[levig14]

So i will start off by saying this, i am a machining beginner, and have dabbled with it for the past 13 years, but never had a machine of my own. I recently purchased this series II bridgeport from my work. I dont have 3 phase power, and had intended on running the machine with a VFD, i was able to locate one rated for the amperage i need. However i got to wondering how that would all work with the power feeds etc being all integral to the machine. Will they all work? I assume i will have to leave the VFD at 100%, which isnt a big deal since the variable speed works fine on the mill. Am i missing something here, or should i have gone with a rotary phase converter instead? Here are some pics of the machine for reference.

[CNCMAN172]

I would use a rotary phase converter, a VFD is really designed to change the speed of a motor electronically. The rotary phase converter will just output three phase which is what the mill really wants.
Russ

[levig14]

I would use a rotary phase converter, a VFD is really designed to change the speed of a motor electronically. The rotary phase converter will just output three phase which is what the mill really wants.
Russ

I agree that a phase converter is the best possible choice, but for now i am hoping to just get it up and running. Do you think the VFD will allow it to run until i can source a converter?

[CNCMAN172]

On most of these older machines, the only thing that really uses three phase is the spindle motor. Did not see the voltage plate for this machine, but you might be able to run the spindle from a VFD and then the rest of the machine on single phase power.

Russ

[levig14]

On most of these older machines, the only thing that really uses three phase is the spindle motor. Did not see the voltage plate for this machine, but you might be able to run the spindle from a VFD and then the rest of the machine on single phase power.

Russ

Now that sounds like a deal! I am not sure what the motors for the power knee and other power feeds use, i will have to take a closer look when i get away from my desk a little bit later and see what its got going on in the huge electrical enclosure on the back of the machine. The only voltage tag i could find on the outside of the machine was the voltage tag on the spindle motor.

[CNCMAN172]

There should be a voltage and power plate on the control box for the machine as well. Open up the box and you can trace the cable that goes to the spindle. Normally you will find a power supply inside the control box and you will be able to confirm the rest of the machine runs from spindle phase. This is really pretty common, but with a little leg work you can confirm that is your situation.

Russ

[Al_The_Man]

I converted a few XLO mills very similar to the BP. I took the vari-speed off and fitted a 1:1 pulley to the spindle and fitted a VFD.
The XLO also had a 2 speed G.B. which made it useful for very low rpm's if needed.
Can't beat a VFD, IMO.!
Al.

[levig14]

I converted a few XLO mills very similar to the BP. I took the vari-speed off and fitted a 1:1 pulley to the spindle and fitted a VFD.
The XLO also had a 2 speed G.B. which made it useful for very low rpm's if needed.
Can't beat a VFD, IMO.!
Al.

This machine has a 2 speed gearbox as well. I may in the future remove the variable speed if it starts giving me trouble. At the current time i am just trying to make sure i get it all wired up so all the power feeds and power quill work as they should. I am hoping for the situation that Russ mentioned below in which the remainder of the machine runs off of single phase power and the hookup should be easy!

[CNCMAN172]

Post some pictures of the inside of the control box and you can usually determine if the rest is on single phase.
Russ

[levig14]

Post some pictures of the inside of the control box and you can usually determine if the rest is on single phase.
Russ

You got it, i will crack it open over lunch and snap some pictures.

[Al_The_Man]

Generally there is a 1 phase control transformer that feeds the controls etc.
I think I have the schematics somewhere for that machine.
The 1ph control transformer usually has a 220/440 taps on the primary for running the controller.
Al.

[levig14]

Generally there is a 1 phase control transformer that feeds the controls etc.
I think I have the schematics somewhere for that machine.
The 1ph control transformer usually has a 220/440 taps on the primary for running the controller.
Al.

Our machine shop maintenance guy just brought me a bridgeport schematic that he said he believes goes with my machine, it appears it does indeed show a transformer pulling it down to single phase for everything but the spindle motor. I will open up the box over lunch and see what i come up with .

[Al_The_Man]

The (1ph) transformer is fed across 2 phases, if it has a 120v secondary, one side should be earth grounded to re-establish a neutral.
Al.

[bill south]

I have a Bridgeport Series 2 (older manual machine) and run it all the time with a Hitachi VFD. I just sized the VFD for the motor HP and use both the head speed change and the VFD for speed control. Never had an issue but maybe the machine doesn't know where it's plugged in (??).
Hope this helps and good luck.
Bill

[levig14]

Here is the control panel. My intent is to disconnect the right side of that transformer and feed it directly with 220 single phase from my garage, and then wire directly to the spindle motor with my VFD, bypassing the motor contactors. Does this seem like the right way to do it?

[CNCMAN172]

Levi,
I would make sure the machine is unplugged and follow the third phase around I can see two sets of fuses for three phase. Looks like it feeds directly to the transformer or contactor directly below. The fuses on the left side feed the Black box is that a transformer it is hard to tell in the picture. But you should be able to verify only the spindle is running on three phase, if so you can do as you suggest.
Russ

[CNCMAN172]

Levi,
Take the schematic that the maintenance guy provided and see if it really matches what you have. That is a great way to get started. Other will have the schematic if that one does not match exactly. Once you have that you can see exactly where the three phase power is converted and how to separate the spindle from the single phase power requirements.

Russ

[levig14]

Levi,
I would make sure the machine is unplugged and follow the third phase around I can see two sets of fuses for three phase. Looks like it feeds directly to the transformer or contactor directly below. The fuses on the left side feed the Black box is that a transformer it is hard to tell in the picture. But you should be able to verify only the spindle is running on three phase, if so you can do as you suggest.
Russ

I just went and looked at it again, the one line from the 3 phase runs down and through a "loop" i assume this is where they are reading the amperage off of the line in order for the loading meter on the front of the machine to read. Otherwise all the 3-phase wires just go to the contactors for the spindle motor. Looks like i should be good to go to isolate the transformer and power it up with 220 single, as well as power up my vfd with 220 single. The only thing i will lose is the ability to turn the spindle motor of and on with the machine control panel, but thats no sweat off my back. Thanks for all of the advice you guys!

[Al_The_Man]

It looks like a 1ph transformer, a pretty hefty one, I would guess at least 1.5Kva.
You should use proper control practices and use the contactor for the VFD input side for the E-stop circuit.
You can by pass the 3rd phase and modify the input supply for 240v 1ph, just use 2 of the phases for the 240v circuits.
Why can't you integrate the motor control buttons to control the PLC low voltage input to the VFD?
You can run wiring to a pot for rpm control.
NFPA79 example.
Al.

[CNCMAN172]

Levi,
Please check your schematic closely, as the one Al the Man posted shows a three phase hydraulic pump, make sure you don't have that situation or you will need three phase for that pump as well.

Russ