I agree, BUT. As nice as VFDs are, they are expensive. Cheaper options
would be to build a rotary phase converter or buy or build a static
converter.
I built a rotary years ago, they aren't that hard. Plenty of good info
around free on the web. I had to sell it when I moved, just too much
weight in the trailer along with everything else. I now use a static
converter with good results. I use one converter on two machines.
On 9/9/2010 8:08 AM, Jim Ash wrote:
>
> What he said.
>
> Also - Having a VFD opens up possibilities for you that others avoid.
> Lots of folks won't give a piece of 3-phase equipment a second look
> because it's 3-phase. This attitude has caused lots of really nice
> equipment to sell for somewhere between scrap and get-it-out-of-here
> prices. Bad for the 3-phase phobic; good for you.
>
> In a one-man shop, size your VFD for the largest piece of equipment
> you plan to run on it.
>
> Jim Ash
>
> -----Original Message-----
> From: CNC 6-axis Designs
> Sent: Sep 10, 2010 7:24 AM
> To: gingery_machines@yahoogroups.com
> <mailto:gingery_machines%40yahoogroups.com>
> Subject: Re: [gingery_machines] Repowering lathe
>
> The smaller motor will work, but DONT DO IT!
>
> For less money, you can get a VFD that makes the 3-phase from whatever
> you have (110, 220, 50 hz, 60 hz etc.).
> The model is the Hitachi 2xx, 2.2 kW size. About 400$. (I have one on my
> Bridgeportr M-head spindle on my shop-built milling machine).
>
> The 3-phase motor is VASTLY superior to a ANY single phase solution
> apart from indexed servo spindle (which I also have).
>
> If you buy the smaller motor you then ideally need a speed control for
> it, which is extremely useful on a lathe. At least a contactor (you need
> one for lathe use) and that will be 50-100$ on its own.
> To get the VFD, go to automation direct, drives warehouse, etc.
>
> Look for one that eats 220 (if you have it) and outputs the 575v.
> The docs are good, and will get you going.
> There are a lot of very useful things in a VFD that only exist in VFDs
> (and servos) you simply cannot get any other way. Included in the same
> price.
> Dynamic braking, holdng, soft start, ramps, PID loops, safety features,
> forward and reverse, WITH automatic safety features, overload overheat
> protection etc etc.
> All of the above are included in the Hitachi I used, and all work on my
> CNC milling machine, with about 5 control wires and 2 days setup time in
> the VFD.
>
> Safety is important. VFDs come with all the safety features as standard,
> things like not getting the spindle to run at last (full) speed in an
> error, overload, overheat, power-out situation.
> VFD driven 3-phase motors also give a much better surface finish, when
> you have a good heavy lathe behind them (I do).
>
> My lathe is currently running with an original factory 1.5 kW industrial
> motor, and I am swapping it for a servo (indexed) spindle.
> I am now fixing the swarf guards on the mill, to face mill the mounts
> (30 mm steel flat bar F114), to permanently install the servo motor
> mount on the lathe.
>
> > I have been lurking for several years and have cast the gingery bed in
> > aluminium but then stalled. Have cast a few other objects as I
> > needed them but have always wanted to play with a lathe since taking a
> > metal working class at school back in the 1970's.
> > I just lucked out and ended up with a Harrison 300 metal lathe which
> > has a 3-phase 575volt 3Hp motor driving the spindle. I need to convert
> > to a single phase motor. A 3hp motor with the same frame size will
> > cost about $600.00 but I found a 2hp motor for about half that. The
> > question is-Will a 2 Hp motor give an adequate level of performance
> > for home/ hobby use considering that the lathe has a spindle gear
> > range of about 48rpm up to 2400rpm? The lathe is a 61/2inch (13 inch)
> > by 24 inch size.
> > I have absolutely no experience running a lathe but I suspect the
> > smaller motor will work but will limit the size of cut I can take. Is
> > that correct?
> > Thanks for any input.
> > Cliff Swan
> >
>
> [Non-text portions of this message have been removed]
>
>
--
Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
Sometimes you just gotta do what makes you smile.<GRIN>
http://www.plansandprojects.com My hobby pages are here:
http://www.plansandprojects.com/My%20Machines/
Visit the castinghobby FAQ:
http://castinghobbyfaq.bareboogerhost.com/
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