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  1. #21
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    Quote Originally Posted by RonRock View Post
    Spell check. Gotta pat attention.
    Levity brake. Keep your hands off my tent shun. It's an endangled speech ease.

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    Quote Originally Posted by RonRock View Post
    I'm now looking for a 5HP 3 phase motor as my next build. I have a better understanding of the way RPC's function and I would like to quiet down the idler motor.
    I used a 5Hp then scaled down to a 2Hp for a BP mill. No difference noticed except the sound of silence.
    Last edited by rons; 07-17-2019 at 08:34 PM.

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    Quote Originally Posted by RonRock View Post
    ...would like to quiet down the idler motor.
    Many of us, the noise is "lost" - no longer noticed once the machine gets to work. Some move them other side of a wall, or even outdoors to a shed or bespoke "RPC doghouse".

    Actual "at-source" sound reduction is easily said - use a "TENV" (Totally Enclosed, Non-Ventilated) type of motor for idler.

    DOING that is harder. They aren't all that common, used, in sizes over fractional to one or two HP, nor at all "cheap" bought new, any size.

    My one is about as loud as they get for its size. Weg 10 HP idler is economy-grade, drip-proof only, not sealed, and with a fairly noisy fan.

    BFD.

    Cheaper to buy more wire and "remote it" other side of TWO walls, than to mess with acoustics & such.

    2CW

  4. #24
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    Quote Originally Posted by RonRock View Post
    Thank you rons. I will do that. I was wondering if that Cpf capacitor was needed. It didn't change my voltages much and only slightly changed the Line In amps. I like the first set of numbers better than the others also.

    I'll do as you suggest and load test. Trouble is that my biggest load at this point is my 1 1/2 HP Bridgeport. I also have a surface grinder, but I think that it is only 1 1/2 HP also.

    I built a 7 1/2 HP RPC because that is what I had to start with. The reason for the balancing questions is that at this point I have everything mounted to a piece of plywood. I'd like to get things reasonably in the finished order before drilling and mounting in my enclosure. As you probably know the enclosure is the most expensive part of the project.

    But as well as that I would really like to have a better understanding of how these things work.


    Thanks guys for the guidance.

    I'm now looking for a 5HP 3 phase motor as my next build. I have a better understanding of the way RPC's function and I would like to quiet down the idler motor.
    The enclosure cost can be reduced by buying a used box. There will probably be holes. So what. I use scrap metal sheet of the same thickness and turn circular wafers and tack weld them in the unwanted holes. A little filing, filling, and paint and the box will look new.

    As for the motor. This is what I did to a used Baldor 5Hp motor that vibrated a bit too much. Put the rotor on a lathe and machined off the aluminium stubs sticking out that was a result of the casting blank. There were a lot of irregular Then I skimmed the lathe cutter bit across the entire rotor. It was not even to begin with. I did take off much metal because I didn't want to increase the air gap. Then I removed the putty that was used for balancing. Removed the rotor and mounted it on V blocks. Performed a static balance with two sizes (an weights) of small nuts that could fit on the circular projections on the circumference of the rotor (both ends). When it looked good I used some high grade epoxy to fix the nuts in place. All the time thinking that this was not going to help that much but I might as well do what I can. The result was that the 5Hp motor is now quieter and vibrates much less than a new 2hp motor (both are 1725 rpm).

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    Some of those "stubs" may have been for balancing.... On mine, I stacked washers on the stubs to balance, and riveted the stub over to hold them. That's how the factory did it..... so I just followed suit. Balance was off due to a cast-in fan/heatsink blade having broken off

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    Quote Originally Posted by JST View Post
    Some of those "stubs" may have been for balancing.... On mine, I stacked washers on the stubs to balance, and riveted the stub over to hold them. That's how the factory did it..... so I just followed suit. Balance was off due to a cast-in fan/heatsink blade having broken off
    The stubs were from a mold. Just little burrs where the steel laminations and aluminium joined. Along the circumference on each end of the rotor there are dowel like projections about 3/8" long. Those are the places I epoxied the nuts. The projections where about 1/4" in diameter and I could screw the nuts on and make a small thread. But I used epoxy too. The original balance putty from the factory looked like a wad of bubble gum.

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    Default Filling KO holes

    Quote Originally Posted by rons View Post
    The enclosure cost can be reduced by buying a used box. There will probably be holes. So what. I use scrap metal sheet of the same thickness and turn circular wafers and tack weld them in the unwanted holes. A little filing, filling, and paint and the box will look new.
    I use a similar method, for years now. But instead of cutting used blanks to fit, I save old ones. Any box headed to the scrap bin gets harvested. Makes for a faster patch and grind.

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    SAF Ω


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