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Setting up a Bridgeport mill VFD?

beeser

Cast Iron
Joined
Jan 3, 2015
Members writing in the Bridgeport and Hardinge Mills and Lathes forum suggested this forum for help in using a VFD for my 2hp Bridgeport mill. The consensus was that a VFD was better suited than a rotary phase converter. So, simply put which VFD should I buy for a 240VAC single phase power source? I have a large Oneway woodturning lathe that uses a VFD for its 3hp 3 phase motor. It's in an enclosure with power on/off push buttons on the outside. I would like to duplicate that setup if possible rather than leave the VFD exposed. My apologies if his sounds like a lazy request but my attempts at trying to find a VFD from online vendors met with questions I couldn't answer. Also, will a VFD allow me to use the existing Hi Lo switch on the mill to start and stop it?
 
This is what I had in mind for the VFD installation except wall mounted and the light, on/off buttons on the front door panel. The VFD is a Yaskawa GPD 315/V7, which I don't know is appropriate for the 2hp Bridgeport mill.
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This one is what I recommend. I have hundreds of these in use currently and have use on Bridgeport's as well. Forward/Reverse and speed control at your fingertips. KBAC-27D 2HP VFD 115/23�VAC GFCI 9667

Thanks! I think that has everything wanted; on/off, power indication, forward/reverse and the enclosure. Probably a dumb question but does this eliminate the need for the switch on the mill? If so, does the VFD get wired directly to the motor bypassing the existing switch?
 
Thanks! I think that has everything wanted; on/off, power indication, forward/reverse and the enclosure. Probably a dumb question but does this eliminate the need for the switch on the mill? If so, does the VFD get wired directly to the motor bypassing the existing switch?

Wiring the motor directly to the VFD terminals is the best way, yes.

The drives have all the low-voltage logic inputs available to let you wire control switches in a number of different ways.

My approach is to install a small box with a variable speed knob and small three position toggle switch, fwr/off/reverse. At first
glance one might want to employ the original drum switch, but there is rarely room for the variable resistor to set speed inside that
enclosure.

If you are really invested in the original drum switch for whatever reason, you can always mount the speed control knob in a small
nearby housing. Having the switch and variable resistor in one box has the advantage that all of the low voltage logic wiring
comes out of one enclosure and goes directly the VFD inputs, all in one cable. No need to joint up the wires from two different
boxes.
 
Thanks! I think that has everything wanted; on/off, power indication, forward/reverse and the enclosure. Probably a dumb question but does this eliminate the need for the switch on the mill? If so, does the VFD get wired directly to the motor bypassing the existing switch?

Yes, it has it all but as they come they do not have all the switches. You will need to order some them separately. I would just get the forward/reverse switch and it comes with an on-off switch for the drive. Call the guys at Electric motor wholsale and they will be more than happy to walk you through any questions you may have.

Anyways yes bypass the drum switch as you do not want anything between the VFD and motor. I mounted my vfd off the side of the column on a swinging bracket so it is all right at my fingertips when needed and can be pushed back when not needed. My DRO was also on this bracket as well.
 
Although I have never seen that KBAC unit, it's WAY overpriced and has few stated features. Who really needs a washdown enclosure..a milking barn!!

If your mill has an existing drum switch, keep it. It will be used to switch the logic inputs to the drive, not the motor leads. This will give you your instant FWD/REV without screwing with a toggle switch. As Jim mentioned, find a small plastic hobby box or enclosure and mount the appropriate speed pot in a handy place next to the directional drum switch.

All you need as an operator is FWD-OFF-REV and a pot for speed control.

Your picture shows a contactor in the enclosure...what's that for?

Stuart
 
Although I have never seen that KBAC unit, it's WAY overpriced and has few stated features. Who really needs a washdown enclosure..a milking barn!!

If your mill has an existing drum switch, keep it. It will be used to switch the logic inputs to the drive, not the motor leads. This will give you your instant FWD/REV without screwing with a toggle switch. As Jim mentioned, find a small plastic hobby box or enclosure and mount the appropriate speed pot in a handy place next to the directional drum switch.

All you need as an operator is FWD-OFF-REV and a pot for speed control.

Your picture shows a contactor in the enclosure...what's that for?

Stuart

I don't know the purpose of the contactor. The Oneway woodturning lathe has another enclosure for the operator with controls for on/off, speed control and emergency stop. The machine is exceptionally well built and works perfectly.

Another dumb question - Since my Bridgeport has the mechanical variable speed control, why do I need another speed control on the VFD?
 
Although I have never seen that KBAC unit, it's WAY overpriced and has few stated features. Who really needs a washdown enclosure..a milking barn!!

If your mill has an existing drum switch, keep it. It will be used to switch the logic inputs to the drive, not the motor leads. This will give you your instant FWD/REV without screwing with a toggle switch. As Jim mentioned, find a small plastic hobby box or enclosure and mount the appropriate speed pot in a handy place next to the directional drum switch.

All you need as an operator is FWD-OFF-REV and a pot for speed control.

Your picture shows a contactor in the enclosure...what's that for?

Stuart

Okay Buba!
 
beeser,

Here are some thoughts from "Buba"!

It sounds like your main focus is using a frequency drive to create 3 phase for you mill in a single phase environment. Most drives will do that..take a look at a WJ200 Hitachi, it's half the price of Mr. Mathews KBAC unit and probably has twice the features.

If your Hi/Lo is actually a two speed motor then that won't play well with a frequency drive, they need basic parameters set for ONE motor only.

You could adjust your vari-speed to a middle or medium speed, leave it there and use the drive to vary speeds from a pot for daily use. Keep in mind the drive allows all kinds of other features like quick braking, instant reverse for tapping and overload protection for the motor.

If you want to retain the features you have right now on the mill and are merely after a 3 phase source, you could use the drive for that too. You would really be shorting yourself on the bells and whistles though.

I ran my Bridgeport clone on a static converter for years and it worked perfectly. These are frowned on by many folks but the work very well for a budget project.

Look at different drives and study their features and compare prices. I would buy mainstream and would stay away from some of the Ebay Chinese jobs..although they seem to be getting better they still can't compare to brand names like Hitachi, Teco, Weg or TB Woods.

Stuart
 
I would just like to throw out my 2 cents worth. I remember having all the same questions as beeser when I first started working with vfd's about 13 years ago. I was doing some water well work and they were just becoming popular in that industry. They were also as big as a house back then and cost damn near as much!
That yaskawa drive setup in that picture is really a good drive. They are very well built and you will start to see more of them as there prices come down. In my opinion a yaskawa drive might be overkill for the needs of a lathe or a mill. I have been using ABB drives for years but programming has always been tough on those guys. I will probably switch to yaskawa as they are s'more end user / programmer friendly. For small motors like on mills and lathes there are a lot of options available. Almost any VFD with the right ratings will have all he functions necessary for shop equipment. The main concern that I think is important is heat in the motor. Once you have a VFD set up you will probably rarely run the motor at a full 60hz and because the motor won't be running full speed the heating charictaristics will be different than what the motor was designed for. Adding a simple fan to the motor will solve that issue.
I recently rebuilt an old step pulley Bridgeport with the original pancake motor and used a Westinghouse teco drive. Very inexpensive and it has more features than a mill would ever need. The control panel can be as simple or as complex as you want. Here is a picture of a simple control panel I built for this mill. I also installed a small low voltage fan above the motor so I never have to worry about heat issues when running at slow speeds for long times. image.jpg
 
I can't specify which unit I've got on mine without breaking forum rules (LOL) but I will say that I wall-mounted mine and then have the power and the remote display/control mounted where the original rotary switch was on the motor. Mine is a '46 so the wiring was a little suspect to be moving around much so I turned the rotary switch enclosure into a junction box and used hook and loop to secure the remote control/display.

It works well, the controls are right at my fingertips. I have a braking resistor to hook up one of these days and I'd like to put an E-Stop on it.
 
If you not concerned with functions supplied by a VDF why not make an RPC? I have a Cincinnati ToolMaster vert. mill with the Bridgepoert type head and the powered overarm (A spindle driven by gearing and a motor inside the ram) I have been running it now for over 5 years on a simple homemade RPC. All I have is a 3HP Delta connected motor and a means of starting it with a capacitor. Nothing mote! Motor is 1200 RPM (synchronous speed not nameplate) The ToolMaster is a bit more heavier duty than a Bridgeport and I do push it to removed as much material as possible. I'm usually cutting SS. 3 phase motors are easy to find thought the type I have will not be as easy but I'm thinking a standard 3 phase motor will be just as good or at least good enought until you find a better motor! Motors in the 1700ish name plate RPM should not be hard to find but stay away from the 3500ish. Finding a capacitor and a contactor to start the motor should not be hard either. Will keep quite a few hundred in your pocket unless you opt for Brand X that's against the rules here and done so for good reason!
 
My 660V 3 phase Bridgeport is run by a transformer to boost 240 to 600 single phase which is fed to an old AB vfd. This was preferable to building a rotary phase converter as I did for my HLV-H. Both methods have their place but the VFD is both easier and gives very good motor protection when appropriate limits are set. A VFD is simply easier to use and easier on the equipment.

I was using VFD's in mining since the early '90s and would always given a choice use one instead of other versions of speed control available to me. My basic approach was up to 20 hp, a line starter if feasible and 20+ hp always an electronic soft start or VFD as appropriate. Most of my small hp applications had see belts such as conveyor drives to absorb start up shock.
 
Anyways yes bypass the drum switch as you do not want anything between the VFD and motor.

This is correct that there shouldn't be anything between the VFD and the motor. You can add switches and protection upstream of the VFD but down-stream can cause problems.

That being said, if you WANT to use the drum-switch (for the nostalgia or other reasons) there is no reason you cannot wire the VFD directly to the motor (bypassing the drum switch) then wire your FWD/RVS control wires into the drum switch. IMHO, less useful on a mill, but on my long-bed lathe, I have a switch-rod that controls a drum, there is a switch lever on the apron as well as the head-stock and the switch-level also controls the electromagnetic brake system. It was important for me to maintain switch functionality with the addition of the VFD. So the drum switch now controls inputs to the EM brake system and the FWD/RVS inputs to the VFD.

I also saw mention of de-rating. Generally, if a VFD is listed for 1-phase input it has already been derated. If it only lists 3-phase input and you're going to be supplying 1-phase then you need to #1 De-rate, and #2 Make sure you can turn off any phase-loss protection or monitoring the VFD may have. IE, my big lathe runs a VFD that is only rated for 3-phase input (IIRC it's a 10hp VFD on a 5hp motor). That's because it's hard to find VFDs rated for 1-phase input in that size. No problem, I just used the menu functions to turn off the phase-loss protection and it works great on 1-phase input.
 








 
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