Re: Values for Calulating Motor Sizing

Jon, this is exactly the information I was hoping for. It looks like
a 600oz motor will work with a Bridgeport type mill. Thanks again, I
appreciate it.
Mark

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
>
>
> natchamp_87 wrote:
>
> >I "think" (bad, I know) I have an idea of the motor size I need
for a
> >BP retrofit but would like to calc it out to see. I have read
> >numerous archives, especially the infamous # 45509 from Mariss.
That
> >is very useful. However, I don't have a good feeling for the
input
> >values of IPM and Lbs.
> >
> >What would be a low/med/high IPM for a CNC milling operation?
> >
> For actual milling, 30 IPM is about the highest I've done with a
> Bridgeport. But, you also
> want a decent rapid feed, at least 60 IPM, to move around from
place to
> place, or when setting
> up, etc. Even 120 IPM would be nice. Unless you are doing serious
> production, anything over
> 120 IPM is not likely to be needed.
>
> > I will
> >be mosting doing aluminum with some steel. What IPM is slow, fast,
> >etc. I'm shooting in the dark at this point.
> >
> >
> Heavy milling in steel might be more in the 6-10 IPM range,
depending on
> whether you are
> using HSS or carbide cutters. Flycutting in steel might be down
near 1 IPM.
>
> >What is a good Lbs value? Is this suppose to represent the weight
of
> >the table or force required to move the table while cutting, or
> >both?
> >
> This is the linear force required to move the work into the cutter
on
> the worst cut you can
> think of. Obviously, if your motors stall out on a practical cut,
it
> can be a big problem.
>
> I did some VERY back of the envelope type calculations, once, for a
1/2"
> end mill at fairly
> low speed, cutting something hard. I figured that the cutting
forces to
> stall my 1 Hp spindle
> motor would amount to something like 500 Lbs of linear force. To
> provide some safety margin,
> I figured I wanted 1000 Lbs of linear force, to accomodate losses,
> friction, etc.
>
> Jon