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Thread: Bronze Bushing Clearance?

  1. #1
    Join Date
    Aug 2006
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    Hesperia, CA
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    854

    Default Bronze Bushing Clearance?

    When working at small dia's the necessary rpm has my gear train just screaming. They howl so bad my family shuts the door to hear the TV. I realize they're straight cut gears and ain't never gonna be dead quiet, but I went poking around in there anyway.

    As a typical example, my tumbler gear bushings are out to .628-.629 and the shafts they ride on are .622 or so. Cheap and easy would be standard replacement .625 bushings but I wouldn't be adverse to making my own custom fit bushings to what's left of the shafts.

    Is this a worthwhile idea? If so, what clearance should I use?

    Thanx again

    SP

  2. #2
    Join Date
    Jan 2003
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    On the Oil Coast,USA
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    16,723

    Default

    .0015"

    What you have is a fairly large clearance.What about needle roller bearings and races?They can be had from Torrington with intregal seals for not much money.

  3. #3
    Join Date
    May 2003
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    52N 122W Western Kanuckistan
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    Default

    Use PTFE bushings and make them zero clearance. They will work fine at those loads and rpms. Plain virgin PTFE is good to a PV factor of 1000. The PV factor is the Pressure in psi times the Velocity in sfpm. That means a PTFE bearing will withstand 1000 psi at 1 sfpm or 1000 sfpm at 1 psi or any combination in between that doesn't exceed the value 1000. That value includes a 100 percent safety factor. The PV factor goes up two to three times if oil lubricant is used.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  4. #4
    Join Date
    May 2006
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    Default

    I made a number of bushings for my Rockwell from plain old Enco cored Bearing Bronze. Several shafts had moderately intricate features that I didn't really want to duplicate, so I just turned them a bit under, just enough to clean them up, and made new bushings to match. Easy enough and worked quite well I think.

  5. #5
    Join Date
    Jun 2007
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    830

    Default

    My Myford Super 7 Has as standard tumbler reverse gears made of Tuffnol( which was standard) When she is running on high spindle speeds pretty she is pretty silent
    Might be an idea for you to consider, for peace on domestic front

  6. #6
    Join Date
    Aug 2005
    Location
    shreveport La
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    Smile

    All good ideas. and will all work.Some times so grease will help to.

  7. #7
    Join Date
    Nov 2004
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    Kingsport, TN
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    I've wondered if there would be much difference in the noise between the stock steel gears in most gear trains versus swapping out for a couple of brass gears? What do you guys think?
    Jonathan P.

  8. #8
    Join Date
    Jul 2001
    Location
    Green Bay, WI
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    Yes...alternated brass/steel/brass will do it to.
    Rich

  9. #9
    Join Date
    Nov 2004
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    Kingsport, TN
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    Default

    Quote Originally Posted by Rich Carlstedt
    Yes...alternated brass/steel/brass will do it to.
    Rich
    Rich, would it make a big enough difference in sound to make it worth replacing a few gears in the geartrain with brass ones. I wouldn't mind trying if it would make a noticeable diffenence but hate to do it and then hardly even be able to tell they are in there. What do you think?
    Jonathan P.

  10. #10
    Join Date
    May 2006
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    Phoenix, AZ
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    Default

    You can also use "open gear grease" to quiet noisy external gears. It's a thicker, gummier grease (more or less depending on brand) that cushions and stabilizes the gear meshing. I started off using the ISO 68 on my Rockwell to avoid the (significant) mess. But then ordered some Enco spray stuff that did quiet things noticeably, though not dramatically.

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