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Thread: Replacing Bearings and Pulleys -Table Saw Rebuild Query

  1. #1
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    Replacing Bearings and Pulleys -Table Saw Rebuild Query

    Hello,

    I am in the process of refurbishing my 10" General Model 350 table saw that I have owned for 20+ years. The bearings are NSK 6203DU's. I bought (according to the parts list I have) 6203-2RS bearings some time ago for this purpose. Should I order the "DU" type bearings or is it acceptable/suitable to use the -2RS bearings I bought already? I know nothing about bearings... :O(

    Also, both the motor and arbor pulleys appear to be in good condition (to my very uninformed eyes). Given that I have the saw apart, should I go ahead and replace them both anyway?

    Last question - the motor is a 5 HP 220 volt Baldor, which has a grease nipple in the housing at the shaft end. Should I be (and have been) lubricating this?

    Thank you for any help you wish to offer.

    Regards,

    Joe H.

  2. #2
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    You may be able to google the difference in the bearings. My advise would be to call a bearing and drives dealer and ask them. These folks know their stuff and will give you the advise you need. As for the grease zert on the motor, a squirt occasionally is all that is required. Too much grease is just a bad as no grease. Too much will allow the seals to blow out and then saw dust and other contaminants can get in ruining a bearing in a hurry. Of course it depends on how much yu use the saw. As a hobbyist, I'd say once every 6 months would do. If hard use, maybe once a month.
    SWE

  3. #3
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    If you replace the arbor bearings, you should also replace the motor bearings as they generally go bad first. They are likely open on one side at least but you can just buy shielded and remove one. An RS bearing is shielded and if used, the machine will be designed ( usually ) to keep any grease that expels close enough to the bearing for minimal loss. Shielded will have a higher rpm limit than sealed and allow for tighter clearance which is good in a spindle application. I suspect the bearings are small enough that sealed are fine. When replacing them, stay with standard clearance. SKF Explorer is a good choice. Any SKF that lists JEM is a C3 clearance- great for motor bearings, less so for spindles. Most bearings brands will have an ABEC 3 slightly better bearing like the Explorer so just ask. Dave

  4. #4
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    I have rebuilt at least five cabinet saws. Just replace the arbor bearings with shielded bearings (it sounds like you already have them) and the motor bearings with sealed bearings and call it good. Also remove the grease zerk fittings and replace them with a plug. The pulleys should be fine. I have never had to replace table saw pulleys.

  5. #5
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    The bearings you have will be fine. If the sheaves are worn you'll see a noticeable step worn on the side of the groove. That's when they should be replaced.

    Believe it or not a motor that size running under a fairly light load needs a couple shots of grease about once a year maybe less depending on how often it's run.
    Confidence: The feeling you experience before you fully understand the situation

  6. #6
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    Quote Originally Posted by Joe Hollis View Post
    Hello,

    I am in the process of refurbishing my 10" General Model 350 table saw that I have owned for 20+ years. The bearings are NSK 6203DU's. I bought (according to the parts list I have) 6203-2RS bearings some time ago for this purpose. Should I order the "DU" type bearings or is it acceptable/suitable to use the -2RS bearings I bought already? I know nothing about bearings... :O(

    Also, both the motor and arbor pulleys appear to be in good condition (to my very uninformed eyes). Given that I have the saw apart, should I go ahead and replace them both anyway?

    Last question - the motor is a 5 HP 220 volt Baldor, which has a grease nipple in the housing at the shaft end. Should I be (and have been) lubricating this?

    Thank you for any help you wish to offer.

    Regards,

    Joe H.

    Different manufacturers use different suffixes to call out shielded and sealed versions. I would use a double shielded bearing and NSK is a good brand so is Nachi. You can get either from a local industrial distributor in your area. Kaman, Motion or Applied Industrial are large national chains. For the pulleys, is there wear from the belt inside on the pulley face? if yes I would replace them if not you should be fine. Thanks. Brian

  7. #7
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    I misspoke earlier. RS are sealed in most bearings ( NSK uses DDU ) not shielded. ZZ are double shields. Natchi Quest are equivalent to SKF Explorer in precision. Dave

  8. #8
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    Thanks to all of you that have replied. I will do as suggested and replace both my arbor and motor bearings. Replacing the arbor bearings appears to be straightforward; I've never had an electric motor apart before, but Professor YouTube tells me that if I rent a bearing puller, I should be able to replace the bearings in the motor myself as well.

    Dave Cav said I should replace the existing grease fitting with a plug... Do I just remove the existing grease fitting, pump "some" electric motor bearing grease into the hole and then plug the hole with a different fitting afterwards? Sorry, but I've never lubricated the motor before (likely I should have..) and don't want to damage up. This is a spec motor that would cost $$$ to replace. It seems I cannot attach images to this post...


    Best regards,

    Joe H.

  9. #9
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    Joe he is telling you to put a plug in the hole and NOT to grease it. Bearings are preloaded with grease and should easily last 10-20 years.

  10. #10
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    You might buy a bearing splitter on the bay. They make the job much easier. Forces are low so buy a cheap china made gear puller to remove the bearings.
    BIL LD

  11. #11
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    If it was me I wouldn't do the motor bearings (unless I felt they were bad) just because I was doing the arbor bearings. The motor is easy to remove and as long as you take a good measurement on where the pulley is so you can put it back in the same spot doing it down the road isn't a big deal. The NSK bearings on your arbor are good quality bearings but even still are most likely not the same brand as the ones on the motor. So life expectancy may not be the same. If you are the type of guy who wants to just get everything done and know you have it set for the next 20 years then by all means replace them. It's been my experience with Baldor is they spec exactly what they want (bearing size, clearance, and grease) and they don't cheap out.

  12. #12
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    Quote Originally Posted by Mike Kees View Post
    Joe he is telling you to put a plug in the hole and NOT to grease it. Bearings are preloaded with grease and should easily last 10-20 years.
    Yes, this. Sorry I wasn't clear before. Every motor with zerk fittings I have disassembled for repairs has had the end bells and usually the windings packed with grease, dirt and sawdust. Good American, European or Japanese bearings should be lubricated for "life" which usually works out to about 20 years. Cheap Chinese bearings, maybe not, and I don't necessarily trust the grease they use, either.

  13. #13
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    Radial bearings should have a 25-30% fill with a Polyrex grease or equal. You don't want to overfill them. Gentlemen explained to me it was like walking through a pool with water up to your knees or up to you neck. More grease only creates more drag and more heat; which shortens bearing life. The lower ball path picks up the grease and distributes it as the balls move around the inner race of the bearing.

    Brian

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