New motor/esc for mill?

[robert bushillParticipant @robertbushill44287]

Hello,

I have had my old German Horizontal/vertical combo milling machine now for about 15 years and it has been perfect. But the other month I turned it on, it spooled up and then spooled down within 10 seconds. Since then it has been dead.

The mill has a large three phase motor and two ginormous boxes full of electronics that I do not understand. My guess is something in one of the electronic boxes has failed (or tripped). However, I would also guess it would be cheaper to roll the dice and buy a new inverter or a whole new single phase motor/esc combo rather than pay somebody to come out and tell me they can’t fix it or do not understand it?

The mill is a typical medium sized home workshop type machine in cast iron standing about 5tft tall with an 2ft long bed.

Please could somebody advise me on what direction to go, new 3 phase inverter for my old motor (assuming my one is dead) or a new single phase motor/esc combo deal. I don’t mind swapping over the motor for a single phase and all the messing about that entails if that is the best way to go, but I would need to know what HP motor would be best for a machine of this size.

I have tried to talk to ACDC Drivers UK, but once I showed them the pictures of the mill, they stopped talking to me and have refused to communicate since! So other sales outlets would be better for me.

Many thanks for any help you could give.

Rob.

[bernard towersParticipant @bernardtowers37738]

Take the old motor off and get it checked out for starters then if ok dump the old electrics and buy a new inverter. that should give you the time to clean the old girl up a bit!!!. I did that with my grinder and now I have just two wires under the machine magic.

[not done it yetParticipant @notdoneityet]

I would just do the rudimentary checks on the motor. Stator resistance phase-to-phase and to earth.  Then I would buy a suitable single phase to 3 phase (at 220V) inverter and check if the motor works correctly.  Then (or any time) check the motor voltage and whether it is wired star or delta (if 415V only), dual voltage (415/220V)

Reconnect in delta, if star@ 415V, or see if the star point can be easily separated and rewired, from there, in delta configuration.

If the motor was not able to be converted to 220V three phase, I would source a suitable second hand motor that is able to be wired delta 220V and use that and the inverter as the machine drive.

[Ian HewsonParticipant @ianhewson99641]

Seeing the old Fritz Werner, took me back to 1959 in the apprentice training workshop where one of the first machine I saw was a large vertical mill. As electrical apprentices from YEB we never got to use it, but it still sticks in my memory,

Suspect it was second world was reparations from Germany.

Ian

[John HaineParticipant @johnhaine32865]

ESC = VFD I assume.

[robert bushillParticipant @robertbushill44287]

Yes, VDF.

I don’t know anything about the electronics, I just mash up the metal in the machine 🙂

[noel shelleyParticipant @noelshelley55608]

Looks like a Centec 2B copy with the Mk3 head, about 1Hp. Is it variable speed ? Is it 220v or 415v 3Ph. There may be someone near you who could help, where are you ? Check the voltage, then the resistance phase to phase and phase to earth, ideally with an insulation tester at 5oov, otherwise with a multimeter. If this is good then the motor looks sound. The box on the wall ? what is it, old VFD or a static converter ? If a 220V VFD then get one to suit the motor power. 415v VFDs are available but more costly. Or change the motor for a single Phase 1450 rpm 4 pole motor, simple and little to go wrong for a while. Good Luck. Noel.

[robert bushillParticipant @robertbushill44287]

Hello Noel,

It runs off the 240v mains, but then through two huge boxes of stuff, I think the motor is 3 phase, but other than that, I have no idea. I do not understand any of what you have suggested and wouldn’t know where to start. It would be very dangerous for me to even start to poke about with my DVM and try and fix it. I live in South Wales, not far from Cardiff.

Thanks.

[not done it yetParticipant @notdoneityet]

The one singular recommendation I would not encourage, support or advocate is fitting of a single phase motor.  The advantages of a speed regulatable, programmable, more reliable, probably easier to install and an easier-to-use machine for the hobbyist.

lathesdotco indicate the motor is likely 2.1HP (~1.5kW).

 

My lathe, both mills and the surface grinder are all run with 220V VFDs.  My bandsaw and (cheap and nasty) pillar drill are the only bench machine tools with single phase motors.

[RobCoxParticipant @robcox]

In your position I’d cut your losses and get a new 3ph motor and a suitable VFD. The old electronics might be “authentic” but if capacitors have died and/or the motor has a dodgy winding and you have no means of safely determining what is wrong, completely new electrics is the easiest way to go.

With a modern VFD it is relatively simple to control it from remotely mounted switches and a potentiometer to obtain start/stop, fwd/rev, em stop and speed control. I have mine located on a pendant at a convenient height to save my back!

I’m too far away to be able to offer to pop round and help, but if remote advice is useful, I’m willing to help.

Rob

[RobCox]

On RobCox Said:

In your position I’d cut your losses and get a new 3ph motor and a suitable VFD. […]

Absolutely spot-on, Rob !!

MichaelG.

[DiogenesParticipant @diogenes]

..er, thermal cut-out? fuse? ..what’s on the wall, static invertor and starter?

[noel shelleyParticipant @noelshelley55608]

Hi Robert, The pictures do not show the motor, is it mounted in the base ? a picture will give clues as to what it is, ideally of the data plate. In changing the motor one has to find a new motor to fit the space, or make up new mounting plates Etc. and be able to align the pulley/belts. The vogue for changing a motor to VFD is not always as simple as one might hope ! You have not told us if your old unit has variable speed, though you talk of an ESC, you mention 2 huge boxes, it could be a static converter, or possibly a rotary converter. From what you have said, I would take the motor out and take it to may be a rewind specialist for testing, this will dictate your next move. If the motor is good then you will know what voltage Etc and a new VFD/ESC can be got. If dead then depending on its size Etc you know what your looking for, or if it’s an odd ball then rewinding can be an option and if it was Star wound this can be changed to Delta on rewind. Now Delta a new VFD is easy. The rewinder will be able to offer advice. I’m on the Norfolk coast or I could sort this for you. Good luck. Noel.

[robert bushillParticipant @robertbushill44287]

Thank you guys for all your help, it is greatly appreciated.

I will dust the old girl off and take some much better pictures, then maybe we’ll be able to at least have an idea of what I may have? Up until now, I’ve just turned her on and used her. This whole situation could just be a trip or a fuse (not the 240v plug fuse, I checked that!), but not knowing what I’m looking at, I don’t know.

Once what I have is ‘known’? I can make my next move of finding somebody to look at the motor and see if it works? If I have to replace the motor and make new mounts, that is not a problem. It’s only the electrics I am clueless about, all the practical stuff I’m good with 🙂

Thanks again,

Rob.

[noel shelleyParticipant @noelshelley55608]

One thought is to join one of the local Model Engineering Clubs near you, there is likely to be some one who could help you. Good Luck. Noel.

[DMRParticipant @dmr]

As Noel says,

Join a club or give a clue as where you are and someone may come to your aid. There are too many variable possibilities to help you if you don’t know electronics and 3 phase is particularly dangerous.

Dennis

[noel shelleyParticipant @noelshelley55608]

He’s in Cardiff Dennis. If he was a bit closer I would go out and set the ball rolling. Noel

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