# Replace Rotary Converter With VFD?



## Mingybear (Jan 3, 2015)

Hello and thanks in advance.

I was given a 2HP Bridgeport Mill. The nameplates, etc., have been removed so I don't know what model it is. I have a manual for a Bridgeport Series One Model BRJ or BR2J2, but I don't know for sure if that is the machine I have. It is disassembled so there might be parts missing, but I am not sure. I know I am missing the coolant tray and pump but that is easy enough to deal with. I guess since the machine was being used to machine EDM electrodes it didn't need coolant.

The motor is a 2HP 3PH wired for 440 Volts. I am pretty sure I can rewire it to 220 V as the instructions are on the motor nameplate. I have not been able to locate a direction control (reverse) for the motor. The only switch appears to be a honking big AC knife switch in a box connected to the motor with a 1" diameter cable that looks like an extension cord. 

Speed control is through a big belt and a continuously variable transmission (CVT).

My brother, who gave me the machine, bought a 2HP rotary phase converter for it. He paid $329 for it and it is brand new, never been installed. Based on the thread here, it seems to me a VFD would probably be a better option, especially since the forward/reverse controls are integral to the VFD (as I understand it).

So, I am thinking of selling the 2HP rotary converter and replacing it with a VFD. Based upon what I have seen, a TECO FM50-203X seems to be one option, but there may be others. I hope to eventually get a metal lathe, which may or may not be 3PH, but if I do it is extremely unlikely I'll run both machines at the same time.

Can anybody recommend a suitable VFD for my situation? I am willing to pay a little extra if there is a reason to.

Thanks


----------



## CluelessNewB (Jan 3, 2015)

Personally I would look for a sensorless vector VFD rather than a volts/hz like the FM50.   The TECO EV/JNEV Series will provide better low speed performance for a few $ more.   Horsepower rating will get you close but double check the check current rating (amps) on the motor and use that to select the correct size.  You can go bigger (like a 3hp for a 2hp motor) but not smaller.  

Using a VFD for multiple machines can be done but typically you will want to program the VFD for a particular motor parameters and set of controls, moving from one to the other would be a royal pain!


----------



## Reeltor (Jan 3, 2015)

I'm a fan of RPC's; buy it once and use any number of 3-phase machines through it.  I setup a RPC, hooked up the lathe, then a year later bought the mill (it has 2 3-phase motors) and now hooking up a shaper.  So for me it's cost effective to go with one RPC.
I don't have any experience with a VFD; so I may be way off base.  I have read on here where people are using a VFD for multiple machines but like CluelessNewB said, you need to program the VFD for a specific machine.  For now; I'd keep what you have and see how it goes.


----------



## Karl_T (Jan 3, 2015)

Here's the one I'd buy:
http://www.automationdirect.com/adc...ts_(115_-z-_230_-z-_460_-z-_575_VAC)/GS2-22P0

This vendor has great service, good pricing. you might find cheaper, but lose some on service.

I'll suggest you get a brake resistor, this allows fast stopping.

I also think a for forward/stop/ reverse switch is super handy. same goes for a remote speed pot.

many threads on how to wire this, or just ask.

edit
here's mine
http://www.hobby-machinist.com/showthread.php/27040-VFD-control-box


----------



## ranch23 (Jan 3, 2015)

My electrician ran my RPC into a separate 3 phase breaker box. Then wire up machines as normal.


----------



## Hawkeye (Jan 3, 2015)

I used a Teco FM50 rated t 2 HP to run a ZX-25 mill and a Hercus AR 9" lathe, interlocked through a relay system that wouldn't allow changing machines unless the drive was stopped. One machine had a 1725 RPM motor and the other had a 3450. Both were 1 1/2 HP. I never had any trouble with either motor. The system was a dream to use. The control head was on a telescoping swing arm to put it in the right location for either machine. That's a MachTach display for RPM - switches inputs when you change machines.


----------



## Mingybear (Jan 3, 2015)

Thanks for all the replies.

It sounds like a VFD is a good option for me, especially since my mill seems to be missing the electrical control set up (in particular reverse).

I'll have a look at the recommendations.

Thanks again.


----------



## rdhem2 (Jan 4, 2015)

A VFD is an excellent way to go for many reasons.  Don't let the start up costs scare you off as they will be regained if and when you ever sell the machine.  Actually a good selling point as the next hobby machinist will not have mess with it.  I have a SqD/Telemecinique on my Bridgeport mill and I love it.  I use the original vari-belt system for speed control but use the drive for all else.  single phase to three phase, soft start, soft stop, (2sec or less), overload control, voltage monitoring, forward/reverse and on and on.
You will find that most older mills come with only a drum switch to control forward/reverse.  Newer ones by code will have overload protection of some sort.  Enjoy your new machine.


----------

