Is This Lathe Vfd Compatable

H

hothead

Registered
Registered
Joined
Jun 15, 2012
Messages
6
In about a month from now I will be ordering a Grizzly G0509G 16-40 lathe. it has a 3 phase 2 speed motor.
3hp-4hp. I would like to put a Vfd on as a 3 phase convertor.
I called Grizzly and they can't tell me anything about a VFD. All they say is they recommend a 15hp rotary convertor. I really don't want to have a 15hp motor running in my shop all day.

I am currently using an MSC Vextrax 13-40 lathe. it is single phase , Taiwan lathe. It is a very good machine, and will be keeping it also.
in the past I had a Grizzly 4003. per gunsmith lathe. ser#124. It also served me well. I chambered over 600 rifle barrels with that machine. I wish I still had that lathe. I don't know if they cheapened up the newer models , but I never had a problem with finish or vibration with that machine .

Got carried away from my question. Is the G0509G VFD or static convertor compatable.
HH
 
You can use a VFD to power this, but generally it will require re-wiring.

VFD should be hooked up with no switches in the 3 phase leads between the VFD and the motor. The G0509G as it is currently wired has the front panel controls using 120V power (from internal transformer) to control the KM1 and KM2 contractors (for fwd and rev) which supply 3 phase power to the motor. Most people when they do these conversions end up gutting the control panel, since most of the stuff in there will not be needed once you add a VFD.

Look at this thread for example of a complete retrofit, including gutting of the control cabinet:
http://www.hobby-machinist.com/threads/g4003g-going-3-ph-vfd.34549/

You can "abandon it in place" or partially gut some of the control cabinet (remove the KM1 and KM2 contractors), leaving the rest of it operational, and add three 120 V SPST relays (Fwd, Rev, Jog) which take the 120V power from the front panel and open and shut relay contacts which tell the VFD what to do. If you do this, it becomes a matter of hooking up a handful of wires... but you have to find a spot for the relays and the VFD to be mounted. Essentially the VFD would supply 3 phase power directly to the spindle motor speed selector (2 speed motor) switch, and the 120V which would otherwise tell the KM1 and KM2 contractors to control speed direction would instead tell the 120V relays to tell the VFD to run either forward or reverse. The advantage of this method is all the controls still work exactly the way they did before (estop, power button, spindle speed, brake).

One other "gotcha" is that the coolant pump on the G0590G is also 3 phase. This would either require a separate VFD or some crafty thinking to use the same VFD.

Here are some things to consider:
1. It is a major amount of work to do the rewiring; the rotary phase converter would require almost no work to set up.
2. The VFD provides you with some significant advantages, and is worth the work
- DC braking means you can set it up so the spindle comes to a complete stop in 1 second every time you secure power. This is a huge safety improvement.
- VFD gives you better control over spindle speed.
- JOG switch tells the VFD to spin the spindle at 5 Hz, rather then short duration at full speed (if that is what you want).
 
Last edited:
coolant pump will be no problem, as I have a high pressure single phase pump I will be using. the 1/8 hp pumps that are standard on most machines will not
pump dark cutting oil at enough pressure for chamber flush.
Dean , on this forum , I hope will be doing the electrical work for me on the VFD. I hope he chimes in and ask any questions necessary.
It would be really good to have a scamatic of what the finished control panel should look like.

\thanks hh
 
Hi HH

I am VFD-ing a GH1440 lathe at the moment, in the UK the power supply is 240v 1 ph or 440 3 ph ( 3, times 240v 1 ph to the motor)
A 1 speed 3 ph motor can be 240v or 440v, & can be run on a VFD,
but a 2 speed motor run on a VFD loses all its power & torque.

My lathe has a 2 speed motor 700/1400 RPM, 2.2 Kw
So I am going to buy a new motor, it will be a 1 speed motor 3 ph running at 959 RPM 2.2 Kw or 3 hp, price in the UK is £210 ($330 ? )

Most of the wiring will not get used, the limit switches & wiring will be used again.

This is my thread, hope it may give you some info.
http://www.hobby-machinist.com/threads/warco-enco-gh1440a-lathe.42723/

If you need any info just let me know, but i am still working my way though it myself.
 
jeff_g1137 said:
...but a 2 speed motor run on a VFD loses all its power & torque.
Click to expand...

Not really correct. The VFD doesn't care how many speeds the motor has. Two speed motor is just built with multiple arrangement of poles. If the nominal speeds are 1800 and 1200 rpm, then it has windings for 4 and 6 poles (this is in a 60 Hz world).

You can wire your VFD straight to one of the sets of windings, or go through the existing selector switch to allow you to select either speed range. Caveat: don't switch speeds unless the VFD is commanded to OFF.

EDIT: looking at your thread, the problem seems to be that you have a 440V motor and a 240V circuit. That doesn't apply to the OP; his machine is rated for 220V three phase.

At least the G0509G has a real schematic instead just the wiring cartoons like my G0709 manual. The funny thing is that the control box is almost identical to mine, same relay labels, same terminal numbers, etc.
 
Last edited:
Having been involved with two recent VFD builds involving 2 speed motors, I will through a word of caution into the discussion. Most lathe 2 speed motors in this class are usually 8P low speed and 4P high speed which usually works out to around 1800 RPM at 60Hz. An 8P motor will develop much greater torque then 4P, torque is usually constant over a range below the base speed of the motor, so something like 15-60Hz, and horsepower declines in a linear fashion. Above the base speed (60Hz), horsepower is constant and torque falls off somewhat linearly to about 1.5x base speed. The problem has been with both 2 speed installations, is that the motors did not run well on the 4P wiring. In one install, the VFD was set-up for both motor settings and auto-tune was loaded for each setting. So there would seem to be something about the high speed wiring that is not compatible with running it off of a VFD. Both machines ran well off of the 8P low speed setting, delta wiring configuration, where the high speed is a YY. There are different 2 speed wiring configurations depending on the motor, so it can also be run off of different voltages.

The end result, one machine stayed with just wiring to the 8P motor setting and spinning up the motor up to ~1.5 X the base speed. The other machine will get a new single speed 3Hp vector motor which we will spin up to 100Hz, and has a will have a very wide usable speed range. At least from my limited experience, I would either stick with the 8P setting on a 2 speed motor and loose some Hp, or replace the motor with an single speed inverter rated one and tweak the pulley/vfd parameters. The replacement motor will probably be more reliable and smoother then the stock Grizzly motor in these machines.

On VFD control system relays, I prefer to work with 24VAC or 24VDC low voltage systems, easy enough to use the stock transformer which has a 24VAC tap or add a DC power supply for the relays. I have issues trying to switch VFD terminal contacts with used contractors, probably because of arcing causing some resistance at the contact surface.

The G0509Ghas a mechanical brake, you can either switch to a VFD braking system using the electronic VFD brake and disconnecting the mechanical, or you can use the mechanical brake and send a free run commend to the VFD when the limit switch for the foot brake is engaged. Using both at the same time, they will probably fight each other, but electronic braking can be very quick. There are unusual circumstance where an electronic VFD brake may not engage.
 
Last edited:
I would not overlook the VFD on a lathe, it adds a tremendous amount of features and flexibility. A good RPC is also great starting point, you can also run the VFD off of the RPC, if added at a later point. There is a bit of a learning curve with the first VFD install, but subsequent builds go a lot quicker, and these forums can provide assistance with schematic designs, programming, parts, etc. You can always try the stock motor on either the 4P or 8P setting and see how it works. The type/brand/features of the VFD also factor into the compatibility issue. Alternatively, the stock motor could be replaced with a 3-5Hp vector rated motor, or a good VFD rated motor, the machine would run very smoothly. Vector motors allow full torque at 0 RPM and spin up to 2X their base speed, one does not need that range for a multispeed gearbox, but factory VFD equipped lathes usually have 2 mechanical speeds and the motor need to cover an 8-10 fold speed range. This 3Hp vector motor is a sweet deal and will be going into one of the machines, only wish I could fit one on my lathe. http://www.ebay.com/itm/LINCOLN-3-H...M-184TC-MODEL-AN-ANN4S3TC61Q15L-/191335088284 or a killer deal on a Marathon BlackMax 5Hp Vector motor http://www.ebay.com/itm/NEW-Maratho...-Volts-230-460-5HP-5400-RPM-NOB-/181894041914 . New vector/VFD motors do come up at way below wholesale pricing, but you do need to know what you are looking for, so you always have options over the stock motor.
 
Last edited:
tmarks11 said:
You can use a VFD to power this, but generally it will require re-wiring.

VFD should be hooked up with no switches in the 3 phase leads between the VFD and the motor. The G0509G as it is currently wired has the front panel controls using 120V power (from internal transformer) to control the KM1 and KM2 contractors (for fwd and rev) which supply 3 phase power to the motor. Most people when they do these conversions end up gutting the control panel, since most of the stuff in there will not be needed once you add a VFD.

Look at this thread for example of a complete retrofit, including gutting of the control cabinet:
http://www.hobby-machinist.com/threads/g4003g-going-3-ph-vfd.34549/

You can "abandon it in place" or partially gut some of the control cabinet (remove the KM1 and KM2 contractors), leaving the rest of it operational, and add three 120 V SPST relays (Fwd, Rev, Jog) which take the 120V power from the front panel and open and shut relay contacts which tell the VFD what to do. If you do this, it becomes a matter of hooking up a handful of wires... but you have to find a spot for the relays and the VFD to be mounted. Essentially the VFD would supply 3 phase power directly to the spindle motor speed selector (2 speed motor) switch, and the 120V which would otherwise tell the KM1 and KM2 contractors to control speed direction would instead tell the 120V relays to tell the VFD to run either forward or reverse. The advantage of this method is all the controls still work exactly the way they did before (estop, power button, spindle speed, brake).

One other "gotcha" is that the coolant pump on the G0590G is also 3 phase. This would either require a separate VFD or some crafty thinking to use the same VFD.

Here are some things to consider:
1. It is a major amount of work to do the rewiring; the rotary phase converter would require almost no work to set up.
2. The VFD provides you with some significant advantages, and is worth the work
- DC braking means you can set it up so the spindle comes to a complete stop in 1 second every time you secure power. This is a huge safety improvement.
- VFD gives you better control over spindle speed.
- JOG switch tells the VFD to spin the spindle at 5 Hz, rather then short duration at full speed (if that is what you want).
Click to expand...

If I understand your approach, you are using 2 isolating relays to control the VFD inputs and retaining the existing motor reversing contactors. If this is the case you merely need to disconnect the 3 phase wires from these contactors & connect the VFD directly to the motor. The advantages to this approach are: 1) maintaining all of the existing safety features (E-stop, braking stop etc.) 2) Ease of wiring. #3) The lathe can be readily returned to it's factory-wired condition should you sell it in future. This is the approach that I am currently installing to power my vintage Harrison M300 13 X 40 lathe.
 
You must log in or register to reply here.
Back
Top