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  • Lathe Spindle Bearings

    Hi everyone! New here, first post.

    I have a Harbor Freight mill/ lathe combo machine that I got back in high school. It's been sitting in my parent's barn (not climate controlled) for the last 10 years. I finally have some space for it, so I'm working on cleaning it up, getting it in as tip-top shape as I can.

    One of the lathe spindle bearings is bad (on the drive side of the spindle). I'm looking to replace it, hopefully with something better than was in there originally; but I don't know where to start, and have some questions:

    1. It originally was a ball bearing, 35 mm ID, 72 mm OD. Am I better off replacing it with a roller bearing? What are the pros and cons?
    2. What do I look for in finding a decent quality bearing that isn't going to kill me with the price? Are Granger or McMaster Carr good places to look, or should I call a bearing specialty company?
    3. The manual doesn't say anything about the type of bearing grease to use on the existing bearings (the other bearing is a tapered roller bearing). Does it matter? What do I look for in a bearing grease?

    Any pointers would be much appreciated.
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  • #2
    Hi, and welcome to the forum!

    Truthfully, I'd replace it with the factory equivalent. With that machine you probably won't see any difference with a higher grade bearing, and it won't be worth the cost or hassle of finding a precision bearing.
    Southwest Utah

    Comment


    • #3
      +1 on what Chipmaker4130 said.

      Replace with factory equivalent. The back bearing may not influence radial runout much. But may influence axial runout if it's used as a thrust bearing. Increasing accuracy of the back bearing will have little affect on accuracy of the assembly.

      In any case, the tapered roller in the front would be most important for radial accuracy. Take care when reassembling and setting preload on the tapered rollers. They can be damaged easily if preloaded too much.

      Hope this helps.

      Best Regards,
      Bob
      Last edited by rjs44032; 03-10-2021, 07:27 PM.

      Comment


      • #4
        Welcome to the forum, Luke, as already said, you might as well get the exact same type of bearings as the old ones. That said, you can get one of the big brands which will be higher quality than the originals. Careful fitting of the new bearings will pay dividends and if grease is used, then lithium base high melting point will do, and be sure to leave at least 60% of the filling air and only 40% grease. The preload should be very slight, a rule of thumb is that the headstock should get warm, not hot after running at speed for 20 minutes.There should be no measurable axial play in the spindle.

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        • #5
          Here's a vid of This Old Tony doing the bearing change.
          https://www.youtube.com/watch?v=HYOgmhpBUJs

          Comment


          • #6
            Thanks for the tips! Any thoughts on where to source the replacement? I could order a ball bearing with the same dimensions from McMaster for $15... Or am I better off calling around?

            When it comes to re-assembly -- can you point me in the direction of any instructions for "setting preload"? I've seen that term a number of times, and I have a bit of an idea of what it means... but I'm not sure how to go about it. This assembly was difficult to get apart, and I'm not at all sure how I could do any fine adjustments, considering how hard I had to hit it to get the shaft to move out of the ball bearing at all.

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            • #7
              I make chips that video was pretty informative, thanks!

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              • #8
                Hi Luke, other sources for bearings depends on where you live. Kaman Industrial or Motion Industries are 2 good sources and will usually be able to give you a choice between a cheap bearing and one of better quality, usually without a great increase in price..

                Comment


                • #9
                  Originally posted by Luke_M View Post
                  Hi everyone! New here, first post..............
                  1. It originally was a ball bearing, 35 mm ID, 72 mm OD. Am I better off replacing it with a roller bearing? What are the pros and cons?
                  2. What do I look for in finding a decent quality bearing that isn't going to kill me with the price? Are Granger or McMaster Carr good places to look, or should I call a bearing specialty company?
                  3. The manual doesn't say anything about the type of bearing grease to use on the existing bearings (the other bearing is a tapered roller bearing). Does it matter? What do I look for in a bearing grease? Any pointers would be much appreciated.
                  1. No, Stay with the Ball Bearing -Going to another taper roller presents new problems , that you don't want to handle now
                  [ besides sizes (metric versus inch) and adjustment issues, Spindle may need to be changed ]

                  2. Ball bearings come in grades starting at 9 (the best $$$$ ) going down to 3 . ( Although "0" is better than 3 for some reason) I doubt your machine had any better than a Grade 3
                  Ball Bearings come is several types , Light duty, Medium and Heavy, as well as Deep Groove and Angular Contact
                  I do not know your machine at all, but your bearing size says it is a Light series 207 (or 6207)...if the width is 17 mm ?
                  If it is a Angluar Contact bearing for that size, it would be a " 7000 series number like 7207 . (SKF- FAG) or a 135Ac (Norma FAG)
                  Note, if it is a Angular contact, "Direction" of the installation is very important ! Thinner OD Ring must be facing the outside of the spindle .
                  I presume it is an ordinary 207 and was not critical in specs. As others have pointed out, using a good bearing made by SKF or FAG or Norma FAG is
                  almost a necessity ! I do not trust Chinese bearings and have encountered several issues with there bearings previously. I am sure they do make good bearings , but
                  they seem to send garbage to the USA . The best bearing maker for precision in the world is Barden ... and to give you an idea, I bought a matched pair of Barden 207" back in the year 2000 and
                  paid $ 311 for them .. You can use standard class bearing as they primarily handle drive loads and I think will cost about $ 40

                  3. I like Oil for spindles , but if you use grease its Ok. the previous recommendation for a Lithium base grease is good . I prefer grease from "Lubrication Engineers", it a red grease and is superb

                  Stick with SKF or FAG ! and Welcome aboard !
                  Rich

                  Edit: My comments on grade or scale refer to ABEC ratings, not metric grades which use "P" and may be opposite in number
                  Last edited by Rich Carlstedt; 03-11-2021, 11:09 AM.
                  Green Bay, WI

                  Comment


                  • #10
                    If you fit taper rollers both ends, the axial movement will get less as you tighten the nut until it just dissapears. This is the point at which the rollers are touching the races fully. The spindle should be free to turn by hand. You should invest in a lever type indicator and magnetic stand to be sure the preload is just about to start. An alternative bearing is the angular contact type with rubber seals. They are better than the original ones and stay lubricated for life. They must be fitted the correct way round, but the preload is still used.
                    I have bought bearings online from a specialist bearing stockist. when you put the bearing sizes into their site, there will be a number of price options, from cheap to expensive, and the mid to high end are much better than the cheapies.
                    Take care fitting the bearings, they can be damaged by hammering or pressing on the wrong part.
                    Last edited by old mart; 03-10-2021, 03:59 PM.

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                    • #11
                      Rich Carlstedt That's right, the bearing is marked "TCC" and "6207E" It looks like that means it was originally "Light Duty"? So in this case, there's no advantage to changing the type; only in buying better quality, correct? I mean, since I have it apart, I may as well get the best part I can -- to the point that it actually makes any difference, that is.

                      jmm03 I'm in SE Michigan; it looks like Motion Industries has nearby locations. I'll have to give them a call tomorrow.

                      old mart Is that delicate tightening process part of what Rich is referring to as "new problems I don't want to handle right now"?

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                      • #12
                        Luke- you got away easy- nobody trashed-talked your combo machine. Not yet anyway. I'm not going to either. But I will suggest that it didn't come with the best of bearings, and you won't be hurting anything by not putting $500 replacement bearings in it. I don't think it's worth bothering to upgrade them- but it would be worth buying say a Japanese bearing or American made one, and not a Chinese one.
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                        Comment


                        • #13
                          darryl Fair enough -- it's a cheap machine, as they go, and it probably doesn't make sense to pour a bunch of money into it, when it can only be improved a certain amount. That does make me wonder though -- and this is a bit OT -- what are the limiting factors on precision with a machine like this? Is it the quality of the ways? The tolerances of the feed screws? Other factors?

                          I've seen some discussion from people with the same machine who claimed a lot of improvement with certain upgrades (i.e, replacing the bearings, switching from belt drive to gear drive, extending the feed screw to add auto feed, etc...) If you were trying to improve the precision, what do you think would give the most bang for the buck?

                          Comment


                          • #14
                            Originally posted by Luke_M View Post
                            darryl ....... That does make me wonder though -- and this is a bit OT -- what are the limiting factors on precision with a machine like this? Is it the quality of the ways? The tolerances of the feed screws? Other factors?

                            .......
                            I would say all of the above, and many more besides are why it is not a high precision machine..

                            It's fine for what it is, and if you did not buy it as it presently is, you are out nothing if you spend up to what you could buy one like it for. Think of it that way.

                            You want a lathe, the lathe will cost you $XXX. You find one that is not working, but you can spend "more than it is worth", but still less than $XXX, and make it be a working lathe.

                            Not a thing wrong with that, you got a lathe for less than you otherwise would have to spend.
                            CNC machines only go through the motions

                            Comment


                            • #15
                              Others here have more experience than me but for a light duty simple machine such as you have I'd go with standard grade rollers on both ends. Get them from whoever. Your local bearing house, ebay and so on. Cheap and easy to implement. Grease em up and tighten the spindle until you have slight drag and run it. If it builds heat you can feel in the bearings after a half hour, back off on the adjustment a touch.

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