Re: hi-freq motors[perske etc]

>--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
>
> What???!!!!! You are going to take a standard, 3450 RPM motor and
> run it at 12000 RPM? Are you familiar with the construction of
>blast
> shields? Have you calculated the first critical speed of that
>rotor?
> I have a strong suspicion it is probably in the range of 7500-10000
> RPM. Are you aware of what happens when rotating machinery
> is operated near the critical speed? Where are you located?
> (Hopefully not near me!) Is the motor shop going to try it for you?
> Just replacing the bearings isn't going to hold this motor together!
>

Jon,
The answer in a nutshell is YES.
The motor rewinders have done this many times but without changing
the end bearings. I aim to do this to handle the side loads.
Over here in the UK we have a big woodworking concern called Wadkins.
For years they made routers with fixed head motors i.e. the motor
housing was part of the frame. They used to take standard Brooks
motors and use the rotor and stator.
The rotor had a collet chuck built in and the stator was rewound for
them.
By modern standards these were huge rotors but other than usual motor
misuse problems they ran for years.
I have rebuild loads of them.
I must state here that I do a *lot* of mechanical work on motor
repairs, probably to the extent of 35 to 40K per year.
Another thing to bear in mind Jon, is that the UK / European motors
being made now are far smaller than your American series. I had to
mod a 2Hp motor to fit an American framed machine a while ago. I got
the mounting specs off Baldor and the nearest motor I could get off
the shelf was a 3Hp model. Our 2Hp was tiny compared to the Baldor.
The rotor on this 1/2hp motor is way way less in size and mass than
the 2Hp Bosch router I have and is far more sturdy that the skimpy
wound armature that is in the Bosch spinning at 20,000

John S.