VFD on a PM 1340 GT help for dummy

[Latz55]

New to the forum and read most of the posts for using a VFD on a PM lathe. Most seem to utilize the many of the features of the VFD that I am not interested in. I just want to use the existing controls already on the lathe. I'm having a hard time following but understand that the VFD should be connected directly to the motor rather than the control panel. I need to come up with the easiest method to provide power to the lathe using the existing lathe controls without adding any other remote features. Is there a way to directly tie the three wires to the R-S &T terminals in the control box by programing the VFD as strictly a power supply (similar to wiring a 3 phase building electrical service or a RPC)? I understand that it may be possible to use the VFD in a fixed 60Hz and in a V/Hz mode and run the three wires and ground directly into the control panel. I have a PM 1340 GT lathe with a 2 hp 3 phase motor and using an Automation Direct DURApulse GS 20 series GS21-22 PO VFD. Any help would be greatly appreciated.
Thanks - Rick

 

[jwmelvin]

No don’t try to use the VFD as a provider of 3-phase power that may be switched on and off to the motor.

Take the time to figure out how to wire the lathe controls as low-voltage controls for the VFD. The VFD will be connected directly to the motor.

 

[mksj]

You strip out the high voltage wiring to the F/R contactors and just use a set of terminals to trigger the low voltage VFD inputs. The motor is directly wired to the VFD, This is all outlined in these documents at the end of this thread in post 89. The GS21 has different programming parameters and the inputs would be different so would need to be adapted. You can make the changes in the control board wiring and hook it up in about 1-2 hours. Let me know if there is something you do not follow. I would add a speed pot, it is a simple thing to do and you can also flip the motor pulley and use the large motor pulley to large headstock pulley to make it a single speed and then use the VFD in the 30-90 Hz range.

Pm1340gt Lathe Basic Vfd Control Conversion Using The Stock Control Board And Switches

Not really and issue since the resistor's I recommend are completely sealed and the wiring is embedded. You could also mount it on the inside of the VFD cabinet which I have seen done. It does not get warm so heat is not an issue. My original 1340GT VFD with the WJ200 had it in the headstock...

www.hobby-machinist.com

 

[Ken226]

There's no way to get away with just wiring the VFDs motor terminals to the 3 phase motor, and still getting the stock controls to work. The motor would work, but only respond to commands from the VFD keypad.

To use the stock controls, you will have to wire the VFDs external control terminals through the lathe's controls/contactors.

I just did this. Actually in the final stages of buttoning everything up.

There's no "dummy" way to do this. But if your willing to put the time and effort into learning, it's pretty easy.

I used the method @mksj layed out above. Except, my Birmingham lathe was a little different, with a 120v transformer and all 120v ac contactors.


I was a little worried that my contactors might not pass the low volt signal for the VFD controls. My lathe is 20 years old, and those the contactors have been passing current directly to a 2hp single phase motor that whole time.

i was pleasantly surprised when it worked perfectly, the first try.

 

[BladesIIB]

mksj gave you the lathe specific details above. He is truly an expert in this and has helped many of us get our machines set up with a VFD. I put this video together to summarize what I learned from Mark (mksj). It may help with the high level what and why and help you follow the details Mark sent you.

 

[cday2021]

New to the forum and read most of the posts for using a VFD on a PM lathe. Most seem to utilize the many of the features of the VFD that I am not interested in. I just want to use the existing controls already on the lathe. I'm having a hard time following but understand that the VFD should be connected directly to the motor rather than the control panel. I need to come up with the easiest method to provide power to the lathe using the existing lathe controls without adding any other remote features. Is there a way to directly tie the three wires to the R-S &T terminals in the control box by programing the VFD as strictly a power supply (similar to wiring a 3 phase building electrical service or a RPC)? I understand that it may be possible to use the VFD in a fixed 60Hz and in a V/Hz mode and run the three wires and ground directly into the control panel. I have a PM 1340 GT lathe with a 2 hp 3 phase motor and using an Automation Direct DURApulse GS 20 series GS21-22 PO VFD. Any help would be greatly appreciated.
Thanks - Rick

When I ordered my PM-1340GT it was a toss up for me between single phase or 3 phase. I opted for 3 phase because I could get the machine sooner and thought, "hey, how hard can wiring a VFD be?" My initial idea was just like yours -- whatever I needed to do so I could use the stock controls and simply turn single phase power from my house into 3 phase to drive the system I was getting. After I placed my order I asked PM about the VFD and how to proceed. They forwarded me an older copy of Mark Jacobs' documentation on wiring the system up with a VFD. Although it took a while to wrap my head around all of the options and the wiring to make sure I was doing things properly and safely, I ultimately added in the speed control, 2 stage braking, and jog joystick in Mark's designs. I assume you do not know who Mark is. He's the mksj guy up above that responded to you.

After having started with your ideas of simply getting 3 phase power to the lathe to get it up and running and instead switched gears to follow Mark's documents... boy, I am super glad I did. I have a few other shop tools (drill press. 2x72 grinder and mill) that are VFD controlled so I was very hip to the "turn a knob" speed control you get with a VFD. I really can't imagine my 1340GT without speed control now. I'm extremely happy I took the VFD route and that Mark has so graciously released his schematics so others can do the same. Likewise for the braking and jog function. I don't use the jog that much, but I'm stillv very new to using a lathe. The speed control and braking are both worth the conversion alone. If you also add in the proximity stop system Mark has developed... you'll be sittin' pretty and likley be very pleased with your system.

If you go the VFD route I'd recommend having Mark do your system.

 

[hanermo2]

Somewhat agree with everyone else ..

Was very very happy with my lathe 1.5 kW industrial AC (EU, 220V single phase) motor and belt drive for 8+ years.
Had VFD on my Bridgeport M Head and thought it was excellent.

Then built a good rigid industrial timing belt drive for the lathe spindle, HTD-8, 30 mm wide.
1:3 transmission, 24 : 72 teeth with industrial tapered bushings.
With a goal of a C axis for milling, cnc.
And a 2.5 kW industrial AC brushless servo, 10 Nm cont, 30 Nm peak.

So 90 Nm peak torque upto 3 secs.

The end result is absolutely unbelievably good --
because of the absolutely constant steady torque and feed,
absolutely perfect surface finish,
10x the effective torque EVER before in high-load situations at low rpm,
From 1 rpm to 1000 rpm.

So I have used 25 and 30 mm drills in tool steels, 50 mm deep, using 2-4 kW of absorbed power, with excellent results.
About 3x faster than the old system, and with no belt changes, and no backgear.

And an ISO BT30 face mill, 50 mm wide, cutting 4 mm deep into a tool steel block at 600-700 rpm, medium high feed, fantastic finish.
About 7x faster than ever before.

The AC servo is vastly better than I ever expected, and mostly due to the torque.
Which I did not expect to be important at all.

And also because when it stalls, the machine stops, and nothing breaks.
The error count reaches a certain number, around 0.02 mm in positional error, and everything stops no-muss, without breaking tools, mounts or drive axel bearings (built very strong, industrial).
Even very thick/big workpieces and tools easily bend over 0.02 mm (to 0.1 mm, maybe 0.2 mm) before breaking or breaking their holders or mounts.
I´ve stalled the spindle drive maybe 4 times, and this is no problem.
Overloading it, effectively using 7.5 kW of power or more for 3 secs or more.

A modern good VFD is functionally and electrically very close to an ac brushless servo.
They both have about the same parameters in terms of pid tuning, and do ramped acc/dcc and reverses and adjustable speeds etc.

Anecdote..
A 2.5 kW AC brushless servo, here in europe, 220V household current,
will accelerate to 3000 rpm in about 10-20 ms, or 0.02 s.
No load.

A VFD accelerates a 3 kW motor in about (0.5)-2 secs.
It could do better, but would typically overheat or overload, say if run 1000 times continually fwd/rev at max acceleration.

The servo reacts about 100x faster than a std motor/vfd and updates the reaction parameters at typically 12 kHz or 0.0008 secs.

 

[hanermo2]

Further to the thread..
I put a 3 HP 3-phase motor on the new-running VMC due to economics.
Had the Hitachi 2.2 kW VFD, the new motor was 150€ shipped in Spain.

A new ac servo of 2.2 kW +/- is about 900€, BUT

I will then also need a controller able to get step/dir to it at a good rate to get angular real-time positioning out of it.
For broaching and reverse broaching and rigid tapping/threading,
around 10.000 counts/turn at encoder as a minimum.
A new cslabs setup is about 1800€ all-in.

So total cost is about 2700€ minimum.
And more importantly about 300 hours of work time to get everything done, at 200€ each.

So I got a very good VFD system with great torque (gearing, 1.4 iirc x 2 x 5 x 15 mm HTD belts, aka double belts).
With a bit oversize motor of 2.2 kW, 220V AC.

The VFD+3-phase motor only cost me 150€ now, as I had all the other parts already.
Including pulleys and belts.
Once everything is finished, I will go to the proper solution and an AC servo.
Perhaps a high speed servo in the 5000 rpm range.

But for now it runs, very well.
For not much additional investment, and a working industrial quality setup able to run long hours.

 

[Rodneyk]

I have just finished installing the package that Mark Jacobs produced. He is definitely the expert in these forums, and he is an incredibly helpful when it comes to getting people going down the right path. I did not realize what I was getting into when I bought a 3 phase lathe, and without Mark I would be lost and probabaly making a sub par tool. Now since I have installed the system I could duplicate the work, BUT I would still pay Mark to help build it for a couple of reasons. 1) He knows how to source quality parts. 2) He knows which parts are needed. 3) His workmanship is excellent. 4) His prices are way too low for what he is providing. Oh sure when he first gave me the quote I choked a bit and almost tried to do it myself. But in hindsight I am VERY glad that I went forward with Mark. It was well worth the money.

Now with the documents he posted above you could definitely create the system yourself. And he will probabaly still answer questions for you since the answers benefit other.

 

[Winegrower]

Most seem to utilize the many of the features of the VFD that I am not interested in. I just want to use the existing controls already on the lathe.

Just to make sure all options are clear to readers of this thread, I believe the simplest way to get started is to get a $150 phase converter and wire up the obvious way, 220V single phase on the line, 3 phase to the lathe. You use all the features that the manufacturer provides, just as folks have used successfully for many years.

Some will say you only get 2/3 power. I just note that the Takisawa is a good heavy duty lathe, and even taking big cuts in steel that throw blue hot chips all over, I have never come close to it even slightly slowing down.