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

[noel shelley]

On noel shelley Said:

The pictures do not show the motor, is it mounted in the base?

There is an extraction hose in the photo. It is resting on the motor.

—

The advice to replace the motor is good in principle.

The machine is shown on the lathes.co.uk (https://www.lathes.co.uk/fritz-werner-special-millers/), described as size 0 (zero) and labelled 5.160W in the photograph. There is a full colour version, where the motor is clearly visible and which explains the hole in the rear left of your cabinet. There is also a photo with the side of the cabinet open showing the pulley on the motor.

You would do well to pull the machine forward, clean the back and motor and remove the motor.

You can then photograph the data plate of the motor, which will tell us a great deal.

Given the age and uncertain nature of the box of electrics on the wall, there is some possibility it is a phase converter. A bad (aged) capacitor in that could lead to the symptoms you describe. The motor might be fine – it could just be the feed to it that has gone bad.

Comments that follow are not supposed to sound negative, but more as factors to assess before turning the new motor principle above into action.

The challenges with a new motor will start when you see the old motor. How long is the shaft on the existing motor? What diameter is that shaft? How is the motor mounted (flange or foot)? If any of these result in an answer bordering on ‘unusual’, you have to assess the cost involved in fixing (rewinding) the old motor (assuming it is indeed faulty, and not the control box on the wall) against the cost, time and your ability to make a modern motor fit into the old one’s place.

Edit: there is a manual here: (https://www.scribd.com/document/725487535/FRITZ-WERNER-5-160s) which shows a three phase motor [it is number 27 on page 4 of the pdf if we are still having problems seeing it].

[robert bushillParticipant @robertbushill44287]

Hello Guys,

I have no idea what is going on with my machine, but I cleared some space today to take some better pictures and I thought I just try and start it, and it started up just fine !!!!!

The machine has been down for about 4 months and last week we had the Nation Grid outside my house as they had sent a letter out the week before saying we had low voltage in this street. I’d not tried to start the mill since they ‘fixed’ the voltage, but surly it couldn’t have been a low voltage issue that stopped my machine could it???

Anyway, I think it would be a very good idea to try and work out what I have as I am sure that information will be useful at some point. So here are few better pics 🙂

Thank you.

[Ian PParticipant @ianp]

I can offer no answer as to why your machine stopped working and then started working again but hopefully it will just carry on and be reliable.

What you appear to have is a VFD that operates on 240VAC mains and spits out three phase 415VAC. Whilst that model of VFD is no longer manufactured even a secondhand replacement will be in the high hundreds of pounds (£700 upwards).

Ian P

 

 

[DC31kParticipant @dc31k]

Manual for the Mitsubishi inverter here:

https://www.denfordata.com/bb/viewtopic.php?t=2437#p8779

Please download and save locally (like put it on a USB stick and leave in the control cabinert) so you have it as a reference should something go wrong in the future.

[noel shelleyParticipant @noelshelley55608]

Hi Robert, yes it is possible that the voltage drop on start up, along with the local low supply voltage could have caused may be a relay or contactor to drop out. Ah well, all’s well Etc.

An interesting arrangement that is Not now as it was built I think. Wired star at 415V with 220v control transformer down may be to 24v. It doesn’t show the speed, or power rating, strange. The 4th picture of inside the box has 2 relays with 24v coils and an RS mains to 24V power supply. The original wiring diagram might be interesting to see but I doubt it will tell you what you have now. This seems to be a Mitsubishi 240v input, 2.2Kw 3 Ph inverter (VFD ) and I guess the motor has been connected in Delta for 220v. If the cover over the terminal block is taken off it might be obvious which voltage is being used from the connections or you could just put a meter across the output terminal block in the inverter, though bear in mind it could be 415v, so be careful. The Mitsubishi manual for the inverter would be handy and explain the various circuits. Good luck Noel.

[Robert Atkinson 2Participant @robertatkinson2]

The problem was almost certainly caused by the low supply voltage. The inverter is, according to the manual kindly linked to by DC31k, is a 240V 3 phase input unit with a “permissive” lower voltage of 180V. It  has a low voltage protection function that stops it running if hte mains is low. See page 117 of manual
As virtually all VFDs / inverters just rectify and smooth the mains input a 3 phase unit will run on single phase but at lower maximum power. The combination of single phase input and low mains voltage would cause the inverter to not start the motor to protect it from excessive current (The inverter is a constant power device so will draw more current at low input voltage).

Robert.

[robert bushillParticipant @robertbushill44287]

Thank you very much guys.

So it may well have been the low voltage to the street that was fixed last week and nothing to do with my equipment, fingers crossed. I will take a pic of the motor with the cover off tomorrow, that may give another clue as to how the motor is wired? Considering the motor has run today, I think I can assume the motor is fine and I expect the VFD is also.

 

Thank you again for all your help.

[SillyOldDufferModerator @sillyoldduffer]

Late to comment on this, but I’ve been wondering if Robert and the forum have been jumping to conclusions.  The topic moved very quickly to ‘replace everything’, without bothering to do any diagnostics!  Maybe the motor and electronics are fine, and something simple is wrong.   Might have been low-voltage in the street, but if the fault recurs I suggest checking everything.

A few weeks ago I jumped to the conclusion that a poster’s description of a similar fault on his Chinese Mill meant that he had a faulty NVR switch.  Silly me, the description didn’t actually say what I thought – I read between the lines and made an incorrect assumption!   Fortunately Macolm was also on the case, and he suggested checking all the safety interlocks were working correctly.  He was right, one of the interlocks was out of adjustment, an easily fixed fault, costing nothing.  This might well be the case on this machine.  Intermittent faults are often due to loose connections, damaged wires, misaligned safety switches, and switches reaching end of life due to weakened springs or burnt contacts etc.   If the fault comes back, check everything – ask again.

Does anyone know of a company able to support machine owners like Robert who don’t understand electrics?    The firm he contacted probably stopped returning his calls because they didn’t want the work – from their point of view too risky.   When an unknown machine of this age with no manual stops working, investigation and repair is likely to be so expensive that the customer refuses to pay.  Cheaper to replace the machine rather than mend it.   This is particularly true of customers who bought a good second-hand machine cheap, without realising that having the beast repaired by someone else will be full-price!

Room I think for a repairer tuned into home-workshop needs, who could run through a quick diagnosis for a fixed price, and advise the best way forward.  The issue is what happens when his diagnosis is wrong! Who pays if a new motor is installed, and then it turns out that the electronics and electrics are sick too?   Doing uncertain repair work for money rather than on a voluntary basis soon gets expensive, potentially costing thousands rather than a few hundreds, liable to be a serious shock when the customer who thinks £10 is a fortune gets the bill!   Against that, a fairly high proportion of faults are simple…

Happy is the Model Engineer who understands machine tool mechanics and electrics well enough to do his own repairs.  But there are plenty of folk who want to get on with using tools and don’t have the time or skills needed to fix them.

Dave

[Author]

Posts