Re: [CAD_CAM_EDM_DRO] Re: Monarch conversion to VFD

Hi Jon:
Thank you very much for that information.
The motor mounting will be a bit of a hassle, as I have to salvage the
built-in reduction gearbox from the old motor ( it's part of the front end
bell).
That part, although painful, I know roughly how to do.
Sounds like the electrical issues are not too difficult either.
That's encouraging!!
I really appreciate your help with this decision.
Cheers

Marcus

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, January 05, 2002 10:56 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Monarch conversion to VFD


> Marcus & Eva wrote:
>
> > Hi all:
> > I need some help with a decision.
> > I negotiated to buy a Monarch 10EE lathe about 4 months ago.
> > The machinery dealer was (and is) having problems getting the old DC
drive
> > to run up to speed.
> > The last 4 months have been spent making foolish promises that they are
> > unable to deliver on.
> > I have heard that several people have made a conversion to AC with a VFD
and
> > that they are happy with the result.
> > Is this a big job?? (I mean electronically...the mechanical bits I can
> > handle.)
> > What could such a conversion cost??
> > Should I consider this whole fiasco a dealbreaker? They want $10,000
CDN
> > for the machine which they say is otherwise totally rebuilt. (I've never
> > seen the machine, so at this point I'm taking their word for it)
>
> The tricky part is getting an AC motor that is in the same frame, or at
least
> something that you can adapt to fit. Apparently, in the 10EE, that is not
too
> hard, as I believe it is direct belt drive. So, you mostly need an AC
motor
> about the same diameter, with about the same shaft dimensions.
>
> Modern VFDs are really quite nice, I've got on on my mill, and will have
one on
>
> my new lathe when it is ready. If you just want to use the lathe (at $10K
CDN,
>
> it sounds like you will be!) then see if they will do the conversion.
> Electrically,
> it is real simple. You could rig up a 3-position switch, for
> forward/off/reverse,
> and a speed pot. Or, you could rig up a couple of relays and have
forward,
> reverse and stop buttons. Electronically, all you need are a speed pot
and
> the switch arrangement you prefer, wired to the terminal panel in the VFD.
> If you have 3-phase power, that's even better, otherwise just get a larger
> VFD than the motor nameplate rating, by 50% or so. (Ie. for a 5 Hp motor
> and single phase power, use a 7.5 HP VFD.) Make sure to get the heavy
> duty braking resistor, as the VFD will need to slow the lathe down and
dump
> energy into a braking resistor. If you don't have this, the VFD may
fault,
> or just take forever to stop the lathe.
>
> Jon
>
>
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