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  1. #1
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    Default static phase converter.

    I have a Kent surface grinder ( no hydraulics) and finally got around to check out the motor on their web site and it is listed as about 2 5/8 Hp (converted). 220 volt. I always figured it was about a 1 hp. Anyway I have been running it off a 1 hp static converter.

    Freebe from a friend way before I bought the grinder. It wouldn't start my Tree mill and I bought a 3 hp rotary for that.

    The converter clicks a few times as the wheel is ramping up. Slow start didn't seem like a bad thing. Am I risking burning out the motor by under powering it. Would it run smoother of the rotary?

    I can hook it to the rotary but the run noise is annoying. I have it sitting on styrofoam. Might have to rewire and move the rotary outside the shop.While it was under warranty I didn't want to install a remote start switch, but that isn't a problem now.

    Accustomed to a grinder at work,so I had to have one at home too. My run time is probably 10 hours a year. Any more than that and I would spring for a hydraulic.

    Dave

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    Under the circumstances, I would seriously think about a VFD. They are quiet, true 3 phase and well within your power requirements particularly if you have 230 single phase. They offer other benefits also, ramp starting and inherent over load protection. and small.

    Tom

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    Quote Originally Posted by winger View Post
    I have a Kent surface grinder ( no hydraulics) and finally got around to check out the motor on their web site and it is listed as about 2 5/8 Hp (converted). 220 volt. I always figured it was about a 1 hp. Anyway I have been running it off a 1 hp static converter.

    The converter clicks a few times as the wheel is ramping up. Slow start didn't seem like a bad thing. Am I risking burning out the motor by under powering it. Would it run smoother of the rotary?
    You already know that this is not the right thing to do. In addition you will not get the full power out of the grinder and/or the surface finish might not
    turn out so great sometimes.

    A well built RPC quiets down when the load starts. You know you have won the RPC noise war when the target machine is louder and you put on the headphones anyway.
    I suggest you do not use the static (1hp) to run the grinder (2.625 Hp). Instead try to make things quieter.
    - static balance your RPC idler.
    - eliminate sheet metal vibration if the RPC electrical enclosure is mounted to the idler.
    - Cover RPC idler with a wood box.
    - use a thick rubber mat instead of Styrofoam.

    A VFD is a option but you might have to modify the wiring to the grinder motor.

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    The rotary was from a company in Texas that makes them. Can't remember the name.
    The capacitors should have been balanced, but maybe not. the capacitor box is mounted to the motor. I'm in the process of moving the machines around, took out more of the garage, so I have to rewire anyway.
    Thanks

    Dave

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    I would add about 30 or 40 mfd run cap in parralel with the one already in the static convertor, and maybe 100 mfd more in parralel on the start side. I get my caps from a local scrapper, they cant go with the scrap loads. He gives me 5 gallon buckets full at at time. Gives lots of options for this kind of tuning.

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    I'm going to try and wire back up this weekend. I'll see if the grinder runs better on the rotary.

    thanks for the info

    Dave

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    Quote Originally Posted by winger View Post
    The rotary was from a company in Texas that makes them. Can't remember the name.
    The capacitors should have been balanced, but maybe not. the capacitor box is mounted to the motor. I'm in the process of moving the machines around, took out more of the garage, so I have to rewire anyway.
    Thanks

    Dave
    Styrofoam is even used for planar SPEAKERS. Might grab a gain with an ignorant Dollar Store recycled rubber doormat. Better solutions, yet, exist, but rigid foams are not among them.

    It's sumthin' "resilient" - kinda "gummy" even, that absorbs sound by converting motion into heat yah want.

    Internet is chock full of sound management lore. PM just ain't where much of it it hangs-out.

    Read-up on "green glue" for a sampler, add a baffle or two, move the RPC, and it can go right off yer lst for annoying noise to the point you mebbe want a pilot light in the bedroom to remind you yah left it running when you broke for dinner!

    "Static" converters do not. Convert. They only trick the motor into running badly crippled instead of refusing to do outta common sense and a sense of self preservation. Well.. Ok. They convert a wise motor into a stupid one, then?

    Ones less evil, yah just add an idler and they become an RPC starter/balancer controller - are no longer dangerous junk.


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