Bridgeport Mill - Convert to 240v Single Phase

Hi All,

I've just become the owner of a Bridgeport Mill. Even better it was free (except £150 delivery).

On the motor plate it says 380/420, 3.2/2.1, 2700,1420, CONT INS E, SC, Frame 7, HP 2.0/1.0

I want to run it off 240v single with a VFD. I have already setup a lathe like this. I assume that this motor would not be compatible as it's not 240/415 - could someone with more knowledge than me please confirm this please.

I've attached a few pics.

Any help much appreciated.

Thanks

I'm currently (no pun intended) trying to set up a miller/engraver that is dual voltage, to run on a Yaskawa AC Drive J1000 from:

www.drivesdirect.co.uk/

A 'phone call or email to them may get you under way.

Brian

Might be an idea to contact Transwave who advertise on this site. One of their phase converters or similar might be a better option.

regards

The motor is definitely not dual voltage, although it is two speed. Presumably there's a switch in the control box somewhere that looks after the pole switching. Since the hp values are in a 2:1 ratio the pole switching is not accompanied by star to delta switching.

The motor appears to be a "pancake" style which is integrated into the drive so will be tricky to change to asingle phase or dual voltage motor.

Best bet is to find a way of generating some sort of approximation to 415V 3-phase. A good place to start would be to take Oldiron's advice.

Andrew

You will struggle to change the motor to vfd and if it was me I would go for a phase converter as other motors coolant pump, traverse motor and relays will also work no problem.

David

I would suggest you also talk with Direct Drives on 01623 720710 . They also have a useful web page . I have no connection with the company .

Trevor .

I've just found an old thread on 'rcgroups' discussing the same issue.

... Includes wise input from John Stevenson: **LINK**

https://www.rcgroups.com/forums/showthread.php?97992-2-speed-motor-and-inverter

MichaelG.

If you go the phase converter route look for a rotary converter. I tried to run my Bridgeport from a static converter and whilst it would run it stopped every few minutes throwing a trip out in it's electrics box. Transwave were more than helpful in trying to solve the issue but the static converter was not compatable, it has however run my lathe for years.

I think your best option, is to replace the current motor with a suitable 220V 3phase, and then make a new control panel that has a variable speed pot, and a forward reverse switch. It is essentially what I have done on my Myford lathe. I am going to make a similar setup for my new to me ZX45 mill. It is a clone of the RF45. Like the lathe, I will set up a micro switch that I can use when tapping holes. So when it gets to the desired depth, it stops. How quick depends on the deceleration settings on the VFD box. So if I ever wnat to put it back to it's standard configuration, I can just put the original motor back on, and reconnect all the wires etc.

Neil

Easy to say but difficult to do. Sure it's easy on something like a Myford, but on the Bridgeport the motor is non-standard in it's fittings and drive arrangement. No doubt it could be done, but you'd end up rebuilding the head.

Andrew

I have a Bridgeport and have converted it to to a VFD driven 220v 3 phase motor - BUT... it is not a simple job.

You have what is called a 'pancake' motor and these CANNOT be converted to 220v. Your quickest way of getting it working from a domestic supply is to use a rotary converter (Transwave) but these are not cheap. I did use a static converter for a couple of years and it worked, but it was fussy about the higher speed if selected.

To fit a conventional flange 220v motor in place of the 'pancake' you need a simple, thick steel adapter plate. There is no head rebuilding, just an 8mm plate that slides in place of the 'pancake' flange and holds the motor in the middle.

The problem then is that no readily available motors have long enough shafts to hold the pulley in the right place. I was fortunate in getting help from John Stevenson and he modified a new motor. I have heard of others who fitted extension stubs, but then suffered vibration. Personally, I think an extension stub, locked onto the shaft, and then turned true by spinning the motor clamped to a lathe bed, would give an acceptable result.

Once you have lengthened a motor shaft, and made an adapter plate, you then need to do quite a bit of re-wiring in the cabinet. It is best to set that all to single phase so that the front switch box still operates the contactors and nicely switches on the VFD. If you have a Bridgeport table axis drive then that will still happily operate on its 110V single phase once you have re-tapped the transformer.

Norm

A little out of the ordinary but VFDs for 240 to 415V do exist. As might be expected they are more expensive than their low voltage relatives, but then you got the Bridgeport for free! This cheaper example is from Drives Direct - worth a call I think unless the asking prices are too much.

Like the chap in the photo: he's wearing a high-vis jacket and slippers. That's exactly what I want for xmas - carpet-slippers fitted with steel toe-caps!

This is what I did for my lathe. I am making another box with a bigger drive, 2.2kw for my FR45 clone. Not the same as a Bridgeport. But the concept is similar. Where the motor controls are not connected to the original switch or carbonate. Some place are bringing in motors with longer shafts, maybe that is an option for the Bridgeport.

I've seen recommendations for inverters like this one. I've been considering one of these - 240V single phase in, 380V 3-phase out - for my lathe. The inverter I currently use with that struggles with the load when I wind the speed up because of the way it does the 240V-380V conversion. Might do for the Bridgeport, as you could buy an over-specced version to easily handle the load at quite a good price. There are a number of reviews of the Ecogoo inverters available via a Google search.

Thanks for the replies.

I'm not too keen on a static converter - read lots about them not working well with milling machines so feels a bit hit and miss..?

Rotary phase converter seems very expensive and I would think I could get a 2nd hand 230V 3-Phase motor and make it fit and then add VFD considerably cheaper.

That chinese Ecogoo option sounds perfect though - almost too perfect. Is it too good to be true?

If you have a motor rewinder near you it might be worth finding out what it would cost to bring out the star point and convert it to delta. I've actually done it on a bench grinder, but it didn't matter if that dies. Replacing a Bridgeport motor would be a bit more expensive to put it mildly, so consult an expert.

I took my 3-phase Bridgeport 2-speed 380/440V pancake motor to a motor rewinder in Southampton. He rewound it for me, so it's now a 3-phase 2-speed 230V motor. It now runs just fine on an IMO Jaguar VXR inverter which is 230V single phase in, 230V 3-phase out. The rewinding cost me about £300 three years ago. I only power this motor with the inverter, not the rest of the (Denford) milling machine that the head is fitted to.

David

The company is C&C Rewinds Ltd, 7 Test Valley Business Centre, Test Lane, Southampton SO16 9JW. No connection, just a very satisfied customer.

David

If you got the machine for nothing,I would not bother arsing around changing motors ect. Talk to Transwave,buy a rotary converter and forget about messing about,that,s what I did,and never looked back Over time,the cost will be buttons and at least you will be up and running