Tos FN22 milling machine (Deckel clone)

[Pete.]

If it is shot Pete, I can give you the contact details of my pal Dave, who could rewind it to do backflips if you so wanted.

He is £45 an hour though so you'd have to weigh up the costs,

Cheers Brad something to think about but I really think if it does go pop it'll be a new unit. It's a bit silly even trying it but then they said I'd blow up my DC drive by switching the motor on and off with the run enabled but that was about 7 years ago and the spare drive is still gathering dust

 

[roofman]

I got the multimeter out today and did some checks to make sure I had all of the wires and windings labelled correctly and it was a good job I did because I found that two of the windings were reversed compared to what the schematic said they should be, inside the motor terminal box. Perhaps it was someone's clumsy fiddling that caused one of the tails to short and go open circuit, or perhaps it was just 'done that way' and the tech adjusted the wiring to compensate, or maybe someone just didn't like which way they had to turn the fwd/reverse lever. Whatever, my job was to find out what was wrong.

So I checked the switch connection sketch I made, transferred the labels from the switch and from the terminal block onto the schematic and I already had the windings labelled from when I stripped the motor. This all gave me the info I needed to cut and join the connections how I wanted. However, when I did my checks, I found that U-X had a resistance of 9ohms whereas Z-V and Y-W had 6 ohms each. Clearly something was labelled wrong so I double-checked the schematic and that was all ok up to the motor terminals, they must have two of the connections reversed internally. I knew it had to be the two 6 ohm ones that were backwards because you can't have ONE thing wrong, two must be swapped.

View attachment 331253

At first I thought it was Y and Z that were backwards but then I realised it couldn't be those two because they X, Y and Z are brought together in a star point for high speed so if they were swapped over the motor would turn one way in FWD low and the other way in FWD high. It must be V and W. I re-labelled these and the my readings then all made sense at 9 ohms each.

So first I checked (as above) that the U,V,W points were properly opposite the X,Y,Z points - check
Then I had to double-check that they were opposite, and also in the same sequence as the schematic, important to get straight in my head before I started cutting wires. To do this I split the connection at W and then took sequential readings all around the loop. They all tallied up at about 5.2ohms per winding. I also checked visually which direction the wires were running and found that all of them were going in the same 'sense' for all three phases.

After that I labelled the split at W as Wx and Wy, check with a multimeter, split V and labelled them as Vx and Vz, then split U and lebelled them as Uy and Uz.

View attachment 331243

To complete the job I have to take each of these six split points and reconnect them to the corner that they are pointing towards. So Wy will connect to X and Wx will connect to Y which will put those two windings in parallel, and then do the other four the same so that I can use the motor with a 240V VFD.

Here is it right now all labelled up ready to go.

View attachment 331256

Now, I do realise that this might all be in vain. I might have damaged the enamel on the windings and cause a short, but it looks pretty good right now (I've done a bit of motor rewinding in my teens) or the VFD might cause the aged windings to break down, or any number of things might go wrong but the way I see it if the motor was going for scrap anyway I don't see that there's much to lose except a few quid and half a day's time that I would have spent making mounting adapters anyway. I've got some fresh air-drying enamel coming and I'm going to order more binding so I will carefully coat all the bits I've worked on then cook it gently to dry the coating, bind it up then coat it again to give it the best chance. If it goes pop, I'll buy a new motor.

Wow!! i envy your knowledge mate

 

[Pete.]

Okay so this week I have grabbed various spare moments to look at re-configuring the windings on this motor.

Just to re-cap the windings were connected in low-speed (4 pole, 415v delta) mode and I needed to re-connect them to work on 230v 3 phase which meant splitting the two windings and taking ends of the coils that are split and connecting that end with the opposite end of it's partner coil, effectively putting them in parallel. Putting two identical resistors in parallel halves the resistance so if you feed them with (about) half the voltage they will draw double the current and consume the same power.

I'd already split the windings and confirmed the orientation so I set about adding in tails, sheathing them with heat-proof sleeving and bringing the six loose winding ends together in pairs to the three corner phase connections. I temporarily secured them all in place and then covered the three input legs in a couple of layers of shrink sleeving.

Turned out I had jumped the gun a bit there because when I went to measure the resistance between the three phases they were 1. Not what they were supposed to be and 2. Not all the same.

So there's some basic formula for motor windings, which are essentially low-value resistors.
From my earlier measurements I knew that one winding was 5.18 ohms.
Putting two in parallel (my goal here) should halve the resistance which should make 2.59 Ohms.
Joining the three parallel pairs in a delta configuration should result in any two input legs reading 2/3 of one coil's resistance = 1.73 ohms or thereabouts (acutally slightly more because of the resistance of the tail wires).

I was getting about 2.3 ohms on two readings and 2.8 ohms on the third.

So I stripped it all down again and lo and behold I had a bad joint on one of the original connections. A dab of solder on that joint and re-connect all the windings (this time without bothering to insulate and tie them) and I was getting 1.8 ohms on all three input wires. Happy days. I then went around carefully and re-did ALL of the joints including the originals so that I could be sure that I never had any more problems, fingers crossed.

After I had confirmed the connections were all good I got my cotton binding and tied the lot together, grought the three tails out to the junction box, added some heavy sleeving where the original feed wire had shorted on the casing and then gave the whole lot two really good coats of winding varnish from Brocotts. It's been air derying for a couple of days now so should be good to go back together tomorrow.

I've checked the resistance and all of the windings are showing an even 1.8 ohms and nothing to the casing. I don't have a megger to test it so I'm just going to leave that bit to luck.

 

[dobbslc]

Bloody magic!

 

[Maker]

I'll have to get myself some of that winding varnish, last one I did I used heat shrink and tie wraps, and I'm pretty sure the one on my drill is tied down with butcher's string.

 

[My Old Landy]

I'll have to get myself some of that winding varnish, last one I did I used heat shrink and tie wraps, pretty sure the one on my drill is tied down with butcher's string.

View attachment 332142

You have posted that before as I used it as inspiration and did my Raglan motor in the same fashion

 

[Parm]

Simply astounding attention to detail and a brilliant and informative write up

 

[Pete.]

Well, the motor is built and hooked up to the VFD and it's running great. However, this has not been a success. It's gone wrong in a way I never would have expected:

At 50hz the motor is running at exactly half speed. I've checked the parameters and they seem to be pretty spot-on so the only thing I can think of is that hooking the windings up in parallel has converted this 4-pole motor into an 8-pole motor. either that or something else is going on which is completely beyond my ken.

I've now reached not only the end of my knowledge but also the end of my resolve with this so the motor is going for scrap and I'm fitting a new one. As a matter of fact I'm giving serious consideration to pulling the very nice NOS Siemens motor from my HLV and fit that and the new WEG vfd into my mill. I can then fit one of my two spare 1.5KW vfd's into the Hardinge and get a 2HP motor for it which is still bigger than the original so it won't suffer a lack of power. I#ll give all that some more thought over the weekend.

 

[Pete.]

Dude let me take it round to Dave

Not yet kimosabi

Well, what a rollercoaster ride this thing is taking me on I'm glad I didn't give up on it. Turns out there's nothing (obvious, yet) wrong with the motor at all it was the Altivar ATV12 inverter I had it hooked to. Either it's faulty or (more likely) there's a parameter buried in the 130-page manual that I haven't understood but I hooked a different, known good motor to the drive and that also turned at half speed.

Hooked the motor up to an el-cheapo Chinese drive that someone linked to on Amazon and it's doing exactly what it should





Now this inverter is very basic there's no facility to input the motor parameters and no auto-tune but it IS simple to configure and makes the motor go round and round, if a little noisy. I won't be using it anyway because it's only rated for 1.5KW, okay for testing on the bench but no good to run the machine.

 

[Martin-Sy]

Well I'm perplexed. The display said 50Hz so cannot see why it's 1/2 speed unless 8 pole.
Anyway that's great news and you'd have been mighty p'd off if you'd bought a new motor and that only went at 740rpm!

 

[daleyd]

The vfd is probably set to 8 pole

That would only affect the speed (rpm) reading - the hz would be the same no matter what motor pole. I’ll have a look through the software and see if there’s anything obvious.

I’ve used stacks of these and can’t recall having a similar issue.

 

[Pete.]

Thanks Dale.

I can't even find a parameter to set the pole count and doing a erch through the PDF for the word 'pole' yields zero results :/

 

[daleyd]

Thanks Dale.

I can't even find a parameter to set the pole count and doing a erch through the PDF for the word 'pole' yields zero results :/

No probs - I think It’s called Spd or something(??) - I’m not in front of pc at mo but will have a scout through a bit later. Even if you don’t use the software I find it useful to go through as stuff is grouped logically.

If you have a usb - rs485 converter I can send you a pin out for a chopped up Ethernet cable to connect. The software (so move) is free, or at least was…I can send you the file if not.

 

[Pete.]

I've got a FDTI thingy somewhere I'll have a look for it see what exactly it is.

 

[Martin-Sy]

Have you tried resetting to 'factory defaults' ?
From the manual it looks better than the Siemens ones I put in my CVA, but no 3kW 230V version alas.

 

[Pete.]

Have you tried resetting to 'factory defaults' ?
From the manual it looks better than the Siemens ones I put in my CVA, but no 3kW 230V version alas.

Yeah I did that last night.

 

[Martin-Sy]

Vector mode? Just wondering if the unusual winding arrangement is confusing the current sensing.
Try 'standard' mode if u haven't already.
Still perplexed!