# Electrical box mounted on Bridgeport



## S5rx7 (Mar 23, 2022)

This electircal box was mounted to the back side of my Bridgeport. You can faintly see it sticking out the back. It was wired to the switch. It appears to be a forward/reverse box? If so this would mean you can run the spindle in both direction in high gear? Maybe I'm way off here hoping someone would have some insight.


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## BGHansen (Mar 23, 2022)

I can't tell from your pictures but in normal use the BP can go in both directions in both open spindle and back gear.  My BP has a HIGH/LOW RANGE power switch on the LH side of the head.  Normally this is left in the OFF center position.  Flip it up to HIGH RANGE with the head in open spindle (high gear) and the spindle turns clockwise.  Flip it to LOW RANGE with the head in open spindle and it turns CCW.  It's bass-ackwards when in back gear (low gear).  Flip to LOW RANGE while in back gear to turn CW, HIGH RANGE to go CCW.  

In summary, match the RANGE to your spindle gearing for CW, mismatch for CCW.  I use the LOW RANGE all of the time for power tapping.  Turn on the BP (in LOW RANGE), advance the quill until the tap engages, flip the power off to stop the mill, and flip the power back on to HIGH RANGE to retract the tap.

By the way, there are a couple of unique things on my BP.  The previous owner made a bell crank for flipping the power switch.  The knob is mounted by the kick-out mechanism.  Lots more convenient than the high-mounted switch.  The toggle switch mounted just above the boring feed rate knob is the ON/OFF switch for a spindle light.  

Also, my BP is powered by a static phase converter.  The previous owner mounted the converter above the Anilam controller and used a DPDT lamp switch to power up/down the converter.  In use, the mill's normal power switch is left in the HIGH/LOW RANGE and the mill is powered on/off with the toggle switch.  As cheesy as it looks, it works well for me.  I don't understand the electrical side of it, but if I leave the phase converter on and use the normal switch for ON/OFF, the phase converter buzzes with the normal power switch off.  I suspect the relay in the static converter is cycling at 60 Hz.  I've read others having the same condition with their converters.  As usual, more than you wanted to know!

Bruce


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## ErichKeane (Mar 23, 2022)

It appears to be a contactor box to me (to be used with a magnetic switch), I don't see anything about 'reverse'.  I would imagine there is a drum switch somewhere (either between this and the motor, or between the source and this box) that changes direction.


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## jbobb1 (Mar 23, 2022)

Looks like a FOR/REV contactor set up. Some Bridgeport mills, and clones like mine have a drum switch. The reversing is done mechanically within the switch verses having individual for/rev contactors (like in your pic's) that are energized electrically by a switch, which I assume is mounted on the left side of the machine.


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## ErichKeane (Mar 23, 2022)

jbobb1 said:


> Looks like a FOR/REV contactor set up. Some Bridgeport mills, and clones like mine have a drum switch. The reversing is done mechanically within the switch verses having individual for/rev contactors (like in your pic's) that are energized electrically by a switch, which I assume is mounted on the left side of the machine.


Ah, TIL!  Listen to him instead   I saw the two contactors and it looked like my shaper so I figured it was like that!).


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## sdelivery (Mar 23, 2022)

I prefer the fwd/rev contactor to a drum switch.
The thermal overloads are a plus


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## MikeInOr (Mar 23, 2022)

That forward / reverse contactor setup will last for ever.  Eventually a drum switch will get dirty, start arcing and pretty much burn itself out.


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## JimDawson (Mar 24, 2022)

Yup, reversing contactor set up.  Never seen that on a BP before.


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## S5rx7 (Mar 24, 2022)

It actually has a drum switch


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## JimDawson (Mar 24, 2022)

The reversing contactor was most likely installed to move the high motor voltage away from the drum switch to meet a regulatory requirement.  Normally 240V or even 480V is wired directly to the drum switch, and that is not the safest way to do it.  Much safer for the operator with the reversing contactors and the drum switch switching 120V.

Today, running the motor with a VFD and having 24VDC controls would be my first choice.


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## S5rx7 (Mar 24, 2022)

JimDawson said:


> The reversing contactor was most likely installed to move the high motor voltage away from the drum switch to meet a regulatory requirement.  Normally 240V or even 480V is wired directly to the drum switch, and that is not the safest way to do it.  Much safer for the operator with the reversing contactors and the drum switch switching 120V.
> 
> Today, running the motor with a VFD and having 24VDC controls would be my first choice.


I have a phase converter. I have multiple machines I need to wire up and configure. Doing it with the least amount of obsticales would be ideal. Once I get to that hurdle I'll have to come up with a plan. Basically I really don't need the box? I can wire 240v/460v straight to switch/motor?


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## JimDawson (Mar 24, 2022)

S5rx7 said:


> I have a phase converter. I have multiple machines I need to wire up and configure. Doing it with the least amount of obsticales would be ideal. Once I get to that hurdle I'll have to come up with a plan. Basically I really don't need the box? I can wire 240v/460v straight to switch/motor?



Since you already have the reversing contactor, rather than wiring the switch directly, I would use the reversing contactor, much safer.


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## ErichKeane (Mar 24, 2022)

JimDawson said:


> Since you already have the reversing contactor, rather than wiring the switch directly, I would use the reversing contactor, much safer.


Depends on the converter I would think? Is it a VFD?


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## sdelivery (Mar 25, 2022)

You can use a vfd with the fwd/rev contactor or a drum switch with one very important detail Never Ever switch the load while the vfd is outputting to the load.
I have used the inverters on control source to a drum switch but that is controlling the vfd.


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## S5rx7 (Mar 26, 2022)

JimDawson said:


> Since you already have the reversing contactor, rather than wiring the switch directly, I would use the reversing contactor, much safer.


I'm trying to wrap my head around how exactly it works. I need to stare sit it some more.


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## S5rx7 (Mar 26, 2022)

This is not a VFD. I do not own VFD's.


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## IamNotImportant (Mar 27, 2022)

S5rx7 said:


> It actually has a drum switch


i like the base on that machine


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