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bearing replacement / advise needed
Hello,
I recently acquired a 96 VF1 with DC Servos. I have been working on here and there and finally had a chance to run parts on it. The surface finishing is not real good. The y axis does make noise... I believe it is the bearing item #11 in the picture, bearing, fafnir radial #304pp. (description is from the book) The noise is very prominent from this area and when touching there is vibration when moving back and forth. I have never change a bearing like this before. Is this pressed in and will I need a press to get it out? Also I was hoping someone would have a bearing number I can use to order a replacement. I would like to have it in hand when I remove the old one so I can install right away for minimal machine down time.
Again I am looking for advise and a bearing number. If anyone can help I would greatly appreciate it.
Thanks
Re: bearing replacement / advise needed
teamjnz
If that is the right bearing # 304PP then it would have a 52 OD 20 ID & 15 wide, (Bearing Grade Abec 5 or 7 if you can get it ) you want 2 RS, 2RS being rubber shielded, the ballscrew may be under tension by the nut on the back, you will have to know this nut torque number, it sounds like it will be more than that bearing, that is making the vibration, vibration is in most cases,comes from the Ballscrew/Ball Nut
SKF Bearing # 6304-2RS Abec5
Re: bearing replacement / advise needed
Thanks Mactec54. Have you replaced this bearing before? Was it easy to remove? Items #2 is the bearing housing and it bolts to the main casting. Would be best to remove the housing to take out the bearing or is this not advisable for alignment issues?
Re: bearing replacement / advise needed
teamjnz
No I have not done one on this machine, yes alignment could be an issue if you have to remove the Bearing Housing, but to just replace that Bearing I don't think you have much choice, if the Bearing housing is doweled or has a machined pocket were it fits, ( Usually on the sides of the bearing housing where it fits are machined, to suit a pocket) you won't have a problem with alignment if it has been machined like this
Re: bearing replacement / advise needed
The bearing you have highlighted is referred to as the support bearing and it is pretty easy to change out. It's been quite a while since I have changed one, but if memory serves correctly the bearing housing block has dowell pins for alignment. In my experience, however, this bearing does not go bad very often, but even if yours is not bad, it's not that expensive.
Most common issues that are bearing related are from #6 at the motor end called the thrust bearing. When bad, this can give bad finished and make a lot of noise; usually sounding something like wwhhrrrrrrrrrrrrr. ( how is that for sound effects! :D)
Usually not to bad of a job to replace, but since it is the Y axis, that makes it a bit more difficult due to access. If you do end up replacing the thrust bearing, do yourself a favor and take 15 minutes and pull back the left side X-axis cover to expose the motor end of the ball screw. Look under the gold motor coupling cover. Here you can see how the motor is bolted on, the motor coupling (#7) is connected, the lock nut (#10) and the mounting screws (#9) are situated. This will help guide you when doing the y-axis which is set up the same and a lot of times doing things by feel.
As a safety note, if your machine is equipped with a mechanical weighted counter balance, be sure to block it while working on the y-axis since your hands will be directly underneath the counterbalance weight. If it is a nitrogen system, E-Stop is sufficient.
Good luck!
Re: bearing replacement / advise needed / updated with video
Quote:
Originally Posted by
haastec
The bearing you have highlighted is referred to as the support bearing and it is pretty easy to change out. It's been quite a while since I have changed one, but if memory serves correctly the bearing housing block has dowell pins for alignment. In my experience, however, this bearing does not go bad very often, but even if yours is not bad, it's not that expensive.
Most common issues that are bearing related are from #6 at the motor end called the thrust bearing. When bad, this can give bad finished and make a lot of noise; usually sounding something like wwhhrrrrrrrrrrrrr. ( how is that for sound effects! :D)
Usually not to bad of a job to replace, but since it is the Y axis, that makes it a bit more difficult due to access. If you do end up replacing the thrust bearing, do yourself a favor and take 15 minutes and pull back the left side X-axis cover to expose the motor end of the ball screw. Look under the gold motor coupling cover. Here you can see how the motor is bolted on, the motor coupling (#7) is connected, the lock nut (#10) and the mounting screws (#9) are situated. This will help guide you when doing the y-axis which is set up the same and a lot of times doing things by feel.
As a safety note, if your machine is equipped with a mechanical weighted counter balance, be sure to block it while working on the y-axis since your hands will be directly underneath the counterbalance weight. If it is a nitrogen system, E-Stop is sufficient.
Good luck!
Thanks Haastec for your input, I appreciate your safety note. Looking at the X axis is a great idea since when I had the covers off I was thinking changing out the thrust bearings would be a real bear of a job. Looking at the X axis will be much easier the evaluate what needs to be done. I recorded this video before I saw your post. I did have the Y axis covers off to clean out chips several weeks back. Moving the Y ball screw by hand it was not smooth. I could feel the... hmm not sure how to describe it but like turning a stepper motor, it was stepping like it was a bad bearing. The finish is not real good when interpolating a radius or circle. Traversing the Y axis with the covers off it sounded like the noise was coming from the bear I point to in the video. If the thrust bearings are bad it would seem the noise is traveling through the screw. Definitely a wwhhrrring noise. :D
Do you know the size of the bearings? Mactec54 helped me out with the support bearing number and size. Are they the same bearing size?
Here is a video link
https://drive.google.com/open?id=0B-...RXc&authuser=0
Re: bearing replacement / advise needed / updated with video
Quote:
Originally Posted by
teamjnz
Thanks Haastec for your input, I appreciate your safety note. Looking at the X axis is a great idea since when I had the covers off I was thinking changing out the thrust bearings would be a real bear of a job. Looking at the X axis will be much easier the evaluate what needs to be done. I recorded this video before I saw your post. I did have the Y axis covers off to clean out chips several weeks back. Moving the Y ball screw by hand it was not smooth. I could feel the... hmm not sure how to describe it but like turning a stepper motor, it was stepping like it was a bad bearing. The finish is not real good when interpolating a radius or circle. Traversing the Y axis with the covers off it sounded like the noise was coming from the bear I point to in the video. If the thrust bearings are bad it would seem the noise is traveling through the screw. Definitely a wwhhrrring noise. :D
Do you know the size of the bearings? Mactec54 helped me out with the support bearing number and size. Are they the same bearing size?
Here is a video link
https://drive.google.com/open?id=0B-...RXc&authuser=0
I can't view your video at work, but I would bet money that the problem is with the thrust bearing and not the support bearing.
The thrust bearing is an assembly of 2 bearings(I believe) in it's own housing; I have never disassembled one. I would suspect that there are buid specs to maintain if rebuilding one but I have no idea what that would be or if Haas would even provide them.
I am all for DIY repairs but this is one part that I would advise you bite the bullet and buy from Haas. It's a few hundred bucks, but it can potentially be cheaper in the long run vs rebuilding blindly on your own when factoring in time and potential errors. You don't want to do the y-axis thrust bearing twice. Call your dealer for current pricing and p/n verification.
Also, your best access will be to remove the lube panel completely and work from the rear of the machine. I am about to do one for the y-axis myself in the next few days.
Good luck!
Re: bearing replacement / advise needed
Quote:
Originally Posted by
teamjnz
Oh this is good news. I didn't realize the thrust bearing was sold as a package. I thought a dyi rebuild was the option. I would rather buy it instead of rebuilding to reduce down time. Does the servo motor need to come out too? I could be place the carbon brushes at that time too. I have not taken off the X axis way cover to review what I will be getting into.
Thanks for your help.
Yes, the servo motor will come off first after loosening the ball screw side of the motor coupling. This way the coupling comes out with the motor. Then you can remove the lock nut and then unbolt the thrust bearing. One of the challenges for the y-axis is the lack of visibility while reaching in to loosen the motor coupling. For me I have to do it all by feel; this is why I suggest looking at the x-axis first. The biggest challence is reinstalling the motor with coupling back onto the ball screw while blindly lining up the key in the ball screw and coupling. Getting excited yet?!?!?! :wee:
Some helpfull tools will be some hex head sockets for a ratchet (standard), long extensions, a good light and a telescoping inspection mirror.
Good luck and let me know how it goes.
Re: bearing replacement / advise needed
Since the original post I have replace several thrust bearing on a couple older machines I have. I choose to replace the bearing in the bearing pack instead of purchasing the entire bearing pack, saved some bucks.. It is pretty simple if you are mechanically inclined. One thing if someone chooses to replace the bearing instead of the entire pack opening up the pack can be a challenge if you don't have a way to hold it and unscrewing the preload cap. I happened to have another machine so I was able to bore a round pocket in some soft jaws to clamp the bearing pack. Once unscrewed pay attention to how the bearing come out since they are directional. Install new bearings, tighten preload cap to approximately the same as when you took it off, done. Install it back in the machine. It will take several hours but the reward of a quite smooth axis is good!
