Advise Needed On Converting Bridgeport Mill From 575V to 220v Single Phase

My son has just purchased an old belt drive Bridgeport Mill with 575V 3 phase motor. We only have 220 single phase in our hobby shop and I have
been told by a local rewinding shop that they can rewire the motor to run on 220V single phase for probably no more than $700.00 CDN. Another option would be to remove the original motor, sell it and adapt a new 220V single phase 1HP or 1 1/2HP reversing vertical mount motor to the machine.
I have been told by a local electrician that my only other option would be to buy a 220V to 557V phase converter then a step up transformer but I'm pretty sure that would cost a lot more than we have to spend.
My questions are, has anyone on this newsgroup converted a belt driven Bridgeport to 220V single phase? If so I would appreciate all the info I can get before we take delivery of this machine. I am also curious to know if the 3 phase motor on the machine is in much demand and what a fair price would be if I decide to sell it.
You can respond to me on this newsgroup or E-mail me at jimbo snipped-for-privacy@yahoo.ca
Thanks in advance
Jimbo
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Jimbo,
The best thing to do is go with a VFD that converts 220V Single pahse to Variable Frequency 3Phase.. I'm no expert of VFD (I actually stuck a DC motor on my BP but thats another story) so I'm not sure that you can get a VFD that'll put out 575V (man that's sure a squirly voltage) but I'm pretty sure you could get a VFD and a used 3 pahse 220/440 motor for WAY under the $700 CDN you got quotted... IIRC the VFDs are about $350 USD and a quick check on eBay show 3/4 to 1.5 HP 3phase 220V motors in the $100 USD and under in both 1725 and 3450 RPM...
No matter what you do swapping motors isn't that hard so.. All i had to do was make a bushing for the pully...
And I'm sure some guys will answer who know more than I do... --.- Dave

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Jimbo wrote:

In the US if faced with a 480V only motor on a Bridgeport (more common is 220/440V reconnectable) the easiest solution would be to use a 480V VFD rated for single phase input and scrounge a suitable single phase transformer to step up the voltage supplied to the VFD. You don't want to put a transformer on the output of a VFD. This setup would probably cost about $400 US or so at most depending on scroungability, could be a lot less. The VFD gives you soft start and variable speed as well.
The Bridgeport motor is a special mount so if you wanted to replace the motor you would have to either find a used one, or fabricate an adapter plate for a standard motor mount.
Pete C.
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wrote:

=========================Price seems high to me [but then I'm a cheap screw...]
Price on VFD drives has fallen and your best bet may be to get a rebuilt 220 v 3 phase motor and VFD. I was able to get one of their units with single phase 120 input than generates 220 3 phase out with vfd. Eliminated running another line to the shop. I bought from http://www.driveswarehouse.com good service and prices. I'm sure you have a good Canadian dealer to eliminate the customs problems.
Their L200 series appears to have models that have 220/1i n with 460/3 out in addition to 220/1 in and 220/3 out
see http://www.hitachi.us/supportingdocs/forbus/inverters/Support/L200_SM-E242R.pdf for the sales brochure and for the whole skippy http://www.hitachi.us/supportingdocs/forbus/inverters/Support/L200_QRG_NB6601XA.pdf http://www.hitachi.us/supportingdocs/forbus/inverters/Support/L200_Instruction_NB660XA.pdf
or convert to 220 1 phase see http://cgi.ebay.com/BRIDGEPORT-2hp-SINGLE-PHASE-CONVERSION-MOTOR_W0QQitemZ290026922380QQihZ019QQcategoryZ26226QQssPageNameZWDVWQQrdZ1QQcmdZViewItem also http://cgi.ebay.com/Bridgeport-mill-1-h-p-J-head-spindle-motor-rewound_W0QQitemZ160027133759QQihZ006QQcategoryZ41942QQssPageNameZWD1VQQrdZ1QQcmdZViewItem http://cgi.ebay.com/Bridgeport-2J-Head-Spindle-Drive-Motor-2HP-1-NR_W0QQitemZ290025280292QQihZ019QQcategoryZ41942QQssPageNameZWDVWQQrdZ1QQcmdZViewItem or go with a treadmill motor http://www.truetex.com/dcdrv.htm
FWIF -- review the achieves for the "spot the Babin" threads (Look out for all caps and "funky" spelling.)
FWIW -- I had a belt break on a J head and was too lazy to take the head apart to put a new belt in. Used one of the "emergency" cut to length fan belts the auto stores sell. Worked fine for two years and may still be running. Some people report that the "link-belt" works *BETTER* than the standard v-belt, and these can also be installed w/o head disassembly.
Unka George (George McDuffee) ..................................................................... The arbitrary rule of a just and enlightened prince is always bad. His virtues are the most dangerous and the surest form of seduction: they lull a people imperceptibly into the habit of loving, respecting, and serving his successor, whoever that successor may be, no matter how wicked or stupid.
Denis Diderot (1713-84), French philosopher. Refutation of Helvιtius (written 1773-76; first published 1875; repr. in Selected Writings, ed. by Lester G. Crocker, 1966).
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Jimbo wrote:

Good frikken greif! $700!!!
Shop for a brand new motor, and don't shop at the same place that gave you that quote, they are trying to rape you, IMO
Buy a 220v three phase motor, and a variable frequency drive and have variable speed at the touch of a button.
Cheers Trevor Jones
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Trevor Jones writes:

He *said* CDN.
That's what, $150 USD?
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Richard J Kinch wrote:

Nope! $630 US.
Doesn't matter, though, as we get paid in Cdn currency and have to work with the stuff in the local economy. $700 is $700. 70 hours of work at $14-$15 per hour after taxes get raked off.
$630 USD for a rewind on a replaceable motor is still a ripoff.
Cheers Trevor Jones
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On Thu, 14 Sep 2006 00:52:19 -0500, Richard J Kinch

Im installing a couple 1hp vfds, on a pair of Hardinge HSL speed lathes. The brake solenoids burned out..and Hardinge wont sell just the solinoid, must buy the entire motor for $650. Two 1hp GS1 vfds are $125 from Automation Direct (each), a pair of cans and my labor come to about that $650 price for one.
All they need to do is stop quickly.
Gunner
"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."
"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion). -Buddy Jordan 2001
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I'd have thought that the brake solenoids would be a very simple rewind job. But maybe so simple that it just isn't worth it for a rewinder (minimum order charge).
Mark Rand RTFM
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Rewinding a solenoid on a lathe ought not to be too hard. If they run at 220 or 575 volts, there will need to be lots of interlayer insulation strips. Basically, this is high-grade brown paper. For $650, it should be worthwhile.
But I wonder what burned the solenoids out in the first case.
Joe Gwinn

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wrote:

These are your basic big assed lever acting solenoids. But they are hard to find, and the customer wants em right now. Shrug..so I install em and get a check. Badly needed one too...sigh.

No idea..but Ive seen maybe a dozen in similar meltdown condition over the last 5 yrs.

"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3
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<snip>
Aren't the Hardinge brake solenoids AC and pull the brake off? If so, then dirt or similar stopping the solenoid from pulling the brake arm all the way will cause a higher current than normal. The inductance of the solenoid goes up once the air gap is closed, lessening the current in the coil.
Just a thought...
Mark Rand RTFM
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wrote:

Correct. And there is a lever allowing the solenoid to be manually pulled out of braking position and locked there. So one would assume that in that position..the heat builds up as long as the lathe is powered up and over the years....
This brake unit is intergral to the motor, in an elongated sheet metal end cap, not like the brakes mounted to the motor plates on regular Hardinge machines and snubbing against the motor drive pulley.
Gunner
"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3
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The options I'd consider, from least to most expensive, though the scenarios could easily switch places depending on what sort of deals you can find on used stuff.
-Keep the 575 volt motor, get a 240 to 480 volt step-up transformer and 480 volt variable frequency drive (VFD), and tell the VFD it's driving a 50 Hz motor. You'll lose 1/6 of your horsepower, but otherwise everything will be fine.
-Keep the 575 volt motor, get a 240 to 600 volt step-up transformer and 600 volt VFD to drive the motor. 600 volt VFDs are relatively expensive and not as common as 240 and 480 volt models.
-Replace the motor with a used 240 volt 3-phase Bridgeport motor and drive it with a 240 volt VFD. This is the cleanest solution.
I wouldn't even consider a single phase motor. A VFD will not only make three phase from single phase, it'll also give you continuously variable speed; a big bonus, especially on a step-pulley mill.
If what I wrote above is gibberish to you, ask more questions and I or someone else will try to explain.
Ned Simmons
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...

...
As always, Ned has real good advice.
I'll add one low cost solution to consider. Go to a local scrap yard that has a pile of used three phase motors. These are very common and inexpensive, at least in my area. Find one that is close and fabricate a special mounting for it. Shouldn't be that big a deal. I'm sure any motor you find will be longer (taller) than the original so make sure you have the space in your shop for ceiling height.
Then go with either a home made phase converter (real low cost) or the VFD(much nicer)
Karl
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On Wed, 13 Sep, Karl Townsend wrote:

Just make sure you get a 220V one to make life easier (I'm sure you meant that, but thought I'd add it just in case).
If you do go the step-up route with your current motor, I have some 460V VFDs that I'd sell pretty cheap.
--Donnie
--
Donnie Barnes http://www.donniebarnes.com 879. V.

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Ned, I understand about the 1/6 power loss due to running the 575V motor off 480V , but why tell the VFD it's a 50 cps. motor? I thought Canada was the same as the US, 60 cps. line voltage?
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I personally think it's a fool's errand. Those motors - in that form- factor, are available new and rebuilt in 230V ratings. They're not all that costly.
Lloyd
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On Sun, 22 Mar 2015 16:32:30 -0700 (PDT), Garrett Fulton

That thread's old enough that I don't remember writing that, but I can explain it. Simple open loop VFDs are often called volts/Hz drives because they adjust their output to maintain the voltage to frequency ratio constant as the frequency changes, which in turn keeps the motor current more or less constant. So if you tell the drive the motor's nameplate says 480V / 50Hz, the drive will output 480V at 50Hz, instead of the default (in the US) 480V at 60Hz.
480/50 = 575/60
--
Ned Simmons

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On Sunday, March 22, 2015 at 9:07:34 PM UTC-4, Ned Simmons wrote:

Okay. I understand. Thanks for the time.
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