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  • #49504
    david pierce
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    A couple of Levin Lathes are up for sale on Ebay. is a cone bearing lathe for $325 buy it now and the other is which is a ball bearing lathe up for bid.

    #62123
    chris mabbott
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    David, which one of the two would you say is the most accurate, the BB or cone type :?:

    #62124
    david pierce
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    Chris,
    Believe it or not large industrial lathes used to have cone bearing spindles. These lathes were great machines in their day but all of them were phased out with ball bearing machines. Cone bearing machines ruled the day until ball bearing manufacturing produced machines that surpassed the quality of the cone bearing machines. This happened around the end of World War II. In the early 1950s Derbyshire produced a small watchmaker lathe that finally surpassed the cone bearing design. The ball bearing spindle can turn faster, more accurately and generally last longer than a cone bearing spindle. Cone bearing watchmaker lathes represent the last holdout of a bygone era.
    david

    #62125
    chris mabbott
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    The reason I ask David is becouse my Marshall lathe is a BB type, it runs very quietly and smooth like a brand new highway..
    I have 2 Boley lathes, an 8 & 6mm that have the cone type, they tend to run warmer, obviously due to more friction, I believe that at times, this is due to an airlock in those old style oil drip feeders, so the oil simply sits in the feed hole until I break the bubble..
    The Marshall, by comparison, does not have this issue, due to its design, and the bearings do not cause a lock since their action draws the oil inside. When I use it for heavier work, it doesn’t even get warm..

    I might just start using a zirk and pump in a bit of high speed/temp synth grease on the cone models, not as messy as oil and it should stay put a little longer..

    #62126
    david pierce
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    Chris,
    Grease between the bearing surfaces may not give you the result you want. The basic idea of a cone bearing is to have a small distance between the bearing surfaces. This is your runout and there must be some runout of the spindle will not turn. I like hydraulic oil the best but whatever you use must be thin enough to go between the friction surfaces. A cone bearing spindle needs to run slower than a ball bearing spindle which is why it is heating up; but you already knew that.
    david

    #62127
    chris mabbott
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    David,

    I hear ya buddy, I was thinking along the lines of the air lock problem that was causing the heating issue. I’ve tried adjusting the runout on the spindle to various positions but those drip feeds still seem to resist performing their job. Soon as I poke something in the hole, it’s ok, for a while. All is clear and unobstructed, so no issue there..
    So the oil not being constantly supplied to remove the heat is also part of the problem.. although they work well, when they work, they are designed to leak out oil, and that is messy when dealing with our stuff. So I’m looking for a viable alternative..

    I’ve been using the SKF bearing grease for the Marshall (excuse my mix up earlier when I said oil 🙄 ) which is a decent product and available in the EU.

    I was looking at their oil based low viscosity grease that might prove a better alternative?
    It’s not a huge issue as I use the 6 as a polishing rig and the 8 rarely, the Marshall lathe has spoiled me, which, IMHO I feel is a far better machine & more… forgiving of operator error ;)

    #62128
    david pierce
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    Chris,
    Grease is essentially oil to which thixotropic additives have been added. If the physical size (micorscopic) is larger than the clearance between the two surfaces, the lubricant cannot enter where it is needed. This is why a tinnner lubricant is needed. The trick is to have the proper viscosity to do the job. Believe it or not there is a science called MICROTRIBOLOGY that studies these matters. The reason grease works on extreme precision ball bearings is because there is a space between the balls. The thickness of the grease allows it to stay in one place better than a thinner product.
    david

    #62129
    david pierce
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    • Topics Started: 90
    • Total Posts: 1360

    Chris,
    By the way the most accurate spindles use air and hydraulic bearings. Hydraulic bearings are used on centerless grinders. The hydraulic fluid is pumped between the two surfaces and the accuracy is determined by the physical size of the molecules of oil between the two surfaces. Air bearings can produce the most accurate spindles due to the small size of the air molecules.
    david

    #62130
    chris mabbott
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    • Topics Started: 119
    • Total Posts: 1525

    Big D, I thought microtribology was the study of pigmy tribes in Africa 🙄

    #62131
    willofiam
    Moderator
    • Topics Started: 75
    • Total Posts: 1437

    Thought I would throw this in here too. I have a Schaublin 70 that has the cone bearing with a front thrust bearing, the owners manual says “Oil contained in the reservoirs rises to the top of the tubes by capillary action and thus dripping onto the bearings ensuring constant lubrication” This type lathe has a tube in the reservoir for the oil, it continues to say” Never pour oil into the tubes” that is the smaller tubes in the reservoir, and “To great a flow will cause harmful overheating of the bearings” and “Above all avoid using grease” “use preferably a good mineral oil with a viscosity of about 3’E at 50’C (122’F)” Anyway, may give some ideas here. Have a great day, William

    #62132
    arutha
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    @Chris Mabbott wrote:

    Big D, I thought microtribology was the study of pigmy tribes in Africa 🙄

    I though “Big D” were a brand of peanuts?

    Paul

    #62133
    david pierce
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    • Topics Started: 90
    • Total Posts: 1360

    Fortunately I am just average “D”.

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