power and phase converter question for soon to arrive mill

<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> Hi Folks, <p>This is my first post to this group. I just recently purchased a used
CNC milling machine that has a 4.3hp motor. It should be arriving at my home (Dallas TX area) in about 1.5 to 2 weeks.&nbsp; So I'm trying to get everything ready for its arrival.&nbsp; The first task is power. I was thinking of either building&nbsp; or buying a rotary phase converter panel, and also buying a used 10hp 3 phase 1700-1800 240V motor as the required idler motor. <p>I am currently renting the home I am living in, so I can only do minimal damage to the walls in terms of running cable, etc.&nbsp; There are two sources of 240 power near to the garage: one is the dryer outlet, and the other is the water heater. The water heater is actually closer to the garage and is therefore a better choice if possible. The seller told me that the machine's manual specifies a 30amp 3 phase 240V power source.&nbsp; Both the dryer and water heater are on their own 30amp (single phase) circuits. About how much power are a 4.3hp milling machine and appropriate phase converter likely to draw? If my math is correct a 4500watt water heater will draw 18.75 amps; the leftover 11.25 max amps does not seem likely to be enough in my guesstimation. So is the dryer outlet the only option?&nbsp; If I use the dryer outlet, I'll need @25 ft of wire. What gauge wire should I purchase? <p>I read that you should get a phase converter that is almost twice as big (in terms of HP) as the motor in a CNC mill - hence my search for the 10HP motor.&nbsp; Do you all know of a good place to get a used 10hp motor (or the whole converter for that matter)&nbsp; in DFW?&nbsp; And can anyone paste a link to some good phase converter plans for this machine? I.E. some plans that are not too technically advanced in the required electrical knowledge, but still will yield a great converter at a good price. <p>Thanks a whole lot! <p>Mario</html>
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
On Wed, 10 Nov 2004 16:25:04 -0600, Mario

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Also check out a thread at PracticalMachinist:
http://www.practicalmachinist.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t0661
which has Fitch's RPC design and a bunch of tuning procedure description.
"Don Foreman" wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Even if you took the circuit over completely it is not sufficient if the machine specs 30A 3ph 240V. You will need something along the lines of a 60A 1ph 240V circuit and a fairly hefty phase converter to power this machine. You might be able to get the machine running for "dry" testing from your 30A circuit, but as soon as you tried to cut anything much tougher than cold butter you'd trip the breaker.
CNC make the power supply that much more critical with the computers and servos. On a manual machine if your power dips a bit when starting the motor it's usually not a big deal, but with CNC if it dips the computer crashes and the servos might do strange things.
In order to get this machine operational you will need to run a new circuit from the main panel.
Pete C.
Mario wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

FWIW, I've run my bridgy with a 5 hp phase converter on a 30 amp 220 VAC circuit for years. Also connected is a drill press, EDM, tool and cutter grinder, and surface grinder. I never have run more than two at a time.
There's also an EXCELLENT!!!!!!!! ARTICLE by our own Bob Swinney in an old issue of HSM magazine on how to build a phase converter. Even for the elctrically challanged <me>, its not a tuff job.
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.