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Thread: Brass bushing question

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    CnC
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    Brass bushing question

    Can anyone tell me if they think brass bushings would be sufficient to install in a 4 step pulley that I want to use as a speed reducer on an old drill press? It presently has the typical 2 (4 step pulleys) pulleys and single v belt on a vintage Delta DP220 drill press. I want to add the third pulley and use a 2 belt system to bring down the RPM's enough to use it on metal because it's a little too fast presently. Or, should I use bearings? Thanks in advance

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    olderdan's Avatar
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    Good idea to have a speed reducer, I have planned to do the same. I would use ball races but if it has to a plain bearing use bronze or you could use needle rollers, either would need a hardened shaft and lubrication for longevity. Look forward to you posting the finished project.

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    Toolmaker51's Avatar
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    As a general material, 'brass' is not good bearing stock. As olderdan states bearing bronze has desirable qualities sought.
    Bronze bushes are available in many diameters and length combinations. The Industrial Revolution and machine age ran successfully on bronze, and many of those are still operative. Bronze stock or manufactured bushings can be modified as needed; oil grooves/ ports, thrust faces, split diameters, even adjustable. Machining, installing, and removal practices are easy. Main issue is attaining correct diameters, not only round but cylindrically straight.
    Roller components if selected for RPM and loading are good as 100%; if sizes are compatible. Shafts and housings are sleeved all the time in repair shops when they wear from seizure. Sleeves also adapt when exact sizes aren't available.
    Sincerely,
    Toolmaker51
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    If you want to sleeve it, then Sintered Bronze is the way to go. If possible buy the sleeve in a size to fit your steel shaft, and avoid reaming the internal diameter. Buy pre-impregnated with oil, or impregnate under a vacuum, and you should never have to oil it again.

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    i would put in 4 step pulley what was originally in it,,either sealed ball bearing or bronze bushing,both work fine, the SBB of course doesnt need a shot of spray lube (NOT WD-40!!!!) once a week when u use drill press,,since the BB is going to drip lube down, look and see if that will cause a problem..is this pulley asian??? if so it may need a metric OD bushing,hard to find ,and u might have to make it..turn OD to fit pulley, install in pulley, then fit pulley in lathe, and ream or bore out bushing..also if installing BB u will need some way of keeping pulley in place, from moving up or down,tension from belts may not be enough to keep pulley in place,,If using SBB a light to medium press fit should keep pulley in place.,if pulley had SBB,its not hard to find replacement bearings,larger towns have bearing distibuters,,or u can always get them off e-bay, once u know the sizes(OD, ID,and thickness)..in smaller towns go to the old shops that rebuild alternators and generators for vehicles, they carry plenty of SBB in different sizes.
    Last edited by madokie; 12-04-2018 at 11:04 PM.

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    Quote Originally Posted by Moby Duck View Post
    If you want to sleeve it, then Sintered Bronze is the way to go. If possible buy the sleeve in a size to fit your steel shaft, and avoid reaming the internal diameter. Buy pre-impregnated with oil, or impregnate under a vacuum, and you should never have to oil it again.
    Absolutely. Sintered, like casting isn't dense like rolled material. Reaming. closes off most of the pores [burnishes], blocking capillary action needed to convey lubricant. Even boring, a little too much radius in cutting edge pushes swarf in pores.

    I don't have easily accessed fan motors in my home heating furnaces. They don't seem to add oilers anymore. In 15 years, 3 ate their bushings...winter time no less.
    This weekend I'm pulling one to replace. Thinking about machining new end bells with decent sealed ball bearings. Might have to sleeve to a standard ID, width less of an issue. If so, I'll dowel two discs, clamped by same holes holding motor together, and bore bearing housings. Ends get block off plates.
    I shouldn't have to look at them ever again. Ever?, thank you!
    Sincerely,
    Toolmaker51
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    Most drill presses having those intermediate pulleys usually only have the pulley supported from below on a movable pivoting shaft that allows for different belt lengths depending on what primary and secondary pulleys are selected. A single bush, (of any type) wont handle those lateral forces. A ball/roller bearing is required, unless you have the means to support it from both sides

    cheers Phil


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