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To VFD or not to VFD, that is the question

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Forum topic by Heritage1 posted 03-14-2016 09:15 PM 1005 views 0 times favorited 14 replies Add to Favorites Watch
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Heritage1

7 posts in 263 days


03-14-2016 09:15 PM

Hello,

I’m new to the forum and have been recently reacquainted with a wood lathe. I acquired a variable speed General 260 with 2 motor options, a 1hp single phase 110/220 and a 1hp 220 3 phase motor. I have a single phase 110/220 input/3 phase output VFD, is there any advantage in using the VFD with this lathe? I know I already have speed adjustment, but would the VFD not allow me to run lathe at a slower speed… and if so, would this be ok for cooling etc…? Not sure if worthwhile, but thought I would ask for opinions. Thanks in advance.


14 replies so far

View Fred Hargis's profile

Fred Hargis

3926 posts in 1953 days


#1 posted 03-14-2016 09:29 PM

It will, mine is set up like that. Be aware, you lose torque as you adjust the frequency down. My lathe will start at zero at any belt placing; but it won’t have enough oomph to do anything until the freq gets close to maybe 45 hertz or so. So I still switch the belt around, but not as much. In your case you have everything you need to try, it wouldn’t be that hard to do and if you decide it isn’t all that good just undo it.

-- Our village hasn't lost it's idiot, he was elected to congress.

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MrUnix

4202 posts in 1658 days


#2 posted 03-14-2016 10:19 PM

What is in there now (if anything).. does it have a NEMA starter on it? Does the single phase motor have overload protection or does it rely on an external one in the starter? You will get a wider speed range with the VFD, and as long as you don’t reduce the speed too much, cooling should not be a problem and torque should be fine as long as you have a constant torque VFD like the FM50. HP will decrease as the speed decreases, but torque will remain constant (until you get down to below around 10% of rated, where it gets a little wonky):

The three phase motor is also more robust and more efficient, and you will get lots of extra benefits combined with the VFD. You can also get rid of the starter if you go the three phase route.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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Lee

49 posts in 337 days


#3 posted 03-14-2016 11:39 PM

I have a old Rockwell 46-450 lathe, very similar to your General 260 and I put a VFD on it. Much more versatile even with the Reeves drive. Plus I sometimes use reverse to sand difficult grain wood, cant do that without a VFD. So IMHO the VFD is the way to go.

-- Colombia Custom woodworking

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Heritage1

7 posts in 263 days


#4 posted 03-15-2016 01:18 AM

Thanks for the great feedback all, sounds like I will keep the 3 phase and use the VFD! I very much appreciate the advice and information you have provided.

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Heritage1

7 posts in 263 days


#5 posted 03-25-2016 04:12 PM

Ok, so I now have the components ready for install, I have my electrician on standby, however as an informative exercise I would like to get opinions on how best to wire everything. The lathe as mentioned above is a General 260 variable with a 3 phase 60 Hz 1 hp motor.

It is equipped with start/stop controls on front of lathe

and an electronic control box at the rear.

The VFD is a KB Electronics KBAC-24D Nema 4X analog VFD.


I will be setting it up initially to run off 110 until I move it down to my shop when complete where my electrician will run 220. These are the wires exiting the lathe.

Will I still require the electronic control once the VFD is installed or should the VFD take it’s place?

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Nubsnstubs

825 posts in 1189 days


#6 posted 03-26-2016 03:58 AM

You should be wired directly from the VFD to the motor. If you have a remote control, that’s even better…......

I ran my wires from the VFD to a receptacle in case I wanted to power another something with 3 phase requirements. If you can, don’t install the VFD on your lathe. Vibrations will cause it to fail earlier than if mounted on a wall with a lead with a 3 phase male plug from the motor. Also, after some time, slight vibrations will trip fault the VFD. Not too big a deal, but aggravating. ............. Jerry (in Tucson)

-- Jerry (in Tucson)

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MrUnix

4202 posts in 1658 days


#7 posted 03-26-2016 04:52 AM

You can rip out the existing starter, and the start/stop control station can be reused if desired, but will be redundant to the controls on the front of your ac drive, so you might want to get rid of it as well.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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Heritage1

7 posts in 263 days


#8 posted 03-26-2016 02:16 PM



You should be wired directly from the VFD to the motor. If you have a remote control, that s even better…......

I ran my wires from the VFD to a receptacle in case I wanted to power another something with 3 phase requirements. If you can, don t install the VFD on your lathe. Vibrations will cause it to fail earlier than if mounted on a wall with a lead with a 3 phase male plug from the motor. Also, after some time, slight vibrations will trip fault the VFD. Not too big a deal, but aggravating. ............. Jerry (in Tucson)

- Nubsnstubs

Ok, direct from VFD to motor, does that mean the VFD will take the place of the existing electronic control box?

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Heritage1

7 posts in 263 days


#9 posted 03-26-2016 02:18 PM


You can rip out the existing starter, and the start/stop control station can be reused if desired, but will be redundant to the controls on the front of your ac drive, so you might want to get rid of it as well.

Cheers,
Brad

- MrUnix


Brad,

By starter, are you referring to rear mounted electronic control?

View Nubsnstubs's profile

Nubsnstubs

825 posts in 1189 days


#10 posted 03-26-2016 02:53 PM

Mister Heritage, yes to your question. The motor doesn’t care where it’s power comes from as long as it’s the right power. The other controls mounted to your lathe are not needed, as the new VFD will supply the needed power to the motor. Disconnect and remove all the electrical stuff on your lathe, including the motor if it’s single phase. Install the 3 phase motor and new VFD. Wire the VFD according to directions. If wired correctly, it will work as expected. If the forward position of the switch runs in reverse, remove the motor cover plate OR cover plate on the VFD, and switch positions of 2 “Line” wires. That should have it running correctly according to the switch position. If you can get a remote control, get one and it can be put anywhere you choose if your cord length is sufficient. .............. Jerry (in Tucson)

-- Jerry (in Tucson)

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Heritage1

7 posts in 263 days


#11 posted 03-26-2016 03:05 PM


Mister Heritage, yes to your question. The motor doesn t care where it s power comes from as long as it s the right power. The other controls mounted to your lathe are not needed, as the new VFD will supply the needed power to the motor. Disconnect and remove all the electrical stuff on your lathe, including the motor if it s single phase. Install the 3 phase motor and new VFD. Wire the VFD according to directions. If wired correctly, it will work as expected. If the forward position of the switch runs in reverse, remove the motor cover plate OR cover plate on the VFD, and switch positions of 2 “Line” wires. That should have it running correctly according to the switch position. If you can get a remote control, get one and it can be put anywhere you choose if your cord length is sufficient. .............. Jerry (in Tucson)

- Nubsnstubs

Thank you, that is very helpful.

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MrUnix

4202 posts in 1658 days


#12 posted 03-26-2016 09:28 PM

By starter, are you referring to rear mounted electronic control?


- Heritage1

Yup.. but upon a closer look, it appears to just be a contactor and doesn’t have any overload protection like a normal starter. Same deal though, you don’t need it with a VFD (which will provide the overload protection in addition to controlling the motor), so you can yank it. Wiring for your machine is super easy. Hardest part will be figuring out where to mount the thing. Unless you plan on running a remote panel on it, you should find a good spot somewhere on the front of the lathe where you can access the speed dial. Then just run two wires (+ground) in from the wall outlet, and three wires (+ground) out to the motor.

Also, you won’t see any advantage by wiring it for 240v. At FLA, that setup would only require about 7A@120v, so any standard 120v outlet will be way more than enough to power it.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View Lee's profile (online now)

Lee

49 posts in 337 days


#13 posted 03-26-2016 10:35 PM

Well actually that starter does have overload protection, see the little red button on the bottom right, that’s the reset button, and just to the right is the amperage selector. But like you say the starter wont be necessary with a VFD. The only thing I can add to the discussion is IMHO you should keep the big red mushroom emergency stop button that’s on the front of the lathe, much easer to hit that, than the little stop button on the drive, You can wire that start/stop directly into the VFD very easily, the directions will be in the drive manual, Hope this helps.

-- Colombia Custom woodworking

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Heritage1

7 posts in 263 days


#14 posted 03-27-2016 05:11 PM

Thanks again all for your help, looking forward to setting it up.

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