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

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

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.

========================== 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

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

the sales brochure and for the whole skippy or convert to 220 1 phase see go with a treadmill motor

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).

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

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

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 Laws>My son has just purchased an old belt drive Bridgeport Mill with 575V 3

...

...

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

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

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

He *said* CDN.

That's what, $150 USD?

Here's my DC motor conversion:

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:

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

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:

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

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

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

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

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

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