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Thread: Making 85-5-5-5 brass

  1. #21
    Senior Member Robert's Avatar
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    I made this today. This particular top spins forever:



    R
    "Whether you think that you can, or that you can't, you are usually right."
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  2. #22
    Numb (dumb?) Question: does this alloy make 'passable' bearings/bushings? As in "could I cast bushings with built-in mounting flanges, given suitable raw materials?"

    Note that alteration of the mixture is acceptable, i.e. less zinc / lead and more tin. Note also that I'm not picky beyond 'it shouldn't be a complete headache to cast or machine, and work *passably* as a bearing, too.'
    Ouch! That stuff's hot!

  3. #23
    den, I took a quick look at some of Ammen's mixes and the closest to the 85 triple 5 is bearing bronze at 80 copper and 10 each of lead and zinc, or journal bronze with 82-84 copper, 12-14 silicon, 2-4.5 zinc and less than 1 of lead and iron.
    I have no idea as to the ease of casting.
    If you think you can't do it, you're right!

  4. #24
    Senior Member Robert's Avatar
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    I'm pretty sure you could make and cast any bearing alloy you wanted. There may be a little porosity but that should not hurt a bearing at all. I have cast bronzes with Cu content ranging from 65-95%. I have used various alloying metals.
    C932 bearing bronze is very close to what I made here:

    Bearing Bronze (C932), a/k/a SAE 660
    Minimum Properties Ultimate Tensile Strength, psi 35,000
    Yield Strength, psi 20,000
    Elongation in 2" 10%
    Brinell Hardness 65

    Chemistry:
    Copper (Cu) 81.0 - 85.0%
    Tin (Sn) 6.3 - 7.5%
    Lead 6.0 - 8.0%
    Zinc 2.0 - 4.0%

    Robert
    Last edited by Robert; 04-19-2017 at 02:50 AM.
    "Whether you think that you can, or that you can't, you are usually right."
    - Henry Ford (1863-1947)

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  5. #25
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    One question you have to consider is the speed of the shaft in the bearing. Having been in the old time wooden boat building business when I was younger, I had to pour bearings for my machinery sometimes, most of which ran using wide flat belts on two inch shafts run at a fairly low speeds. Damn near any bronze or lead/tin alloy did fine for that. If you are running a small shaft at 3000 rpm, the requirements are more particular. You want a tin bronze with some lead in it, or a Babbitt metal with a lot of tin.

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

  6. #26
    Senior Member Robert's Avatar
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    Good points. Also, some bearing are sintered and oil impregnated.
    Robert
    "Whether you think that you can, or that you can't, you are usually right."
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  7. #27
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    And there are some definite disadvantages to each: Babbitt and bronze.
    • Bronze is cheap. Maybe three dollars a pound, but more difficult to pour and to machine.
    • Babbitt is costly (tin is around 20 dollars a pound, and it takes more pounds for a given volume), but it is easy to machine by hand for a perfect fit.


    R
    When I die, Heaven can wait—I want to go to McMaster-Carr.

  8. #28
    'Bearing', as in a hand-turned/twisted 1/2-10 acme thread turns in it (as a nut), as part of an ersatz right-angle welding clamp (which normally goes for $$$$, if one wants to buy store-bought ones. If one wants 'several' - in our case, eight of 'em for the group's use - the tariff could easily kill a k-bill, i.e. over a hundred PER item, gack!)

    Note: main castings for the eight are done, and want machining time. The large mill is somewhat lacking in the clamping department, hence tooling needs making first!

    Note 2: the current drawing showes a #60 drill hole for 'oil'.

    Basically, I was 'after' a half-baked version of #660 bronze - half-baked as in 'he was using a lot of scrounged materials for the ingredients, and wasn't being especially careful about the formulation'. Then again, I doubt this is an arduous aplication...
    Last edited by den; 04-29-2017 at 05:15 PM. Reason: Original needed clarification
    Ouch! That stuff's hot!

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