# VFD for Bridgeport Mill



## L Machine

Hi all,
 I'm new to this forum. I'm sure I'm asking questions that have been asked a million times before. I just bought a variable speed (little crank to control the spindle RPM) 2 HP Bridgeport mill. I want to run it off of a VFD because it's cheaper than buying a RPC. I know ZERO about electicity (except that it can kill you and burn your house down). How do you hook up one of these devices? Can the original controls on the mill still be used? Can it be used strictly as a phase converter? I've read that the up and down arrows are used to control the speed of the spindle. How is this practical and how do you know your spindle RPM? I need this explained as if it was being taught to a caveman who knows nothing about electricity (no mumbo jumbo). Thanks


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## Tony

L

I have the setup that you are considering and it works very well for me. I can send you the wiring diagram for my setup. First thing is to check that the 2hp motor is setup for 220V or 240V 3 phase power. The motor I got with my mill was orrigionally wired for 575V 3phase. I had it rewound for 220V 3 phase for me it was the easier way to go the other option would have been to get a sep up transformer to go from 220 to 575.  Do you have a VFD yet? If not you want to look for one that is either rated to run a 2hp 3 phase from 220 single phase or rated to run a 3hp Motor.

I'll attache the wiring diagram when I find it.
T


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## L Machine

Tony, thanks for the reply. So you can still use the original factory controls (FWD / OFF / REV and teh speed adjustment crank) with your set up? I know a lot of people use the up and down arrows on the VFD to control motor speed, starting and stopping. I just don't understand how spindle RPM is determined. It sounds like a big pain in the butt. I'm hesitant to buy a VFD. Not sure which to buy. Which VFD do you have? My motor is 2 HP, 3 phase. the info plate lists 220, 230, 440, and 460 volts. Thanks..


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## Tony

L

I use the VFD to control forward and reverse and the mill's variable speed to control cutter speed. There are no switches between the VFD and the motor, VFDs don't like external switches on the 3 phase lines into the motor. I removed the 3 phase switch that came with the mill.  I have a single phase 220v switch that feeds the VFD, that I use as my main power switch.

Tony


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## L Machine

Thanks Tony. What make/model VFD do you have? 

M


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## Tony

L 
VFDs control motor speed by controlling the frequency of the 3 phase power that is applied to the motor. In North America the power comes into the house or factory at 60Hz (Cycles/Second). 60Hz is where most motors and mills are designed to work, not that they won't work at other frequencies, the RPM indicated on your mill's dial is based on the motor being run at 60Hz(assuming you have the original motor or one just like it). If you set the VFD to output 60Hz then the RPM on stated on the mill will be correct. That's the way I run it because I have the variable speed drive in the mill head. For those with mills where you have to move belts to change cutter RPM it's easier to change the VFD frequency. The thing to watch out for if you are changing the speed with the VFD is motor cooling.  The fan built into the motor is designed to run at the nominal motor speed. When you slow the motor down with the VFD the the fan runs slower, you get less air flow, and chance that the motor will over heat increases. Many have installed external fans that run independant of motor speed to over come this.

Page 11 of the attached PDF shows how I have mine wired.  I used only the R & S input terminals for single phase power as stated in the note.

 My VFD model # is FR-A-220E-2.2K  (2.2KW = about 3Hp I run a 2Hp motor from the 3 Hp VFD)

Tony

http://www.hobby-machinist.com/downloads.php?do=file&id=81


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## shaskell

L Machine said:


> Hi all,
> I'm new to this forum. I'm sure I'm asking questions that have been asked a million times before. I just bought a variable speed (little crank to control the spindle RPM) 2 HP Bridgeport mill. I want to run it off of a VFD because it's cheaper than buying a RPC. I know ZERO about electicity (except that it can kill you and burn your house down). How do you hook up one of these devices? Can the original controls on the mill still be used? Can it be used strictly as a phase converter? I've read that the up and down arrows are used to control the speed of the spindle. How is this practical and how do you know your spindle RPM? I need this explained as if it was being taught to a caveman who knows nothing about electricity (no mumbo jumbo). Thanks



Sorry joining the party at little late. If you are interested in a tachometer, www.littlemachineshop.com sells a "tachometer" for about $100. Pretty simple to install and wire. You just need to mount the "tach pickup head" somewhere on the machine to read spindle speed - you will probably need to fashion some sort of bracket to mount the head - the head is very small about 1/4" x 3/4" x 3/4" with 4 wires about 24" long. I have some adhesive reflective tape that came with a hand-held tach that I own. I just put a small square of the reflective tape onto the spindle, mounted the tach pickup to a small bracket and wired it up. Wiring is just attaching 4 color coded wires to the tach digital readout box and mounting the box in a convenient location and pluging the 120 volt transformer into the wall and into the tach digital readout box. I haven't done this to my Bridgeport mill (I have a 1942 M head BP with 6 v-belt pulley speeds adn 1/2HP 3 phase motor) but I have added a tach to both of my Altas lathes - I have a 6" atlas lathe with a variable speed motor setup and a 10" Atlas that I am planning on installing a variable speed setup on. Hope this info is helpful to you.


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## Mr. Kelly

I recently just did this for mine as well.  I threw a video up on Youtube to share how I did it.  Feel free to take a look.  Things can be done a lot simpler than I did, but I had specific ways that I wanted my machine to operate that required that I basically rewire the entire machine.  If you've got the variable speed already, I'd say just use that seeing as it's there and conveniently located at hand.  You would just need some basic switches connected to the VFD to start and stop the motor.  Depending on what you have for controls on your machine, you will probably be able to rewire them to use them with the VFD.  

Video:
https://www.youtube.com/watch?v=mKDn6rF6CKI&list=PL4PVAjiwV5Ko8WIFsihocXWmmupP56_yK&index=2

Good luck!
-kelly


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## NoShopSkills

Mr. Kelly said:


> I recently just did this for mine as well.  I threw a video up on Youtube to share how I did it.  Feel free to take a look.  Things can be done a lot simpler than I did, but I had specific ways that I wanted my machine to operate that required that I basically rewire the entire machine.  If you've got the variable speed already, I'd say just use that seeing as it's there and conveniently located at hand.  You would just need some basic switches connected to the VFD to start and stop the motor.  Depending on what you have for controls on your machine, you will probably be able to rewire them to use them with the VFD.
> 
> Video:
> https://www.youtube.com/watch?v=mKDn6rF6CKI&list=PL4PVAjiwV5Ko8WIFsihocXWmmupP56_yK&index=2
> 
> Good luck!
> -kelly



Hey Mr. Kelly, I'm the guy that was trying to get in touch with you via youtube.  What brand VFD did you use if I can ask.  I've already committed in this area and assume they are all fairly similar enough to be able to use similar remote controls in my planned installation?

With regard to the shielding of control wires, did you try it first with un-shileded connections?  Specifically how does the stop circuit cutout the power feed too?  Is your emergency stop button a STDP switch controlling two circuits (one for the VFD and another for the table feed) or is the power feed also somehow wired through your VFD's logic board? Thanks in advance and like I said over on the youtube side of this conversations, FANTASTIC!


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## Mr. Kelly

As this was a trial run for me and I had no idea at the time how the VFD would work for my situation, I decided to purchase one of the offshore chinese cheapies from Ebay.  I figured if I could give myself a proof of concept for a couple hundred bucks then I would be confident to spend a few extra bucks to buy a quality unit when/if my cheapie died.  It was a lot cheaper than another RPC.  

As far as functionality goes, they seem to all be pretty similar.  Some of the wiring and programming might be a little different.  The various manufacturers all have a variety of different models for different voltages and power ratings.  You will need to get one that will take a single phase power input and give you the 3 phase output in the correct voltage for your motor.  I also oversized the VFD for the power rating of the motor.

I had done a bunch of reading prior to setting things up and one of the problems that seemed to come up a lot was the propensity for VFDs to throw a LOT of interference.  Knowing that, I used shielded cables for all the control wiring.  Apparently the braided shielded wires are best, but I got foil shielded and it seems to be working fine.  I've got a computer a couple rooms away and didn't notice any weird stuff happening.  I have not tried a radio or near the machine while running myself, but have a residential tenant above that has not complained at all to me about it messing up anything of theirs, so I assume the shielding is doing it's job.

The wiring of the switches is a little more complicated.  Yes, the stop switch is an SPST switch, and is essentially controlling two separate ciruits.  That switch turns breaks a neutral that turns off a contactor (which is wired to the VFD and stops the vfd output) and cuts the neutral for the power feed control and stops that too.  That way the table stops when the spindle stops and the table won't feed until you reset the stop switch.

Hope that helps.

-kelly


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## rdhem2

The electrical noise they refer to is noise over the power wire from the drive back upstream to the panel then to all the panel circuits and the power company transformer.  Then off to the neighbors and ultimately the dam or steam plant or where ever you power comes from.  It can not be totally stopped but it can be controlled by using inline filters in the power wiring both into and out of the drive.  The shielded control wiring is to protect the drive from outside sources.  Like a ghost starting your mill up.  Not to protect outside sources from your drive.

The two pole contactor the previous poster refers to should be installed as the first item power enters coming into the control cabinet.  Two pole for single phase, three pole for three phase.

My 2hp Bridgeport is connected exactly as you wish to do I believe.  VFD is used for generation of a three phase supply of power, acceleration and deceleration of the drive motor.  Forward and reverse direction control. All speed control is via the Reeves Drive on the mill its self.  I have a digital tach but have never installed it as I trust what Bridgeport wrote on the dial to indicate speed.  I don't find exact speed control to be that beneficial or important.  Whether the spindle is going 950 or 1050 when you want 1000 is no big deal.  As long as it is close to 1000.

As for voltage, read your supply value.  Enter that value when programming the drive.  Same for amperage, cycles, service factor and other values.  Just enter what is on the motor nameplate.  No secrets there.

The pedestal of my mill has a door opening into the pedestal column.  I fabed a backplate and mounted the drive and terminal strip in there then fabed up a pushbutton box to mount my pushbuttons in and mounted it on an articulating arm under the DRO.  You have a good idea and I would not change a thing on mine.

If you drag a neutral wire in with the power wiring you can grab one leg of the power and use it to power your table drive, DRO, coolant pump, etc.  Guessing you will use a 240v, 20a branch circuit to feed the mill.  Be sure and tap this power ahead of the drive after the power relay.  I don't use this relay option, nothing wrong with the idea I guess I don't figure my VFD failing very often.

Good drive can be found for not a lot of money so you do not have to live with a rice burner.  And Hitachi is one of the best, but then it is Japanese.


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## NoShopSkills

Man you guys are a wealth of experience.  Thanks.

I'm traveling for work and can't play in the shop until Saturday, but my GS2-22P0 from Automation Direct has already arrived, sitting at home waiting to be installed.  I really don't anticipate any issues in hooking it up, but it's good to see how others have done so.  It's a 1 phase input model with a POT and defaults that match my application well.

As to the shielding and up-streaming, I'm not 100% convinced.  A long time ago I installed a car stereo system without good shielding.  The low wattage output audio run from the factory radio head to the trunk mounted amplifiers, was unfortunately routed alongside the power supply cable for the high draw amp.  _Induction interference_ resulted in the initial installation turning the new sound system into an audible tachometer!  At lower radio volumes, it was almost unbearable.  Once I re-ran the high amperage power cables a different route than the thin low amp audio cables, the problem went away. 

One problem I may have Saturday afternoon, is that the motor data plate is inline with the manually tensioned collet draw bar.  Over the years, sloppy wrench working, undoubtedly at the hands of elf like, chain smoking machine operators, has dinged up the data plate so badly that it's almost illegible.  The H.P. stamp was the worst.  I was not entirely sure what HP the motor was until I did some research on the machine and found the original factory motor choices were limited to two, 1.5 and 2.  Only that way was I able to eliminate a few of my guesses.  I'm 95% sure the Amp column is stamped 5.2.

While demoing the machine, the previous owner (short chain smoker) was unaware of the bare wires in the power feed cord that he draped across the mill table.  They shorted out of course and smoke emanated from the X axis power feed, which he insisted on continuing to prove that it worked.   It may be shot now and was discounted from the price.  Assuming it's toast, what's the best way to handle that?  Ebay discount axis feeds for a similar replacement? or look at stepper motors and consider marching towards a CNC retro fit with the ability to yield to program control?

Is there a discussion area more suited for older conversions to CNC?


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## NoShopSkills

Mine's now working.  Thanks mostly to Mr. Kelly's video!  Here's my video that may fill in some gaps.  Warning I like to ramble once I figure something out.

[video=youtube;FsN4w6l23xc]http://www.youtube.com/watch?v=FsN4w6l23xc[/video]


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## Mr. Kelly

Glad to hear you got it up and running.  I'm sure you'll have no trouble getting the controls set up.
-kelly


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## NoShopSkills

Progress!

https://www.youtube.com/watch?v=tcfqj2OmJGw


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