebuilt the PREX spindles what did you do to prevent the bearings from failing pre-maturely again?

Also, this spindle unit was making a bit of noise (normally the spindle is super quiet)and my machinist mentioned that after doing live tooling work (C axis/Y axis milling) the spindle noise would be louder as the spindle started to rotate and then it would quite down over time so yes this makes sense to me.
 
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.
 








 
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