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
Reply to
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
Reply to
Dave August
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.
Reply to
Pete C.
========================== 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
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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
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the sales brochure and for the whole skippy
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or convert to 220 1 phase see
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go with a treadmill motor
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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 Helvétius (written 1773-76; first published 1875; repr. in Selected Writings, ed. by Lester G. Crocker, 1966).
Reply to
F. George McDuffee
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
Reply to
Trevor Jones
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
Reply to
Ned Simmons
Hey Jimbo,
The cost of a rewind sounds high, but it is "special", so.maybe it is the going rate. Check with at least one other rewind shop though.
The transformer installation would be less, but it won't give you three phase.
Check on the cost of a new single phase 220 at someplace like Princess Auto too.
If it was me, I think I'd opt for a 3 phase 220, and build a rotary phase converter as the supply source.
Take care.
Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXXXXXXXXXXX
Reply to
Brian Lawson
...
...
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
Reply to
Karl Townsend
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
Reply to
Donnie Barnes
Friend of mine "bought" a single phase motor for an Asian BP clone. It was a direct drop-in. Actually, he traded his 3 phase motor for it, even up... Actually, I think the deal was that the dealer had a single phase clone he wanted to sell to a shop that had three phase. But, I don't think it would have been all that expensive had he bought it outright.
Jerry
Reply to
Jerry Foster
He *said* CDN.
That's what, $150 USD?
Reply to
Richard J Kinch
Here's my DC motor conversion:
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If nothing else, you can get the dimensioned drawing to make an adapter plate if you want to go the VFD route with a lower-voltage 3-phase motor:
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Reply to
Richard J Kinch
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
Reply to
Trevor Jones
There is a company in Roberts, Wisconsin that rebuilds Bridgeports. They don't resell J heads, so they have a pallet load of those heads laying around. I have no idea what voltages they might have. If you are interested, email me off-list and I can give you the name and phone number for the company.
Pete Stanaitis ------------------------
Jimbo wrote:
Reply to
spaco
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
Reply to
Gunner
Dude,
Looks just about like what I did.. 'cept my motor isn't a TEFC.. Mines an old spindle motor out of a computer tape drive.. air cooled, has a hose connection right above the burshs and vent holes at the far end, I even got the original blower from the tape drive.. it was used to create the vacume for the tape and the output cooled the motors.. LOL...
Also the guy I bought my BP from had replaced the old worn out factory motor with a Lesason and had already made the motor mount plate. All I had to do was drill the 4 holes for the NEMA pattern.
FWWI I got all the stuff for free :-)
--.- Dave
Reply to
Dave August
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
Reply to
Mark Rand
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
Reply to
Joseph Gwinn
On Thu, 14 Sep 2006 00:52:19 -0500, with neither quill nor qualm, Richard J Kinch quickly quoth:
In post-Shrub dollars, it's about $650. I used to get a damned nice rate for Lee Valley tools and such until the Bush JR years.
-- Nothing is a waste of time if you use the experience wisely. -- Rodin
Reply to
Larry Jaques
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
Reply to
Gunner

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