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Thread: VFD or not to D....that is the question

  1. #31
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    Quote Originally Posted by mike_kilroy View Post
    Actually quite a lot! We have worked with high speed grinders over the years: 20,30,50,000rpm... Bryant grinder used to make ones with multiple heads. We would set drive parameters based on binary coded jumpers in the big MS connector that hooked it up. We have 32 motor option, so we can program in up to 32 different motor parameter sets, and that is/was used to pick the right set for the motor in the head being swapped in.

    Today, for aluminum machining, high speed makes removing metal like using a knife on butter. It used to take around 48 hours to machine ONE airplane wing skin with typical old fashion 3-4000rpm spindles. Today, the 15-20,000rpm spindles slip thru that same metal in like 5 hours. Similar HPs.

    Why do we have 30,000rpm dremel tools?

    1.3kw @ 60krpm can remove a lot of material quickly when it makes the material almost like a liquid! Don't need so much torque for that.
    I understand the need for high speed
    but 1.3 kw >>> 40 va
    30 times as much torque

    but as was mentioned small stuff like dental drills are in the 40 va range
    most have a vfd of sorts to get 20k rpm and gearing for the rest
    The difference between stupidity and genius is that genius has its limits


  2. #32
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    quote sent to OP for standard stock drive. under $4k. no issue selling in USA as I thought.

  3. #33
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    Quote Originally Posted by Ingenieur View Post
    I understand the need for high speed
    but 1.3 kw >>> 40 va
    30 times as much torque
    I probably missed it but where did the 40VA come from?

  4. #34
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    Quote Originally Posted by Besoeker View Post
    I probably missed it but where did the 40VA come from?
    I think Ingenieur listed it in post #24 based on reading the Federal restrictions. To be controlled the device needs to exceed that size as well as have high frequency and high accuracy.

    mobile
    Last edited by GoldDigger; 01-14-17 at 09:34 PM.

  5. #35
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    Quote Originally Posted by GoldDigger View Post
    I think Ingeneur listed it in post #24 based on reading the Federal restrictions. To be controlled the device needs to exceed that size as well as have high frequency and high accuracy.

    mobile
    Appreciated, sir.

  6. #36
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    Quote Originally Posted by GoldDigger View Post
    I think Ingenieur listed it in post #24 based on reading the Federal restrictions. To be controlled the device needs to exceed that size as well as have high frequency and high accuracy.

    mobile


    Thanks
    Last edited by GoldDigger; 01-14-17 at 09:33 PM.
    The difference between stupidity and genius is that genius has its limits


  7. #37
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    Quote Originally Posted by Jraef View Post
    2 pole motor = 3600RPM (synchronous) at 60Hz. 1000Hz/60hz = 16.67, x 3600RPM = 60,000RPM. No gear box.

    I worked for Siemens at the time this all went down. The press got it wrong saying the intent was to destroy the centrifuges. The intent was to not have the enrichment work and have them flail around not knowing why and maybe give up after wasting all that money. That part almost succeeded, but what I heard that they didn't count on was the German engineers working for the Iranians not accepting that the process didn't work (possibly under threat of beheading). They apparently checked the actual speed against what the Siemens software TOLD them the speed was, then found the error and in investigating the cause of the error, found the virus in the software. Ironically the virus was introduced into the system by them. They hacked "free demo" Siemens software that they got in Germany and loaded onto thumb drives, because Iran was prohibited from buying it. Someone (likely the CIA or the Mossad) knew what they were up to and infected that free demo version of the software with Stuxnet.

    Thank you for clearing this up- I did not know that until now. But it does not surprise me because I know the press usually gets just about everything skewed.

    But, with all I read here, I had no idea the gov put limits on the output frequency Good to know too if I ever buy a VFD. Last thing I need is a fed check over a VFD I am going to take to bits (dismantle) anyway
    What is esoteric knowledge today will be common knowledge tomorrow.

  8. #38
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    Quote Originally Posted by mbrooke View Post
    Thank you for clearing this up- I did not know that until now. But it does not surprise me because I know the press usually gets just about everything skewed.

    But, with all I read here, I had no idea the gov put limits on the output frequency Good to know too if I ever buy a VFD. Last thing I need is a fed check over a VFD I am going to take to bits (dismantle) anyway
    From owner of hi speed VFD supplier yesterday: "With drives made in US and sold to US to known entities for known applications, there are no frequency restrictions."

  9. #39
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    Dyson Airblade hand dryer... its over a kilowatt at 90,000 RPM.

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