Re: [CAD_CAM_EDM_DRO] Re: Stepper motor speeds

Tim,
I guess it's my engineering background that makes me want to plug all
the components into a formula, and come out with an exact answer. The mill
I'm going to convert, is a full size Enco, about the size of a Bridgeport, 1
1/2 HP variable speed motor, 8" X 36" table, and driven by a VFD. I'd rather
oversize the motors, and have some torque to spare, but I was just trying to
save a little space on the quill feed, by using a slightly smaller motor.
Thanks for the direction.

Marv Frankel
Los Angeles

----- Original Message -----
From: "Tim Goldstein" <timg@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, November 03, 2002 2:13 PM
Subject: RE: [CAD_CAM_EDM_DRO] Re: Stepper motor speeds


> It is not as easy as just looking at a particular metal and getting a
> required speed and cutting force. As an example, if I cut a piece of
> aluminum on my Bridgeport with a 1-1/2" 4 flute carbide insert cutter I
> may use a feed of 50 ipm. If I cut the same material on my Sherline with
> a 1/4" 2 tooth HSS cutter 10 ipm will be more appropriate. Not only are
> the speed vastly different, but so are the required forces. So, it is
> not just material but also how much horse power you have, how rigid the
> machine is which will limit the size of a cut you can take, etc.
>
> While you can take the engineering approach to this and calculate
> everything a much easier approach is to just follow what others have
> found to work. If I remember correctly you are setting up a mill/drill
> or a Shoptask? If so just use some low inductance NEMA 34 motors in the
> 400 - 600 in/oz range and you will get great performance that is in line
> with what the machines capabilities are. Lots of us have done it and we
> know it works. Now if I was designing this to produce a number of these
> machines I would get a lot more worried about actually calculating it
> all out so I could better understand where I can save a little.
>
> Tim
> [Denver CO]
>
>
> > -----Original Message-----
> >
> > Dave,
> > Thanks for the information, and the reference to
> > Mariss's message. I can understand most of it, but his
> > reference to "push" has me a little confused. The formula for
> > "push" is clear enough, but how do you figure out how many
> > inches/minute or pounds are required? Don't both factors vary
> > with the material being milled? If that's the case, it would
> > be helpful if someone posted a chart with the speed & lbs.
> > for various materials. It might help me to make an
> > intelligent decision.
> >
> > Marv Frankel
> > Los Angeles
>
>
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