New (Old) Bridgeport HELP!!

Michael J. Spangler

Michael J. Spangler

Joined
Oct 8, 2003
Messages
2,181
Hey guys... i just unloaded a bridgeport into my show courteousy of TBlade

you rock man! thanks again


now i need a new motort for it, because it has a 220 3 phase on it. i need single phase.

might have to cut a small hole in the ceiling to get the sucker to fit right too.... damn me for insulating the shop and putting ceilings up.

any suggestions or resources on getting a new motor and fixing her up and general re build info ? thanks again guys !! merry christmas
 
Hi Mike,
It might be worth the research into finding out how to make a rotary phase converter. Or at least a cost comparison of one to the cost of having to changing motors on your Bridgeport.
Does your Bridgeport have a 2j head?
 
:
loussharp1 said:
Hi Mike,
It might be worth the research into finding out how to make a rotary phase converter. Or at least a cost comparison of one to the cost of having to changing motors on your Bridgeport.
Does your Bridgeport have a 2j head?
Click to expand...

Yes it does have a 2j head.
and mike didn't just unload my father in-laws bobcat had a big part not to mention his brother in-law(jerk). Also he forgot to mention that when he told me he couldn't feel his fingers and I gave 'em a good slap. He could feel them for the record:D
Paul
 
You guys SUCK!
I am sooooooooooooooooooojealous!

Get a three phase converter rated for at least 10% more HP than your motor, and make sure you have enough current to your barn to run it. If you're still running a generator for power make sure you have enough coming from the generator to cover your conversion losses.

-Page
 
we do have the shop wired now... plenty of juice to run it.

i figure it'll be cheaper to buy a new single phase motor than bother with an expensive phase converter. i hear the static ones suck and the rortary are pretty pricey

thanks for the helps guys keep it coming
 
I use a static phase converter on my Bridgeport, even though I have run three phase power into the shop. It was just simpler that way, it works 100% just fine and the static converter is super simple and inexpensive.

Additionally, you will be very hard pressed to find a replacement motor for the Bridgeport that is as well balanced, well built and vibration free as the original. You may pay a penalty in surface finish if you change. Plus, three phase can be instantly reversed with a reversal of the switch, while single phase has to come to a stop first. This is important if you do any rigid tapping from the spindle (I do). The torque of a Bridgeport in backgear rivals that of my big mills, so it can turn big taps in stuff like 316, but it does help to be able to reverse on the fly.
 
Nathan the Machinist said:
I use a static phase converter on my Bridgeport, even though I have run three phase power into the shop. It was just simpler that way, it works 100% just fine and the static converter is super simple and inexpensive.

Additionally, you will be very hard pressed to find a replacement motor for the Bridgeport that is as well balanced, well built and vibration free as the original. You may pay a penalty in surface finish if you change. Plus, three phase can be instantly reversed with a reversal of the switch, while single phase has to come to a stop first. This is important if you do any rigid tapping from the spindle (I do). The torque of a Bridgeport in backgear rivals that of my big mills, so it can turn big taps in stuff like 316, but it does help to be able to reverse on the fly.
Click to expand...
I have heard good things about static converters form the folks who use them.
Most of the guys I know who made homemade rotary convertors have said something about losing one leg of the phase, I think that may be because they didn't do it properly, One thing I would expect from a rotary regardless of how it is built is a 5% speed loss due to field slippage (which is why most AC motors run at 1720 RPM instead of 1800 which would divide nicely by 60Hz)
I believe static converters actually maintain your line frequency. You will have some power loss in conversion (nothing is ever free) but as long as you spec everything appropriately you should have no problems. Nathan is right about Bridgeport motors. If you have one and it is in good shape get the converter, any other choice you will regret.

-Page
 
PMLKnives said:
we do have the shop wired now... plenty of juice to run it.

i figure it'll be cheaper to buy a new single phase motor than bother with an expensive phase converter. i hear the static ones suck and the rortary are pretty pricey

thanks for the helps guys keep it coming
Click to expand...

You can get a variable frequency drive for $150 to $350, depending on the HP needed and not use it to change speeds. They advantage is it will provide full power and that may help at lower speeds on hard cuts. I don't think you will need a NEMA-4 box on it if it isn't near the grinders and even then, the VFD can be set up in a filtered box to protect it.

Mike
 
hey guys thanks for the info. Looks like i'm going to go with the statica phase converter.

147 bucks and i can pick it up about a half an hour away from home.

From what nathan said and what RJ Martin said, i won't have an issue with it

its actually the variable speed model, not a belt driven. pretty damn cool.
it has a powe feed but i have no clue if it works, i do know it needs a new fuse and cover for the fuse.

found a few cool things inside it too... a nice indexable mill. and a slitting saw arbor.

not to mention some cool pieces of history that i'll do a seperate post with later. you're all gonna love this.

i'll post some pics on this beast later. thanks again guys!
 
Mike, Congrats on your new machine.!!!
I'm running my 1952 on a static phase converter that I picked up for about $125.00. It works great.... Hope you don't have to get it down into the basement like I did....:barf: I wasn't sure if I would get it back together ..:rolleyes:
 
I used a static converter for years on my knee mill. I worked great but now I use a VFD and it works fantastic. It is much cheaper and easier to go with an inverter than buying a 1ph motor then mounting it. If you have ever taken apart a bridgeport head it can be a PITA.
 
well i picked up all the wiring and phase converter stuff yesterday.... just need my electrician to give me a hand with it sometime this week.

man this is a beastly mill... i don't know where the hell to put this thing... i think it might go in the middle of the shop... easy to work around it.

i'll keep up with some updates and pics as soon as i remeber to bring my camera to the shop with me. thanks for the help guys
 
Congrats on the new machine! I hate to be a party pooper...but I will never..ever...ever recomend or suggest using a static phase convertor unless you fully understand what it is and how that specific brand works. I used a Phase-a-matic many years ago and found that my 1hp BP had very low power....and in a few days....I smoked the motor during a long cut. After rewinding the motor and taking the time to study the Phase-a-matic....I was dissaponted to learn that it is only a capicitor used to start the 3 phase motor...once the motor is started..the capacitor drops out and your 3 ph motor runs on a single phase...single winding. This can be easily confirmed if you use an amp meter to measure the current on each leg. So, basically, a 3 phase motor with 3 sets of windings ends up running on 1/3 of it's potential. ..and 1/3 of the power. I think Phase-a-matic is creative in their marketing...and after enough phone calls to thier techs...I built a rotary unit and tossed the Phase-a-matic in the trash. I tinkered with my 3 hp rotary unit for about 5 years...before eventually outgrowing it. Then replaced it with a big honking 10 hp unit from a commercial manufacturer. The rotary units ran fine...but they were never perfectly balanced across all three legs in terms of current draw. While this was never a problem..I always thought about it. Then I tried my 1st VFD. Theyt are nearly perfectly balnaced across all legs and produce very stable current. Alog with the VFD, you get all sorts of cool features such as dynamic braking, speed control, instant reversing, ...and most importantly, you get motor overlaod protection.

If I were to ever do it again, I would use a VFD.


Let's talk a little about industrial motor protection. Due to the high current surge required to start motors, they are generally over fused so that the fuse doesn't blow during start-up. Being overfused, doesn't protect them from overheating during a continous hi load. So, for motors you need 2 types of protecting...Short Circuit and Overload. Short circuit is a fuse or breaker used to prtect the wiring in case of a short circuit. This keeps from burning your shop down.
Overload is when the motor runs under a hi load for a long time..until it just gets too hot and "melts-down". Industrial motor starters with thermal overload have specifically sized heater elements which cause the starter to disconnect in an overlaod situation. Many single phase motors have a thermal overlaod button that you reset when the motor is overheated...but 3 phase motors do not and need protection. You get this with the VFD..or a 3 ph motor starter. Consequently, by the time you buy a motor starter and fit it with the appropriate heaters for your motor..along with a static phase convertor ..with wiring hardware..you'll probably exceed the cost of a VFD. And it is my opinion that the VFD with offer more performance, more protection and more useable features for less cost.

I'm not sure if this made any sense...I hope I don't sound negative..it's just that I was terribly dissapointed from my experience with a static phase convertor and since then, and after needlessly tossing money down the pipes...I feel that there is a much better solution.

Good luch with your New (old) Bridgeport! What a wonderful machine!!

Sincerely, Rob
 
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