Re: [CAD_CAM_EDM_DRO] CNC mill DC motor field wiring

The other thing to watch with low field conditons is flashover on the
brushgear - festive (much light and sound) but dangerous and destructive. I
would limit the field voltage variation to no more than half rated value and
some may feel that is overgenerous.

Regards Peter

----- Original Message -----
From: "Brian" <ka1bbg@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, December 14, 2002 12:50 AM
Subject: Re: [CAD_CAM_EDM_DRO] CNC mill DC motor field wiring


> Hi, watch out if you get the field too low in voltage the armature can
draw
> huge quanities of current and do speed run-a-way. Its one way to get more
> rpm but one has to watch armature current carefully. Playing with the
field
> voltage is a good way to get hurt and destroy equipment. be careful! cul
> brian f.
> ----- Original Message -----
> From: <skykotechnologies@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Friday, December 13, 2002 11:24 AM
> Subject: [CAD_CAM_EDM_DRO] CNC mill DC motor field wiring
>
>
> > I finally got around to installing a 5HP 4 quadrant regenerative
> > drive (from KB) on my shizuoka B3V mill. I didn't really know the
> > specs on the motor, except that it is a 5HP DC motor, so I figured it
> > was probably 180V armature, 200V field. The old broken spindle
> > driver was labled 3.7KW DC motor speed control model 1-4064 by Sanyo
> > Denki Co.
> >
> > Anyway, it works just fine, except I don't know if it is rotating as
> > fast as it was designed. The field resistance is about 116 ohms, so
> > I figured it had to be 200V. Would it hurt things to run it at
> > 100V? I guess it is going to give reduced torque and double? the
> > speed, which might be too much for the bearings.
> >
> > Any idea what the designed max rpm on this mill is? The old fanuc
> > control panel had an analog spindle speed meter that has about
> > 3500rpm and 740rpm as the max meter movement. That makes sense as
> > the mill has a geared head with a 5 or 6 to 1 ratio (haven't actually
> > bothered to measure the ratio yet). I would estimate the motor is
> > spinning much slower than 3500...perhaps 1800 or so.
> >
> > I just got a 240VAC 9.5 amp autotransformer at an auction, so I
> > guess I could easily build a variable field voltage generator with
> > the addition of a small bridge rectifier....
> >
> > Thanks for any ideas or suggestions,
> >
> > Richard
> >
> >
> >
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> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
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>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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