Guys with Bridgeports at Home

What are you using to go from 220 single phase to 230 3 phase? Static Phase Converter or VFD?

rotary

VFD but it must connect directly to the motor, no contacters.

I wired the VFD to the motor and removed all the wiring, contacters, transformers etc. from the big wiring box and rewired the power feed, coolant pump (new 110V) and lights to 110V.

Mine has the Varispeed head so I use it to control spindle speed and set the VFD to 60Hz.

Hands down - VFD. You want the variable speed and the braking capability of the VFD.

Foe mine, I replaced the original 1 hp motor with a 3 hp aluminum frame motor. I think I paid around $250 for the motor. I went with the 3 hp to make up for lost torque because I went with a single pulley - this way no more changing belt position to get a wide range of speed. Leave it in a high speed position and use the VFD to lower the speed.

You have a few options for braking with a VFD. The best solution is to use a dynamic braking resistor. I use DC injection - not as good but is decent and easier to implement.

Don't plan on listening to AM radio when the VFD is on................

That's not really true. If the drive is closely rated to the motor size, then the drive will trip on over-current if you close the contactor when the drive is on. If the drive is oversized, then closing the contactor while the drive is on won't hurt a thing. Neither the motor or drive would care, but in a single motor application like this it does not make sense to do this.

For example, my surface grinder spindle is a 1 hp motor. The coolant pump is 1/6 hp. I run both off of a single 1 hp drive (I don't exceed the drive rated amps). I slam the coolant pump on/off at will with a contactor when the drive is running the spindle. Works absolutely fine.

The trick is the drive must be able to provide the inrush current and the drive needs to be set up in volts/hertz mode. For a mill you prefer sensorless vector mode because you don't lose torque at low speeds like you do in volts/hertz mode. No issues if you don't run in volts/hertz mode at low speeds.

My mill is volts/hertz (so old it don't have sensorless vector mode) and I can stall the motor at very low speeds.

Changed the motor to single phase.

I built a rotary phase converter for under $20 using cast off parts that I scrounged: a 5 horse 3 phase motor for the converter, a 1/2 horse 110 motor to start the converter motor spinning, and then bought 2 pulleys and a belt to connect them.

I’ve used the phase-a-matic converters in the past. I would get 2 to 3 years out of them. Fixed one a few times. Finally went with a rotary phase converter. Machines run much smoother, and reversing on demand works perfectly. No comparison between the two on performance.

I have a 2hp 230 3 phase motor, 60hz, and a vfd rated for 2hp. I've set the parameters in the vfd for the hp, voltage and hertz. I go to click the fwd/rev switch to turn the motor on and the vfd overload faults. I have the variable speed on the vfd set to 60hz. Ive tried lower settings, still get the overload fault. Motor is freshly rebuilt, spins freely.

steff,

just swap the motor. on the older bridgeports you had either a bunch of pulleys and needed to swap belts or the variable pulley to change the spindle speed. either used a single phase motor run at 60hz. if you run a regular 3 phase motor with a vfd, you will lose torque at low rpms or at higher rpms if you over run it. if you run it at 60hz you don't need a vfd. buy a single phase motor at the correct rpm and be done with it. surpluscenter.com is usually where I get my motors. that or ebay.

Jerry, this mill is not terribly old. It has the adjustable speed knob on it. There is one big drive belt with a spring loaded pulley on the motor. I just had the motor rebuilt from 480 3 phase to 230 3 phase, due to the extended shaft on the motor and bearing support at end of motor shaft. Figured it would be less hassle than finding an exact replacement motor with the exact shaft.

I use a static converter on my Bridgeport. No issues.

I use a rotary on my CNC.

A little bit of rewiring and Steff will be fine!

A little birdie told me.............

Thanx Mark! Email sent.

I want one so BAD, hate to hijack but,
I have a 50 hp Roto-Phase converter for my other 3 ph machines, so am I good to go? You guys are talking way over my head.
PS. I want one I can put an engine block in.

We have 12 of bridgeport and other brand Mills at work. I can use any of them when I need to but I still want one for at home someday along with a nice lathe.

A Lathe is on my list and then I will be self sufficient.

What kind of rewiring are we talking about here. Id be interested to know?

Your good to go for anything with a motor size up to 25 HP

you can't rewire 3 phase to single phase. if you've already got the motor rewound for 240 vs 480, the either a static or rotary phase converter will work. heck even a vfd set at 60hz will work as well, just way overkill for what you're trying to do.

my vote would be a rotary phase converter and get one large enough to support all your machines and a compressor.

He got it running temporarily. He was turning it on through the original switch which is on the motor leads. Since he has a 2 hp drive with a 2 hp motor (nothing wrong with that) you can't switch the motor onto the drive.

He needs to wire the motor directly to the drive and then either put a small toggle switch in to run the drive or rewire the existing switch into the drive controls to stop/start and fwd/rev.

That's what I have too John. Makes life easy.

- EM

Yep, my rewind is 3 phase. The VFD I got was $112 on Ebay. Overkill but cheap.

https://m.youtube.com/watch?v=cFPId8fgZV0

What I neglected to tell Steff is that he probably would have been just fine not rewinding the motor.

My original Bridgeport from 1966 came with a 1 hp motor. Later ones had a 2 hp (I believe).

Since his motor was 480 volt at 2 hp, he could of run it up to 240 volts (linear voltage ramp from 0 to 240 volts and varying the frequency from 0 to 30 hertz) in constant torque mode up to 50% speed and then constant hp mode from 50 to 100% speed (fixed 240 volts but vary the frequency from 31 to 60 hertz).

What does that mean? It means that he would have had rated hp up to 50% speed, but from 50% to 100% speed he would have been limited to 1 hp output. I don't think he ever would have had a problem being limited to 1 hp at the higher speeds.

But too late now!

What are you guys doing to contain the coolant when milling?

My mill is not a bridgeport. But an Enco chinese 2 hp 3 phase. I have an Allen-Bradley converter. Mill is manual speed change. Converter changes it to single phase without any hp loss and gives me variable speed. Plus spindle direction change at the push of a button. I don't know the cost of unit it was given to me as a retirement gift about 15 years ago. It has worked flawlessly. All the info I have is: Bulletin 160 SSC tm variable speed controller (series B) .037-2.2 kw (0.5-3hp)
Hope you all can find the unit. Works great!!