VFD for my lathe

I have been looking into it also I have a 14" x 40" grizzly gunsmith lathe that I would like to convert. I have a grizzly mill with a vfd ,it is a pretty slick setup
 
SB............I have sold and installed many VFDs right up to 1000 hp, they are indeed the cat's a$$, however in your situation there is a lot more to it than just swapping the motor and adding a VFD. All your existing controls are set up single phase and almost assuredly use 2 pole contactors for forward and reverse on your motor. Unless you are well enough versed to rewire all your motor controls through your VFD (which can be done), you will need to change out the reversing contactors and the feed wires to the motor as well as your input line wires. There is a fair bit of wiring involved in reversing single phase motors and will be quite complex involving up to 4 different contactors or 3 with several auxiliary contacts. (This isn't really necessary but is often encountered for various reasons)
If you have been doing it all your adult life every day as I have it's a no brainer, but is usually beyond your regular local electrician. You will need some one with a good understanding of motors, VFDs and controls to make this conversion work. Once you do though, you will have infinite speed control in every speed setting and the better VFDs are all constant torque, so you do not lose your torque as you reduce your frequency. One word of caution that is usually only found in the very fine print if at all.......always try and keep your frequency in the upper half of the speed range (50% plus of nominal frequency) as you can and will run into motor heating problems at lower than 50% and 60% is better. These are almost always TEFC motors (totally enclosed fan cooled) and the air velocity over the stator is too reduced below 50% to effectively cool the motor. The other feature you should look for in a motor is called "inverter duty" which means they are specifically designed to be used with VFDs and have reduced eddy currents at lower frequencies and usually lower noise levels and increased cooling for use at reduced frequencies.
The VFD you have linked to is also 575 volt rated, no VFD can change voltages for you, it is volts in equal volts out. Some are advertised as doing this but you are just buying a transformer as a usually highly inflated price, that is incorporated into the system. They will be quite large and heavy and sometimes quite noisy. Beware the Chinese built ultra cheap VFDs they are absolute junk and a total waste of money. Stick to the better NA, Jap made or Euro ones with a track record and warranty.
If you really want to do this I would advise you look for a 3 phase lathe to start off with in 230/460 and then go with the VFD to accommodate your single phase power supply. This is a much better system to start off with and used 3 phase lathes generally sell for a lot less due to the limited industrial market.
This goes for any 3 phase equipment if you can get a super hot deal buy it and run it through a VFD...........but stay away from 575-600 volt equipment, usually very cheap on the market but double the price to VFD as you must use a transformer.
 
I only have 8 speeds on my lathe, optimal speed seems like it is always somewhere in between my options, with the VFD I could tune speed to whatever, If I could do this for 5-600 bucks I think it would be worth it.
 
Shouldn't be that big of a deal, your still feeding your controls with single phase as before. Your vfd will just supply your motor and will replace the forward/reversing contactors. It will run the motor forward or reverse...you just need an input or can usually control it locally from the front panel.
There may be a bit of control work to do but not much.
 
I just finished a swab cord retrieve using a GS1 from Automation direct.
Single phase input feeding a three phase .5HP motor.
All control is done by an internal 10VDC supply. Including direction reversal.
The options available are endless. You can download the manual from Automation Direct for free.
I buy a lot of equipment from AD, a lot of it is made in China. But AD does it right, they only sell
equipment with all North American approvals, doesn't make the equipment better, but at least you are protected if
something should happen.
.5 HP 3 phase motor C face $100
GS1 with fuse kit and brake sink $125
Pretty nice for the money.

BTW: you will have a steep learning curve if you are not familiar with VFD's. There are 40-50 parameters you can play with.
Shoot me a PM if you have any other questions or need pics.
 
Yes, I downloaded the manual. I have wired electric motors before but nothing like this. I work oilfield so next time I see an automation guy on location I will quiz them up, there are a few companies in my town that install electronics for oil site automation, will find out if they do this kind of stuff, some of the oilfield controls are very complicated, just not sure if they would do vfd stuff. For the most part this is way over my head. Pictures and a brief explanation in laymans terms would be great. I watched youtube vids all day on the subject yesterday and am convinced I need this :). I may hold off on my mill purchase now and find a used 3 phase one now, I steered away from 3 phase equipment but now that I am aware of these vfd sure gives a guy a lot more options for a home shop with only 220 single phase wiring!

My only concern would be the emergency stop on the lathe working, direction and speed could just be operated by the vfd, could I just wire the emergency stop switch to kill power to the vfd somehow? Also what would you recommend for a tach or RPM readout reading off a magnet on the back of the spindle?

I am working away from home for another week or so, will take a closer look at the wiring setup when I get home
 
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Any of the electricians in the oilfield should be familiar with VFDs, they are used in lots of applications around plants.
I just received a TECO phase converting VFD for my little mill, today is install day, I'll let you know how it goes down. It looks simple enough.
 
SkytopBrewster said:
Yes, I downloaded the manual. I have wired electric motors before but nothing like this. I work oilfield so next time I see an automation guy on location I will quiz them up, there are a few companies in my town that install electronics for oil site automation, will find out if they do this kind of stuff, some of the oilfield controls are very complicated, just not sure if they would do vfd stuff. For the most part this is way over my head. Pictures and a brief explanation in laymans terms would be great. I watched youtube vids all day on the subject yesterday and am convinced I need this :). I may hold off on my mill purchase now and find a used 3 phase one now, I steered away from 3 phase equipment but now that I am aware of these vfd sure gives a guy a lot more options for a home shop with only 220 single phase wiring!

My only concern would be the emergency stop on the lathe working, direction and speed could just be operated by the vfd, could I just wire the emergency stop switch to kill power to the vfd somehow? Also what would you recommend for a tach or RPM readout reading off a magnet on the back of the spindle?

I am working away from home for another week or so, will take a closer look at the wiring setup when I get home
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Keep in mind that standard 3 phase motors may not be "inverter duty". Standard fan cooled motors may overheat on a VFD.
See C-FBMI's post above........................
On the GS series VFD's, you have the option of displaying anything you want on the VFD.
You can display RPM if you want to, the display is not actual, but very close to it.
The rest of the controls should be done by someone with some experiance, some VFD's dont like motors powered down
on e-stop while operating, there are other ways to do it. Be carefull and be safe.

 
The e-stop should just be an input to the vfd....it will show examples in the manual typically on how to wire it. Have the display show hz. That way you can stay in the upper range. As has been said before, if the motor isn't vfd rated it may overheat if running at too low of frequency. With the speed options already on the lathe you shouldn't need to go too far above or below rated hz (60hz).
 
Buy an industrial brand name VFD for the simple reason that their technical support is far better than some ebay cheapies . There are a dizzying array of parameters in the setup menus that you really need to have the advice of the factory techs to get the most out of it

I have a Swedish Sorebro Bruk with 5 hp motor

Not only do I use the VFD as a phase converter , but I used it to replace the clunky old relays etc of the lathe

I have the control lever switch wired to the inputs of the VFD

On "forward or reverse" motor ramps up at controlled rate , but on off, it does dynamic braking into resistor then does DC injection at last 15hz so it stops after a couple revs ( my lathe does not have a mechanical brake )

I also wired Allen Bradly rotary selector . On direction cuts my lathe in half speed , which is nice when I want to hit the part with a file, countersink etc . The other direction is a momentary low hz bump . This essentially inches the motor forward a bit . Easier than pushing chuck to have gear box engage when changing speeds ( if necessary )

On my Mill, I have VFD set up to have preset rpm steps so its easy to play with speed on the fly by just bumping selector .

E Stop on mill does a hard DC brake as well . Turning it off does a more gentle dynamic brake so I don't have to wait for spindle to wind down

I have potentiometer on both Mill and Lathe to have fine tuning of rpm but I find its not really necessary

Bottom line is VFD is the cats ass for these applications ONLY if you take the time to learn and use the features . In order to do this , it helps to have good service guys to walk you over the programming.

The drive guy ( Yaskawa Motoman ) spent over 1 hrd walking me through , very patiently I might add programming drive while I was in front of it.

As far as "inverter drive motors " I wouldn't worry to much if you keep minimum running hz above 20Hz . Were std ( non Vector or VFD ) motors overheat ( since cooling fan is turning slower ) is when you are trying to inch it along at below 30% rated speed ( 20Hz / 60 Hz )

Its easier on motor to overspeed ( I generally don't run over 75Hz so 25% faster than nominal ) than below 20Hz . Lots of industrial installs run far higher overspeeds

Regarding your question about tach readout, you can have the drive display Hz , or whatever you want ( RPM of motor or whatever "scale" you desire ) so no need for external tach etc
 
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I certainly would not ignore the basic mechanical speed selection. It's not only a speed selection, it's a torque selection as well. The VFD drive would really be nice for the fine adjustment within the range. But first and foremost you want to select the gearing to suit the job so you get the right amount of torque.
 
Found an automation guy at work that's gonna hook er up for me. Ordered a G2 and a Marathon Black Max from Automation Direct $800 total and it sounds like a case of beer will get it hooked up by a pro! No more squeeling belts when I kick the lathe in high to 2000RPM!
 
SkytopBrewster said:
Found an automation guy at work that's gonna hook er up for me. Ordered a G2 and a Marathon Black Max from Automation Direct $800 total and it sounds like a case of beer will get it hooked up by a pro! No more squeeling belts when I kick the lathe in high to 2000RPM!
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Good for you !!
And that case of beer is a great investment, keep it safe!
 
Holy cow, you oil field guys are doing it all wrong!
Back East, we wait 'till garbage day, then pick up a tread mill at the end of your neighbours drive.
DC has very good speed control and easily reversible.
Enjoy the process!
 
Could a guy just leave the 220 going into the lathe (so the coolant pump, light etc work), take the wires that were going to the stock motor, run those to the vfd line in, then line out from vfd to the new motor? That way the foot pedal E-stop would still work if someone were to get wrapped up or something. Just use the forward/reverse on the vfd (the original start/stop/reverse lever would not work anymore right?
 
Like I said earlier, it is possible to run all your controls through your VFD if you know how........E-stop, forward-reverse, pedal stop, braking, etc, but what you are suggesting is a definite no, the way you are thinking about it is all wrong. All your safeties and controls must "talk" to your VFD, because it is controlling the motor, which makes everything move.......Yes you can run a separate feed bypassing your VFD for your pump and light. Your VFD must be considered as your primary control and all other controls as ancillary and must be run through the VFD.
Most VFDs will self destruct if you kill the power to them when under load....not every time nor all the time, but everyone I have installed has had huge warnings "DO NOT DISCONNECT POWER SUPPLY TO VFD WHILE UNDER LOAD" The VFD has certain shut down protocols and losing input power does not follow them. I must also disagree with the poster who said all is good regarding over heating at 20 Hz, this just is not true unless a special inverter duty motor has been purchased. They have different winding design and much larger displacement cooling fans and function flawlessly right down to full time 10 Hz, regular or even high efficiency motors will burn out from prolonged use below 30-40 Hz.
 
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c-fbmi said:
I must also disagree with the poster who said all is good regarding over heating at 20 Hz, this just is not true unless a special inverter duty motor has been purchased. They have different winding design and much larger displacement cooling fans and function flawlessly right down to full time 10 Hz, regular or even high efficiency motors will burn out from prolonged use below 30-40 Hz.
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Should have been more clear. We are talking about a motor on a lathe or mill , so you don't need a to worry about vector / inverter duty motor . Huge difference between the duty cycle on a manual machine tool and a motor running continuous on ventilation fan etc .

In addition , the application of a manual machine tool, the motor is seldom under anything close to rated load . Even when I am using my 5" carbide face mill, the motor isn't remotely hot

Lots of people with home machine shops use VFD for speed control and to operate 3 phase motors on single phase with no damage to motor

One of the other differences of VFD motors is high voltage insulation since VFD can cause much higher voltage spikes into the windings ( hence line reactors ) . This is not an issue on 230 volt input which home machinist have .

The most positively important thing to remember has been mentioned in post above. You should never shut down motor by removing power to VFD

Company I work for builds control panels for ventilation systems . We have to put huge tags on disconnect switches that tell you to turn off fan using "start stop switches" on panel not the disconnect .

Despite this, we change out ABB drives all the time because people can't read

so as already mentioned NO you don't want to wire the wires that were going to your motor to the input of the drive because that would kill power to your drive

Also you would not use the forward / reverse on your drive because it would not be convenient . Wire your original star / stop / reverse lever to the analog inputs of the drive
 
OP.........This winter while I was wintering in warmer climes my son who runs my companies when I'm not there, installed a single phase VFD on a single phase motor............I said BS but apparently it is now possible. I was trying to get all the ins and outs because I wanted to install one on my new 14 X 40 lathe. This would have very limited range of speed adjust because of the mechanical start switch in all capacitor start motors, but would work nicely from 40-75 Hz...............still looking into this new 1 ph - 1 ph VFD. Will keep you posted.
 
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