you can wire 220 with or without a neutral. To save you some time, I
use Leviton 2711 plugs (and matching receptacle) - this is a 4 wire, 2
hot, ground, neutral arrangement. There is another 4 wire plug that
has 3 hots, don't use that one. These are available from a nice
seller on e-bay for about half of retail, by the way.

Having neutral at the machine is advantageous for me because then I
can have an outlet there for a lamp or other accessory that wants 110
and not have extension cords on the floor to trip on.

If you would rather not have neutral, you can use a circuit with a
second relay.
this link provides a sensible and clear approach
http://www.homemetalshopclub.org/pro...nv/phconv.html

there are other sites with some rather "ad hoc" and somewhat
nonsensical approaches.

if you would like the schematic for the two relay approach, contact me
off line and I'll scan it and send it to you. You can also make a
solid state affair with a triac instead of a relay and a op
amp/zener/etc circuit to activate the relay - I figured that since I
wanted a neutral anyway, I'd use the approach with the single relay. I
had built the two relay one first (and it worked also, but the one
relay one seems to work a little better). The second relay, if you
use it, should pull in around 70 to 80 V and drop out below 30 to 50 V
- you can use a DC relay with a diode and cap, or an AC relay.

On Sun, 8 Jan 2006 08:30:07 -0600, "Wayne S"
wrote:


"William B Noble (don't reply to this address)" wrote
in message ...
for what it's worth, I have good luck starting the 6 hp spindle motor
on my mill with a 600 uf starting cap, which is disconnected via a
potential relay once it's up to speed - the relay coil is wired from
the unenergized leg to neutral. it works very reliavbly. But if I
want to start the 2 HP motor that moves the table, I am better off
having the spindle running first.


I suspect I will go this route. Have to go and buy some start caps.
I've been collecting run caps over the years knowing I would eventually
build a phase converter, but don't have much for start caps.
You said the potential relay is wired from the unenergized leg to
neutral. Does 3 phase wiring have a neutral? I was expecting to use the
4th wire as ground. The 220 line is just 2 hots and gnd.
Wayne

Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com