Bridgeport Mk1 2HP Milling Machine re-commissioning

[Slooby]

Following on from the brief mention in my own introduction the other day I thought I would share, and seek advice, on the re-commissioning of my mill.

A purchase made from ebay between Covid lock-downs which has sat in my workshop ever since. Now, with a bit of time being freed up I looking to get it running.

Pics of it from the eBay auction:

And a couple of bits of tooling that came with it:

The fun and games of getting it home:

Where it sat outside my metalshop (we kinda have a woodshop here too), under the tractor shed with my Harrison Lathe (which will get its own thread), for a month or so while I cleared out all the stuff that had been dumped in it so that I could a) recalaim my space to b) get on with my own stuff:

Before getting placed, all be it temporarily for now, roughly where I aim to set it up:

With things taking place on the Harrison I've started to think about what will be required on the Bridgeport, and yesterday took a look inside the electrical enclosure...

Ahh...hmmm...what on earth is going on in there!?! From the fact that it has powered drives on each bed axis, and a factory option DRO fitted, I'm guessing the MGE Isolating Transformer at the top is providing their 110V supply, but there are dead legs everywhere and that black box floating around at the bottom :/ Hum this might not be so straight forward. Anyone recognise anything????

Supply wise I don't have 3 phase and was thinking of going down a Digital Phase Converter route to supply 415V to it and drive everything through the cabinet as one...now having looked in there...Help!

 

[Spectric]

I don't have 3 phase and was thinking of going down a Digital Phase Converter route

That is the most logical route to get a supply but that wiring is in a bit of a mess, If I were you I would try to draw a layout of the interconnections to work out what is what and then go from there.

 

[Sideways]

We need photos with more resolution and more angles as there are wires obscuring important details. Esp the voltage label on the transformer tap hiding behind the red wire.

It's old enough !
Brown things top right are a pair of 3 phase contactors each with a thermal overload relay on the output. So they will be for driving 3 phase induction motors. Not enough detail in the photo for us to read what current the overloads are set to.
Single brown thing in the middle is another contactor, this time without the thermal overload

Just checking BTW, it only has 2 motors, yes ?
Spindle motor and power feed on one axis, the traverse.

Rise and fall is manual.
Table forward and back is manual.

You have a light which may be 240, 110 or low voltage.

You have a coolant pump which might be 110 or 250V. That is controlled from the front panel so may be the 3rd contactor. Pumps are quite low power and in principle, unless they sieze or get blocked, the load on them is constant so that might well be connected to the contactor in the middle without the thermal overload.

The black box down below - take more photos, find a label, more detail of the connection area.

Same for the gizmos with the three round whatevers

In industrial control, it is common for 12v or more often 24v to be used to go through switches and operate the coils of contactors switching the 415v. It doesn't need to be DC for this. Low voltage AC is fine.
This is a safety thing.
It's not always done that way but if you are aware of it, it's easier to spot.

 

[porker]

I have one similar but a little simpler than yours as it didn't have any electronics as such and with the simpler J head. I put in two vfds from Direct Drives to power the existing 3 phase motors. Had to change the main spindle motor to delta and if I remember, the X drive was already 230v.

I think with the existing electronics on this machine I would agree a digital phase converter feeding the whole machine would be a better approach. Looks like a nice machine

 

[Spectric]

Same for the gizmos with the three round whatevers

I think they are fuses, I do recall seeing something similar in a very old bakelite control box many moons ago.

 

[ChaiLatte]

At vintagemachinery.org, they have extensive archives of many Bridgeport manuals, so they are worth looking at to see factory wiring diagrams.

 

[Spectric]

This has some resemblence

http://vintagemachinery.org/pubs/2099/16770.pdf

and https://www.model-engineer.co.uk/wp-content/uploads/sites/4/images/member_albums/93892/870748.jpg

 

[HOJ]

Defo fuses, used to see them all the time in big control panels, interesting that we have cable ties on the loom, and a piece of DIN rail on the contractors, what age are we on the the original machine.

 

[Slooby]

Thanks all, adding some more detail capturesfrom the full resolution images and new ones now:

It it helps explain what the MGE Isolating Transformer is doing; on the Primary side the wires are connected to '0' and '420', and on the Secondary '0' and '110'. Someone has suggested that the Primary has two of the phases connected to it and then the Secondary is outputing 110V Single Phase.

The Black Box is not labled, however it maybe the control board for the table drives

 

[Slooby]

Defo fuses, used to see them all the time in big control panels, interesting that we have cable ties on the loom, and a piece of DIN rail on the contractors, what age are we on the the original machine.

I'm not entirely sure myself, however looking at a brochure from 1980 the Heidenhein DRO fitted on the machine was shown as a factory option, so my guess is it's an 80's build. Anyway of finding out from the serial number?

 

[Slooby]

This does look incredibly similar and from a 1984 machine:

https://www.model-engineer.co.uk/forums/topic/bridgeport-circuit-questions/

 

[Spectric]

explain what the MGE Isolating Transformer is doing; on the Primary side the wires are connected to '0' and '420', and on the Secondary '0' and '110'.

Because the supply is only three phase with no neutral then you need a transformer to obtain the lower control voltage from the 400 volt three phase. It is nice to see through hole components on that PCB rather than the modern surface mount which are not so easy to work on.

 

[Spectric]

More info

https://hardinge.com/wp-content/uploads/KneeMill-Parts-Older.pdf

 

[Slooby]

Because the supply is only three phase with no neutral then you need a transformer to obtain the lower control voltage from the 400 volt three phase. It is nice to see through hole components on that PCB rather than the modern surface mount which are not so easy to work on.

Ahhah, so everything powered off that transformer is running at 110V single phase, and potentially could be powered separately via a conventional single phase supply with neutral hooked up to '0' and live to '220' on the Primary side. That could make things easier and mean that I could use a relatively inexpensive Digital Phase Converter without the need for a Sine-wave Filter

More info

https://hardinge.com/wp-content/uploads/KneeMill-Parts-Older.pdf

Thanks Roy, I had downloaded that previously but links are always useful for anyone else reading this looking for inspiration!

 

[Sideways]

Spot on @Spectric .
A modern phase converter typically doesn't provide a neutral so it is a good thing that the transformer takes it's power from between two of the phases and not phase to neutral.

But yes, with all the primary options, the transformer could just be reconnected to draw from the 240v ac mains.

 

[deema]

Not so fast, the 110v is typical machine control voltage and will not I’m believe be connected to the motor.

 

[Sideways]

With the extra resolution in the photos we can read the thermal overload settings.
The topmost contactor / overload pair are feeding the spindle motor.
The one below is set to supply a much smaller motor of around 150 Watts. That's most likely the X axis power feed.

 

[deema]

Looking at the outside of the control box, the bottom left wires are for the traverse motor, which look to go into the black box inside the cabinet, that would make the black box the speed controller / direction controller.
The upper connector is for the main user switches, so this is the control voltages that will switch the various contactors. So, the larger contactor will be for the main spindle motor as Sideways has stated and the other will be for the coolant pump.

I would expect the light, control voltages and probably the feed motor to all be operated on 110v with the coolant pump and the spindle requiring 415V, 3 phase.

You should get an industrial electrician (domestic sparky won’t have a clue) to basically rewire it for you. Messing around with 415V not knowing what you are doing is a sure fire way of spending the afternoon with the undertaker as Fred Dibner used to quip.

 

[Fergie 307]

Following on from the brief mention in my own introduction the other day I thought I would share, and seek advice, on the re-commissioning of my mill.

A purchase made from ebay between Covid lock-downs which has sat in my workshop ever since. Now, with a bit of time being freed up I looking to get it running.

Pics of it from the eBay auction:

View attachment 190166

View attachment 190167

View attachment 190168

View attachment 190169

And a couple of bits of tooling that came with it:

View attachment 190170

The fun and games of getting it home:

View attachment 190171

Where it sat outside my metalshop (we kinda have a woodshop here too), under the tractor shed with my Harrison Lathe (which will get its own thread), for a month or so while I cleared out all the stuff that had been dumped in it so that I could a) recalaim my space to b) get on with my own stuff:

View attachment 190172

Before getting placed, all be it temporarily for now, roughly where I aim to set it up:

View attachment 190173

With things taking place on the Harrison I've started to think about what will be required on the Bridgeport, and yesterday took a look inside the electrical enclosure...

View attachment 190174

Ahh...hmmm...what on earth is going on in there!?! From the fact that it has powered drives on each bed axis, and a factory option DRO fitted, I'm guessing the MGE Isolating Transformer at the top is providing their 110V supply, but there are dead legs everywhere and that black box floating around at the bottom :/ Hum this might not be so straight forward. Anyone recognise anything????

Supply wise I don't have 3 phase and was thinking of going down a Digital Phase Converter route to supply 415V to it and drive everything through the cabinet as one...now having looked in there...Help!

Lovely old machine, wish I had room.

 

[Spectric]

Not so fast, the 110v is typical machine control voltage and will not I’m believe be connected to the motor.

Yes the motors will be three phase and operated via contactors but all the control and contactor coil voltages will probably be at 110 volts. Fully agree that you need a real electrician with industrial experience and not a domestic have a go type.