converting bridgeport to single phase

[williamy]

hi,new user here,just got a used bridgeport and would like to put single phase motor on it,anyone have any information on conversion

[Thrud]

You can do this one of two ways. 3Phase motors produce smoother output and more horsepower for the same physical size.

Replace the motor.

Get A Variable Frequency Drive for it (VFD) they still require 220/240v some can be driven from single phase, other cannot. Ask when you inquire into it. Normally a unit wil give you full variable speed and many models offer torque boost and increased speeds as well. Worth considering.

[williamy]

I think the way I want to go is a new motor,the problem is I can not find a single phase motor.It is a145ty-4 frame and I have not had any luck locating one.I did find a referance in the home shop machinist archives to a article in the 1996 december issue written by schultz on page 40 that could be what I am looking for but I have not had time to check it out,if anyone knows of this article maybe they can reply,and I can persue it further. p.s. thanks for the reply

[SGW]

Seriously consider the VFD route. (See for example http://www.dealerselectric.com/ or http://www.vfds.com/ or several other suppliers of surplus drives.) It probably won't be that much more expensive than a new motor, and I think you'll really like the variable-speed capability.

[williamy]

Got a Teco-Westinghouse FM100 fluxmaster,but have been told it only works on 3 phase and is more or less a speed control not a phase converter,it is listed as a frequency inverter not a phase converter

[iamrocketman]

if the present 3 phase motor is good keep it because it will run smoother with more torque and instant reverse capability(for power tapping).Run it and any other machines that you may acquire from a ROTARY PHASE CONVERTER which can be built from articles previously published in HSM. DO NOT waste your time and money (and motors) on so called "static" converters which are nothing more starting circuits which cut out at running and leave your 3 phase motor trying to develop rated power from single phase input(burn out time here). There are many designs for these. The good ones use electrolytic motor starting capacitors to start the idler motor and oil filled running caps. to smooth out and boost the voltage output.Purchased converters are all overpriced and many do not have the proper electrical circuits in order to save costs. Stay away from VFD INVERTERS unless you are in to electrical engineering because although they are excellent drives they are expensive and complicated to buy, set up and run requiring lots of electrical circuits for there proper use.

[Indexer]

williamy

I have a couple of Mitsubishi VFDs in my shop and contrary to rocketman's assessment of VFDs, I found hooking them up to be easier than wiring in a standard motor, of whatever flavor. Two single-phase 220 V wires and a ground going in from the house supply, three 3-phase wires and a ground out to the motor. That's all that are required. You might want to add 3 light-weight, signal-type wires to a remote FWD-STOP-REV switch and 3 more to a remote speed control potentiometer, but they are just added convenience rather than necessary. They can also be operated easily from a front-mounted numerical keypad. The only trick is that you will need to double the power rating of the VFD you need to get if you are using single-phase input rather than 3-phase input. As already noted, the smoothness of operation and the convenience of finely-controlled motor speed make this approach the overwhelming favorite. The cost of last year's 'obsolete' models is generally very reasonable, especially if you can save the cost of buying a new motor. Check out the sites in SGW's post.

At issue here is more than just that your mill will be more the pleasant to be around when it is running. With the 3-phase motor you will do better work because of lower motor vibrations, and with the VFD, speed control is easy enough that you'll actually use the right speeds and feeds rather than the settings left over from a job or two or three ago. The difference will be visible in the finish of your work.



------------------
Rich Kuzmack

Pi = 355/113 . . . to
<85 parts per billion

[John Stevenson]

<font face="Verdana, Arial" size="2">Originally posted by iamrocketman:
Stay away from VFD INVERTERS unless you are in to electrical engineering because although they are excellent drives they are expensive and complicated to buy, set up and run requiring lots of electrical circuits for there proper use. </font>

This has to to be one of the most INACURATE statements I have heard.
The cost of these is rapidly coming down especially as the manufacturers dump the last model. Setting up is very easy. I have a 16 year old apprentice who does these no problem. They are quiet, instant reversing, soft starting and braking and so smooth.

You need far more electrical knowlege to built a rotary convertor than to take an invertor out of a box.

As for lots of electrical circuits the onboard models require 2 single phase in and 3 three phase out wires.
The remote models require the same plus 3 wires for the speed pot, a common, reverse, start and stop. A total of 7 wires all at 10v 10mA for safe working.
I don't call that lots.

Over the last two months I have sold off a lot, read about 80, old model invertors to the UK model engineers from a job lot I bought. So far no one, repeat, no one has emailed or phoned to ask for asistance in setting these up.
All I get is referal phone calls for more.

John S.

[SGW]

I sure didn't have any trouble setting up mine to run from the VFD's front panel controls...that's trivial. It did take a little effort to sort through the complete but obscure manual to find out how to wire the remote pushbuttons and speed control, but nothing horrendous. 3 pushbuttons and a 10K potentiometer from Radio Shack, and a length of leftover CAT5 network cable, isn't really complcated. If you're content to forego the remote switches and just run off the VFD front panel controls it is really trivial.

[JCHannum]

Nov/Dec HMS has no article on Bridgeport motors. Page 40 is part of article by George Genevro on two cycle motors.
The reason you cannot locate a single phase motor for Bridgeport is that it is most likely a custom made motor for Bridgeport. Special mounting flange, extended shaft and probably special bearings.
I agree that the best arrangement is a VFD. Even if a single phase motor were available, a VFD would probably be cheaper, and offer far more benefits than a plain motor can provide.
No difficulty in hookup. Some difficulty in translating some of the manuals from Japanglish or Taiwanglish to English though.