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Thread: Another Bearing ??

  1. #1
    Join Date
    Nov 2002
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    499

    Post

    Going back to the original senario, is there a plane bearing that would survive w/o pressurised oil? How hard would the shaft have to be?

    1 5/8" at 2100 is under 900 fpm, fed with an oil cup, guess that doesn't leave much for cutting forces on 50-70kpv bronze.

    just trying to think it through, maybe learn somthin

  2. #2
    Join Date
    Nov 2002
    Posts
    499

    Post Another Bearing ??

    Been reading the recent bearing posts, seen what Evan posted for Snowman about the superfinised shafts for high speed.

    Had planed a mill spindle w/ 1 5/8" shaft of 303 stainless in sintered bronze bearings. Top speed is 2100 RPM. Am I looking at trouble?

    Shaft would be just filed & polised w/ 400/600 grt sandpaper. Not heat treated. At those speeds, shouldn't be running anything but a small endmill or drill.

    Space constraints lead me away from tapered rollers.

    uute

  3. #3
    Millman Guest

    Thumbs down

    4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

    ------------------
    BFH

  4. #4
    Join Date
    Oct 2002
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    Bremerton Washington
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    "...shaft of 303 stainless in sintered bronze bearings. Top speed is 2100 RPM. Am I looking at trouble?"

    Yup.

    Spindles should be pretty hard for wear resistance in the spindle taper (above Rc 50 in most commercial machines. 303 stainless is quite soft and malleable and has an unfortunate tendancy to "fret weld." You'd be much better off using a pre-heat treated medium carbon or alloy steel (Rc 35) for this application. It's more difficult to machine but it gives excellent finishes and better wear in a plain bearing.

    Sintered bronze bearings in this size and RPM are not reccommented without pressure lube to transfer heat away from the bearing. If you're going to do that you might as well use bearing bronze. In mill spindles of the past they used bronze bearings scraped to fit with tapered journals and adjusted the diametral clearance by machining off the thrust face of the bearing to loosen it or the spindle thrust face to tighten.

  5. #5
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    Regina and Assiniboia, Saskatchewan
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    <font face="Verdana, Arial" size="2">Originally posted by Millman:
    4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

    </font>
    Attaboy Millman! Nice answer to the guys question!
    So who made you the "Grammar Nazi" around here? (You may want to check some of your own spelling in previous posts)
    I see your giving others hell about using the search function also.
    Is that because you don't know the answer...or you just want to see your name in print?
    Russ

    I have tools I don't even know I own...

  6. #6
    Join Date
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    mesa, az
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    <font face="Verdana, Arial" size="2">Originally posted by Millman:
    4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

    </font>
    Seriously you have mental problems.




    [This message has been edited by Neil (edited 03-03-2006).]
    FuQ

  7. #7
    Join Date
    Oct 2002
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    Please. Lets stick to shop problems not personalities.

  8. #8
    Join Date
    May 2003
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    52N 122W Western Kanuckistan
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    Post

    Superfinished is the term South Bend used to describe the finish on the hardened and ground spindles they made for their lathes with plain bearings and the "high speed" option.

    A highly polished spindle isn't a good idea. It needs a certain level of very fine roughness to hold an oil film on the surface. When you see specs for this kind of application they will usually specify a maximum and minimum surface finish roughness.

    Millman,

    I thought you were familiar with high precision machining. Superfinishing is a standard industry term, also called microfinishing. Try doing a Google on superfinishing.

    Here, I'll save you the trouble:

    Google superfinishing
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  9. #9
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    <font face="Verdana, Arial" size="2">Originally posted by Forrest Addy:
    Please. Lets stick to shop problems not personalities.</font>
    Second that - thanks, Forrest
    Science. If you don't understand it, don't talk to me about how it's going to end the world.

  10. #10
    Join Date
    Apr 2003
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    1,361

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    <font face="Verdana, Arial" size="2">Originally posted by mochinist:
    Originally posted by Millman:
    4 Years on this forum and you haven't read the posts? Machinists Bible ring a bell? You just want to see your name in print?You mispelled Superfinished; Explain.

    </font>
    Seriously you have mental problems.




    [This message has been edited by Neil (edited 03-03-2006).]

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