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Tapered bronze bearings?

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  • Tapered bronze bearings?

    I came across a description of an interesting bearing design, and was wondering if anyone has seen one or knows where to find more info on it. It's a bronze bearing that has a parallel bore for a shaft, and has a tapered od and is split lengthwise. The idea is that the outer bore for the bearing is also tapered, which allows you to adjust the clearance to the shaft by squeezing the bearing via the taper. When I search for tapered bronze bearings all I get is cone bearing info.

  • #2
    Tapered Bushing

    In the late 1950's / early 1960's, I had an old Sears lathe with a bearing like the one you describe. I remember because I bought a new bearing and spindle from Sears and replaced it. This was a small lathe of about 4-6 inch size with about a 3/4 inch shaft diameter with a very small bore. I did not keep it long.

    I don't remember whether it was Craftsman or Dunlap brand. Sorry but that is all the info I have. You might find some information on an Atlas site.

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    • #3
      A great design for a small low speed spindle. A hardened shaft running in a proper alloy of bronze can be run at a very close tolerance. Easily adjusted for wear.
      Gene

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      • #4
        Originally posted by topct
        A great design for a small low speed spindle. A hardened shaft running in a proper alloy of bronze can be run at a very close tolerance. Easily adjusted for wear.
        Lots of older machines were this way, particularly Hendey, both lathes and millers.

        allan

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        • #5
          Not doubting you but I am wondering about the taper...am I missing something? What is the need to have a taper (of course if the part/casting around the "sleeve" is tapered, it makes sense the bearing is as well, but...).

          The idea of squeezing a split bronze bearing and so adjusting clearance is/was pretty common for a whole bunch of lathe manufacturers, many decades ago but as far as I know, they were not tapered on the exterior. OTOH, I am making an assumption, since I have never completely removed one out of its housing (my Sheldon lathe is this way and I wish it weren't but rather a true bearing cap style)

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          • #6
            But as it's adjusted, the radius of curvature of the bearing ID would need to change in order to remain perfectly concentric with the OD of the shaft ...would it not?

            Or is the idea that the difference is so miniscule as to be insignificant?
            Lynn (Huntsville, AL)

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            • #7
              This is where it is used:

              http://www.youtube.com/watch?v=d-woPRV_lac

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              • #8
                The ones I'm familiar with have a dove tail milled in the slot, and a threaded nut on the small end, loosen up the dove tail nuts then adjust the bearing and the snug up the dove tail nuts, then run it and check to see if you got it right, not to tight and not running hot. One thing I forgot to add was they use square threads so the angle of the thread does not squeeze the bearing in.
                Last edited by duckman; 02-14-2012, 02:03 AM.

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                • #9
                  A long time ago---

                  I owned an ancient IXL lathe made in Germany. That had this type of bearings. It was very worn and the adjustment was tricky, but once correct the lathe worked well and would part off smoothly. Regards David Powell.

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                  • #10
                    It's used on Holbrook lathe spindles (those that aren't the roller bearing ones, of course), a large adjusting nut presses the outside-tapered bearing into a tapered housing in the headstock, adjust until tight then tighten the wedge in the gap to establish clearance - works very well indeed, can run up to 2000 RPM (more if pushed) with barely measurable runout, no cyclic roller noise - with a properly sharpened tool they can take cuts that look like cylindrical grinding, though the rigidity of the machine probably helps!

                    One word of advice if trying this at home - Holbrook recommended ISO-5 hydraulic oil for the spindle bearings, which is mighty thin stuff, and had pumped lubrication for the spindle...

                    Dave H. (the other one)
                    Rules are for the obedience of fools, and the guidance of wise men.

                    Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

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                    • #11
                      This type of bearing was also used on various Brown and Sharpe grinders. The bearings could be tightened to take up wear. In the mid 1990's I worked in a shop that had several Brown and Sharpes, one of which was alt least 90 years old. We ran 10 and 12 inch diameter diamond wheels on them at about 2800 rpms. We had to have the bearings on one of them scraped because of scoring. After that it ran fine until the company closed.
                      North Central Arkansas

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                      • #12
                        This idea fascinates me...with one exception (that may not have been as "miller" was not specified...) the spindles have been horizontal in orientation.
                        Is there any reason, a vertical spindle of a similar design would come to grief?
                        Or would any issue be more based on keeping it properly lubricated? [I am thinking bath/near immersion as opposed to pressurized from a pump]

                        Full disclosure: right at this moment one of the things going around in my brain is a vertical head for an Atlas milling machine and it appears to me that its the $$$ bearings that account for a goodly portion of the bill...

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                        • #13
                          The biggest issue is the necessary slot, which would leak oil continually..... you would need to come up with an oiling scheme that would contain the oil and possibly recirculate it via a simple scoop arrangement, etc.

                          The small Sears lathe referred to above is the "109", of which at least the 109.20630 has the exact setup described. I line-reamed one to very good performance (of the bearing) many years ago, and then got rid of it.

                          In those the issue was not "egging" of the bore, but "bell-mouthing". no amount of tightening fixes that, you have to line-ream/line bore the bearing to size.
                          CNC machines only go through the motions.

                          Ideas expressed may be mine, or from anyone else in the universe.
                          Not responsible for clerical errors. Or those made by lay people either.
                          Number formats and units may be chosen at random depending on what day it is.
                          I reserve the right to use a number system with any integer base without prior notice.
                          Generalizations are understood to be "often" true, but not true in every case.

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                          • #14
                            This type of bearing was used in the horizontal mill arbor supports made by Cincinnati and by Kearney and Trecker.

                            Suitable ball or roller bearings in a vertical head for an Atlas milling machine should be available at very reasonable prices. The big expense comes with large high precision bearings used in much larger and more capable machines.
                            Don Young

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                            • #15
                              The early Rockwell Toolmaker surface grinders use a large tapered bronze bearing in the front. There is a oil pond below the spindle that a slinger ring rides in to pick up oil. The spindle speed with the standard 1725 rpm motor was 3200 and 4200 rpm, so they can handle some speed with the right oil. Mine runs smooth and quiet and was not too difficult to clean up the bearing surfaces.

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