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Hello Everyone,

A while back I purchased a used 3 Phase Bridgeport style Mill. The control Panel it came with was pretty poor, but worked for my uses so I didn't give it a second thought until recently I started having some issues.

The current set up I have is 3 phase power comes into the box to an old Allen-Bradley Relay that is triggered by a 120V AC switch. The other legs go directly to the mill motor. The Relay is triggered by a normal wall switch mounted to the panel that has a normal Edison plug that goes into an AC outlet to give that side of the relay/switch power. When I flip the switch up the relay activates giving power to the mill, when the switch is off the relay cuts the power to the mill. Of course this is not ideal because I don't have a reverse, there is no inline fuse in the panel, or E stop to cut the power if the relay sticks. Did i mention relay sticking? That is the issue i'm having now, and I have to cut the power at the phase converted (not in the control panel but mounted to the wall of my basement to turn the mill off. Needless to stay due to dangers with the machine not being able to safely stop at the work station I stopped using it.

I would like to purchase/build a new control panel that, doesn't need to be plunged into the wall of a separate outlet, but can operate off of the incoming 3 phase power on its on, E-stop switch, 15 amp time delay fuses on each leg, forward and reverse relays, and on/off buttons, and this might be getting greedy, but perhaps a current meter to see what my motor is drawing?

Anyway i have done some searching without much luck finding an off the shelf unit, or finding a guide to building one. Can anyone point me in the right direction of how to proceed? I have some wiring experience and don't think I'll have an issue putting a system together, it is more of a matter of finding a guide for sourcing the right components and where to purchase them from.

Any advice would be greatly appreciated.
 

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Hello Everyone,

A while back I purchased a used 3 Phase Bridgeport style Mill. The control Panel it came with was pretty poor, but worked for my uses so I didn't give it a second thought until recently I started having some issues.

The current set up I have is 3 phase power comes into the box to an old Allen-Bradley Relay that is triggered by a 120V AC switch. The other legs go directly to the mill motor. The Relay is triggered by a normal wall switch mounted to the panel that has a normal Edison plug that goes into an AC outlet to give that side of the relay/switch power. When I flip the switch up the relay activates giving power to the mill, when the switch is off the relay cuts the power to the mill. Of course this is not ideal because I don't have a reverse, there is no inline fuse in the panel, or E stop to cut the power if the relay sticks. Did i mention relay sticking? That is the issue i'm having now, and I have to cut the power at the phase converted (not in the control panel but mounted to the wall of my basement to turn the mill off. Needless to stay due to dangers with the machine not being able to safely stop at the work station I stopped using it.

I would like to purchase/build a new control panel that, doesn't need to be plunged into the wall of a separate outlet, but can operate off of the incoming 3 phase power on its on, E-stop switch, 15 amp time delay fuses on each leg, forward and reverse relays, and on/off buttons, and this might be getting greedy, but perhaps a current meter to see what my motor is drawing?

Anyway i have done some searching without much luck finding an off the shelf unit, or finding a guide to building one. Can anyone point me in the right direction of how to proceed? I have some wiring experience and don't think I'll have an issue putting a system together, it is more of a matter of finding a guide for sourcing the right components and where to purchase them from.

Any advice would be greatly appreciated.
It's not clear what your control panel does except actuate the relay that turns the motor supply on and off. Is this a delta or wye configuration? With a delta (most common), you can get 220V to power your control panel by using any 2 of the delta poles. With a wye, you can get 220V to power your panel by connecting to the neutral and any one of the 3 poles. In either case you'd need a small transformer.

That being said, you should not need to use 120V control components. Everything is available to work off 220V 3 phase and that is how most things are done today. See here for an example. You'll notice that the only thing the neutral is used for is to power the 120v indicator lamp.

Al
 

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what Is your 3 phase voltage? A control voltage transformer can be added to get you the correct voltage. Have you considered using a variable frequency drive? Can be programmed for soft start, braking, and will also simplify the reversing....all of this is assuming you have a need for being able to adjust your speed too? I have never physically been around a mill. The Estop can be ran through the drive too. In any case I would recommend a fused safety switch mounted on/beside the control panel to ensure some one can immediately switch the incoming power off.
 

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I would upgrade to a VFD (Variable Frequency Drive), that will give you on/off, speed, direction, and even braking and e-stop if you want it.

Some pics of your setup will really help us too...
 

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How you going to power tap without reverse!
You must have a variable speed belt drive. The old step pulley systems needed reverse when you were in back gear.
Simplest thing to do would be just to install the normally equipped, manual three phase reversing drum switch.
If you really wanted to stay with a "control" and no reverse, you would just install a properly sized three phase motor starter that used an operating coil designed to accept your line voltage. Then no need to transform down to 120 or 12 or whatever.

If you spent more you could also get a reversing three phase starter that operated at line voltage. You would have a separate switch to select direction.

Of course you would need to buy or make an enclosure to mount these in, or buy as a package "motor starter in enclosure".

Manual drum switch would be a whole lot cheaper unless you have access to a bunch of surplus electrical apparatus.
 

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What Kenny said.

Into your "box" you run 10-2 220VAC. Feed the VFD 220 1ph and you can take (steal some 110) one leg of the 220 if you have to feed the machine lamp or DRO but I don't know why you would want to do that. If you are making 3ph from 110VAC I'd have to ask why. 220 is much more efficient.

In my box I have the VFD and a relay with circuit breaker that feeds my 3ph power feed. My 110VAC needs are for the machine lamp and DRO that are plugged directly into the wall outlet.

When my machine is not being used I shut the breaker off feeding the VFD.

Edit: I should have added I'm using the drum switch from Bridgeport. No way would I run that machine directly off the VFD. Being a prior machinist I'd hurt myself doing that. One thing I failed to mention is the amperage draw on the machine even when dropping it into reverse like when power tapping is nothing. You could power the machine with lamp cord.
 

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Discussion Starter #7
What Kenny said.

Into your "box" you run 10-2 220VAC. Feed the VFD 220 1ph and you can take (steal some 110) one leg of the 220 if you have to feed the machine lamp or DRO but I don't know why you would want to do that. If you are making 3ph from 110VAC I'd have to ask why. 220 is much more efficient.

In my box I have the VFD and a relay with circuit breaker that feeds my 3ph power feed. My 110VAC needs are for the machine lamp and DRO that are plugged directly into the wall outlet.

When my machine is not being used I shut the breaker off feeding the VFD.

Edit: I should have added I'm using the drum switch from Bridgeport. No way would I run that machine directly off the VFD. Being a prior machinist I'd hurt myself doing that. One thing I failed to mention is the amperage draw on the machine even when dropping it into reverse like when power tapping is nothing. You could power the machine with lamp cord.
I'm not making 3 phase from 110v. I might not have stated that clearly. I have 220 going to a static phase converter that makes the 3 phase. That then goes to an allen Bradley relay in the box and from the relay to the motor of the mill.

The 110v is needed to activate the relay and is on its own separate loop that i'm plugging into a normal 110v outlet for power. I'll try to upload some pictures tonight. I was out of town the last few weeks and didn't have any good photos to share.

I really don't have a need for the VFD as the machine has mechanical speed adjustment that works just fine for my purposes. Plus they are $$$ in my experience, so without a need for it justification is difficult.

Perhaps just a drum switch is all I need. I'm not quite sure why a relay was used in the first place, I don't think this is a motor starter tied to it. I'll post the photos and hopefully you call can help me decide.
 
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