It's finally time to power up the ole Bridgeport!

Izzy

Registered
Registered
Joined
Sep 22, 2016
Messages
351
As the title says I've finally saved up a few thousand to get my old bridgeport running! Some of you may remember me but for those that don't here's an overview of what's going on.
About a couple years ago I bought a 72 Bridgeport series 2 for a hell of a deal. It's been sitting in my shop collecting dust while I saved up for the day I could afford a phase converter and transformer! Well that day has come! And I'm looking for advice on how to go about setting this up and what size RPC and transformers I'd be looking at. (A VFD will not work as the mill has 2 other DC drive motors and I'd like to retain all factory features)
The mill has a 4HP 440 3 phase motor. I have 220 single phase. The plan is to go from 220 single to 220 3phase with an RPC then step that up to 440 3 phase with a transformer. I believe I would need a 10hp roto phase and a 15kva transformer. Anyone with experience in this kinda stuff please let me know if I'm atleast on the right path!?
 
What voltages do the dc drive motors use? Would there be any advantage to changing the spindle motor to a 220 volt unit? (cost, simplicity, etc.)
3 phase step up transformers are expensive, heavy to ship and incur losses
mark
 
  • Like
Reactions: Z2V
Just curious and not being a Bridgeport owner myself, you said there are two DC motors also. I’m just wondering if there is a transformer before the DC power supply that is tapped for 220 and 440 volts? If so, is the 4 hp drive motor dual voltage? What I’m getting at is could you convert the machine to 220 volt and save the cost of a step up 3 phase transformer. I know some wiring would need to be changed to larger gauge to handle the higher current of the lower voltage. Like I said, I know nothing about your machine, just thinking through my finger tips.

Oh, I see @markba633csi beat me to the thought
 
I agree, see if the machine can be converted to 220v 3 phase.
Some pictures of the motor data plates, electrical cabinet, etc. will help.
 
Izzy,
you probably do not need to go to a 10hp. 7-1/1 2 will do, but if you are running more than one machine bigger is better. Phase Quest is pretty reasonable for RPC,s. I run two, one 10hp and one 15hp for the last 15 years without much trouble other than a couple switches and bearings in one motor. The 15 hp runs 5 days a week. I also have a step up transformer from 240 volt to 600 volt . I bought it used about 10 years ago for cheap.
Cheers
Martin
 
  • Like
Reactions: rwm
Thanks for all the replies guys I appreciate all the feed back I hope nobody takes this the wrong way but, please stick to my questions. I've already done my fair share of research to know 220 single phase isn't an option in my situation.
@Martin W sounds like what I'm trying to accomplish is reasonable. I plan to build my own RPC that's the cheapest route. As far as transformers go how many KVA would I need? and would it be a bad thing to get bigger than I need? I see alot of 30kva units in my area for like 300 bucks... Just don't Wana buy something that won't work
 
For those that are wondering the entire control panel would have to be re-wired, motor starters, contactors, fuses would all need to be changed, transformers re-wired and finally the motor itself as it's permanently wound for 440. Not practical or economical at all vs just getting it running the way it's supposed to. I want to retain all factory features/fuctionality
 
Is this a CNC machine? A 30KVA transformer would be way overkill, but it would work fine.
 
See I figured 30kva would be alot more than I need but he's only asking 400 for it he'd probably let it go for 300 if I offered. The price is right i just want to make sure I won't let the smoke out of the ole girl before I get to use it!
Lol it's a 1972 Bridgeport series 2. No cnc.
So aside from it being big it would still run the machine?
 
Back
Top