Announcement

Collapse
No announcement yet.

Lathe build underway: Part 1, the spindle

Collapse
This topic is closed.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #61
    Robert, yes yes , I agree now that I know you are talking about run out using a test bar!!
    But that's also a measurement of how well the internal taper is ground and has nothing at all to do with the bearings.
    Measure the outside of a mini lathe spindle and you'll get around .0003" runout.


    If using a center one would usually return the tip true and now that horrendous internal taper runout is gone and all that is left is what's in the bearings.

    Steve

    Comment


    • #62
      "If the ball bearings are perfectly spherical and the races are perfectly smooth, then there's only the rolling action which means that it should in theory never wear."

      Because of the varying surface speed of the balls at different distances from the center, there will be scrubbing between the balls and the races.

      I can't think of anything except a needle bearing that is purely rolling.


      The shape of the grooves in ball bearing races is intentionally not exactly the same as the ball. Under very light load the ball will have a point contact on each race with a pure rolling action. As the load is increased both the ball and the races deform at the point of contact with the result that the point of contact becomes a contact patch.

      The difference in actual position at the edges of this patch and the theoretical position is extremely small even with a significant load. How much deformation takes place is also dependent on if and how fast the bearing is turning. At a standstill the deformation is at maximum which is why the maximum load spec for a static load on a non rotating ball bearing is much lower than the running spec.

      As the load is increased while the bearing is turning the deformation of the components generates heat. The balls heat up more than the races as they have much less mass and can only dissipate heat via contact with the race. As they heat up the properties of the metal change. Above about 150 to 200 degrees F those properties change enough to weaken the balls. How fast this happens depends on the load and rpm. Part of the load is caused by the centrifugal acceleration of the bearings against the outer race.

      If the balls become hot enough they lose strength and this will happen before the races. When that occurs the material in the contact patch will begin to be deformed enough to exceed the plastic yield limit. When that happens the surface layer of tbe ball will begin to form microcracks all over the surface of the ball. The next stage is that pieces of the surface will begin to break away, a process called spalling. When this occurs those pieces then become foreign objects in the races and the further destruction of the bearing under load is both assured and almost immediate.

      Robert, the spec on the Deckel is listed as "(maximum) permissible". I would not expect to see it at or even near that spec limit.
      Last edited by Evan; 01-02-2009, 07:03 PM.
      Free software for calculating bolt circles and similar: Click Here

      Comment


      • #63
        Originally posted by John Stevenson
        OK it will work, all I was pointing out for anyone who fancied copying what Even is doing is that there are better ways and just as cheap as single angular contact bearings are used on many things, Mini front wheel hubs for one and I'll bet they are only $5.00 a bearing from the discount car part places.

        Lets face it most Chinese import machines often have just a deep groove ball race back and front and they work.

        Evan is trying to read more into his choice of bearing than is actually there, OK so it's a double row angular contact bearing, made out of billet but it's not the BEST double angular contact bearing out there and the reason has been explained. Evan managed to gloss over his incorrect link quite conveniently.

        Spin Doctor summed it up and if he hasn't the credentials then no one has.

        Anyone want to take bets on what the published run out will be ?

        .

        John is probably right . But it is what Evan has and he said he was going to use what he had and this is it . I have done the same thing and it worked . Built a surface grinder once with a pair of hand fitted Barten bearings and it worked just fine.

        Would some one tell me why this group get so carried away over bearings . We have all been here more than once.
        Last edited by lane; 01-02-2009, 07:17 PM.
        Every Mans Work Is A Portrait of Him Self
        http://sites.google.com/site/machinistsite/TWO-BUDDIES
        http://s178.photobucket.com/user/lan...?sort=3&page=1

        Comment


        • #64
          Originally posted by S_J_H
          Measure the outside of a mini lathe spindle and you'll get around .0003" runout.
          If you squint really hard, you can read that the first test on the Sieg chart is testing the runout of the spindle nose. That has a max runout of .04 mm, or 16 thou.

          Or put it a different way: there's no way that a Mini-lathe is going to come anywhere close to a Deckel's runout
          "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

          Comment


          • #65
            Originally posted by Evan
            Normally you would be right Lane but I have a Tesa dial indicator that is graduated at one micron per division. That's 0.0000397 inches per division.



            I centered up the bearing journal to the best of my ability in the 4 jaw. I was able to get it to about plus/minus 3 microns deviation per rotation. That's +/- 0.00012", a touch over one tenth runout each side at the journal. It took me half an hour before I was convinced I couldn't make it closer than that. I will have to investigate why.



            Then, measuring to the outer race and holding the outer race still while rotating the spindle I measured about +/- 4 microns per rev.
            I rotated the bearing to various positions and always obtained the same result. I also saw the same result with the lathe running slowly in back gear.



            So, it appears that the bearing has a couple of microns runout. Thanks for your offer Robert but I don't think I will need that bearing.

            2 microns = 0.00008 inches.

            Some of that is your south bend I think also. After you get the real housing built for the spindle you are making and the spindle all buttoned up check again it Will be closer I bet.
            Every Mans Work Is A Portrait of Him Self
            http://sites.google.com/site/machinistsite/TWO-BUDDIES
            http://s178.photobucket.com/user/lan...?sort=3&page=1

            Comment


            • #66
              Would some one tell me why this group get so carried away over bearings . We have all been here more than once.
              Good question. I had the same sort of static over my choice to use PTFE linear bearings on my mill. Plenty of comments were offered that they wouldn't work even though I explained what I was doing to deal with the possible issues. It's deja-vu all over again. (Yogi Berra)

              I will have to reconsider what I am going to post on this project. I don't feel like defending my choices, it's too time consuming.
              Free software for calculating bolt circles and similar: Click Here

              Comment


              • #67
                Originally posted by lane
                Would some one tell me why this group get so carried away over bearings.
                John's just poking fun at the Evan's claim of measuring 3 micron runout on a South Bend 9

                But once you get past the accuracy claims, it's a cool start on a lathe build.
                Last edited by lazlo; 01-02-2009, 07:25 PM.
                "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                Comment


                • #68
                  Originally posted by Evan

                  I will have to reconsider what I am going to post on this project. I don't feel like defending my choices, it's too time consuming.
                  You said it wasn't a choice, that it came out the scrap box. I just pointed out that before anybody went out to buy what is an expensive bearing that there were better bearings available cheaper that could also be used with a better design.

                  I didn't say your design was wrong, I just pointed out an alternative.

                  I have a big stack of surplus bearing here, probably about a 3 drawer filing cabinet full that have been donated over the years and there is not one double row angular contact bearing of that size or close to it, loads of Ford half shaft bearings off Cortina's at about 35mm bore which are also double row angular contact, that's the sort of use they are for.
                  So if I wanted to copy Evan I'd have to go out and buy one but as I have said many cars use two single angular contact bearings and these can be obtained for not a lot of money and make a better design.

                  .
                  .

                  Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                  Comment


                  • #69
                    Originally posted by Evan

                    I will have to reconsider what I am going to post on this project. I don't feel like defending my choices, it's too time consuming.
                    No keep going I'm trying to catch you up, you have 22,325 posts and I only have 6,804
                    .

                    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                    Comment


                    • #70
                      Originally posted by John Stevenson
                      I have a big stack of surplus bearing here, probably about a 3 drawer filing cabinet full that have been donated over the years and there is not one double row angular contact bearing of that size or close to it.
                      The standard runout for a 1" 5200 series double-row angular contact bearing is 5 tenths. Good for a home shop lathe, but a bit more than 2 micron

                      http://iksbearing.stage.thomasnet.co...t/Enggdata.pdf
                      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                      Comment


                      • #71
                        Great job

                        Evan,

                        that is a top job.

                        Congratulations on taking it on, thinking it out, making best use of what you have as well as fending off the "barbarians", "nay-sayers" and "Doubting Thomas-es".

                        As usual when "bearings" comes up, there is more "charting" and "consulting" and quoting of "learned works" than there would be at an astrologist's gab-fest.

                        All the "ifs" reminds me of the old saw that "IF your auntie had balls she'd be your uncle", and there's more "buts" than there are in ten Billy-goats.

                        At least you are having a go and getting your hands dirty instead of sitting on your freckle prognosticating and pontificating. Some won't need a bridge to get over Williams Lake - they can walk over it!!

                        Or to (sort of) quote the Bard and the Prophet - f*ck 'em!!

                        I think that Lane - as usual - has injected a lot of common sense as well as confidence in your ability and the ultimate outcome.

                        I agree with Lane.

                        I rather think that your project and credibility will come out in better shape that the credibility and egos of some others.

                        If YOUR new lathe does what YOU want it to do, then by any measure it is a total success - irrespective of the opinion of anyone else.

                        Your track record is first class thus far and I can't see you blotting your copy-book on this project or anytime soon.

                        I am looking forward to seeing it in use.

                        Comment


                        • #72
                          [quote=lane]Would some one tell me why this group get so carried away over bearings . We have all been here more than once.[/quote]

                          Because we like to tell everybody else how to do things of course
                          Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

                          Comment


                          • #73
                            Originally posted by Evan
                            Good question. I had the same sort of static over my choice to use PTFE linear bearings on my mill. Plenty of comments were offered that they wouldn't work even though I explained what I was doing to deal with the possible issues. It's deja-vu all over again. (Yogi Berra)

                            I will have to reconsider what I am going to post on this project. I don't feel like defending my choices, it's too time consuming.

                            Keep posting please! Reconsider replying maybe, but keep posting.

                            Comment


                            • #74
                              How it is.

                              Would some one tell me why this group get so carried away over bearings . We have all been here more than once.
                              Originally posted by Evan
                              Good question. I had the same sort of static over my choice to use PTFE linear bearings on my mill. Plenty of comments were offered that they wouldn't work even though I explained what I was doing to deal with the possible issues. It's deja-vu all over again. (Yogi Berra)

                              I will have to reconsider what I am going to post on this project. I don't feel like defending my choices, it's too time consuming.

                              Evan,

                              you - nor anyone else here - is obliged to answer any question as regard method etc.

                              Some may assume or believe that:
                              a. they are owed and can demand an explanation; and

                              b. that you (or anyone else) is obliged to give it.

                              They are 100% wrong on both counts as what others may believe in that regard may not necessarily be the case or true.

                              Whether you choose to or not is solely at your discretion, but having said that, I am sure that you don't need me - or anyone else -to tell you that.

                              Comment


                              • #75
                                Originally posted by Evan
                                Good question. I had the same sort of static over my choice to use PTFE linear bearings on my mill. Plenty of comments were offered that they wouldn't work even though I explained what I was doing to deal with the possible issues. It's deja-vu all over again. (Yogi Berra)

                                I will have to reconsider what I am going to post on this project. I don't feel like defending my choices, it's too time consuming.
                                No keep showing us . I like reading about what you do. beats the heck out of how do you do this are I just bought a harbor freight lathe. Besides do like i do take all of this with a grain of salt. All so no one in his right mine is going to copy what some one built because they want have the same junk to work with and they will have to improvise just like you are doing . right bearing are not.
                                Every Mans Work Is A Portrait of Him Self
                                http://sites.google.com/site/machinistsite/TWO-BUDDIES
                                http://s178.photobucket.com/user/lan...?sort=3&page=1

                                Comment

                                Working...
                                X