opinion; old German milling machine

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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Bill Shields
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Re: opinion; old German milling machine

Post by Bill Shields »

Be careful about manually activating relays. There is the possibility that you can cause a short and burn up something.
Too many things going on to bother listing them.
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liveaboard
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Re: opinion; old German milling machine

Post by liveaboard »

Powering up the relay coils, that's a good idea. A bad coil is likely, and if found easy to change.
Some of them have manual buttons but most don't.

One will self energize and latch, until I press the spindle brake relay next to it, then the first one releases. Clues...

I'm planning to make a 220v test light with a long wire to attach to the isolation transformer. Then I can hunt around for where control current is and is not.

So much is not working, like the spindle brake relay button for instance, that there has to be a chunk of control circuitry that's just not being energized.

Hard to tell with the mercury switch wires; I had the same thought, their girth should predict the power they switch, but they're short with braided flex insulation sheath, and disappear into a hole.
Could be for significant power, or not.
Probably not, whoever designed this likes big old contactors for power.
I'm thinking the function is to function as a pre-ic chip delay relay?
The thing was built in 1975, they must have had electronic delay relays even on the other side of the iron curtain. But I haven't found a single bit of silicone anywhere, except for a diode block for the clutch coils that looks like the 60's revisited.
They're not for machine tilt. Each has 3 tubes on a single pivot activated by a little tiny servo motor.

More news later.
John Hasler
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Re: opinion; old German milling machine

Post by John Hasler »

Do you have a multimeter to check coil resistance and trace connections?
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liveaboard
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Re: opinion; old German milling machine

Post by liveaboard »

Of course, I have 3.
But I find that sometimes a test light works better. Multimeters pick up leak currents and display a voltage.

Anyway...

Using Russ's idea, I tested all the relay coils. One is faulty, the one that activates the spindle brake, but it has 4 NO connections so it might do all sorts of things, and be the only problem, or not.

While the upper control plate was out [6 momentary buttons with a rats nest of wires behind them] one of the contacts touched the aluminum case, and a relay latched on.
Then, like magic, the machine started working. somewhat anyway.
Feed worked, fast speed worked, spindle worked.
After shutting it off, nothing works again.
So at least I know the clutches and feed is mechanically sound.

Wednesday or Thursday when I go into town I'll buy a new relay and a fistful of indicator lights. I want each relay to have one.

Meanwhile, other work. Some adaptors, a fitting to fill the oil [it has to fed through a horizontal bolt hole with a non-standard thread].
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liveaboard
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Re: opinion; old German milling machine

Post by liveaboard »

The story continues;
I installed and wired a new hi-low spindle switch, it's a tight fit but it's done.
speed switch on bracket.jpg
spindle gear change box with new speed switch.jpg
Then I noticed that the safety cutout button for the belt cover looks very similar; I bet if I open that box, there's an identical switch that would have screwed right in.
Oh well, no matter.
broken speed switch and belt cover safety switch.jpg
I got the new relay and fitted it.
Nothing.
Well, the spindle brake works now but that's all.
I went and checked the dead realay that I'd assumed was 4x NO
WRONG!
It's 3x NO + 1X NC. Well, it would have been once, 2 of the contact sets were cooked.
There are probably more cooked switches still to be found.
old relay with NO NC symbols.jpg

It could also be that there's another cutout somewhere stopping the motors from switching on, maybe an oil level sensor on the cutting oil reservoir?
Would that be normal in an old mill?


It will work... but tomorrow is dentist, then I have to mow, strim, and look after the trees.
Then I'll get back in there and jump the wires that should be on the NC contact of the spindle brake relay. It's quite likely that's a motor cutout circuit.
electric box full.jpg
pete
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Re: opinion; old German milling machine

Post by pete »

A sensor for the cutting oil level? Probably not, but no way for me to be 100% sure of that. It would be unusual, but it's East German so???? Frustrating having those electrical issues, but they could be a blessing. Once the machine died it likely got shoved in a corner. So I'd guess it may having been sitting and doing nothing for a long time. Expect dried oil / grease to create some minor drag issues until it's been run for awhile. With the lack of rust it was at least kept in a heated environment and not robbed of parts for other machines. Or mice getting into that wiring and chewing it all up. But if it's been sitting for years leaking oil seals might be a further issue you'll find once it's back running.
Russ Hanscom
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Re: opinion; old German milling machine

Post by Russ Hanscom »

A most impressive control panel.
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Bill Shields
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Re: opinion; old German milling machine

Post by Bill Shields »

you look at this and begin to understand why used, non-running CNC machines (particularly those with tool changers), go for pennies on the ton...except to people (like me) who strip them down to basic iron and completely replace anything that was ever intended to see electricity.

believe me, I am totally sympathetic to your case and what you are going to have to go through.

you are attacking it correctly - replace all the faulty switches and relays that you can find and see if it works....THEN look at the wiring.

don't move any wires from their existing / current location until you have gone through this replacement process.

A chart that shows what wire number is @ what position on what component will be very helpful in the future when you have 2 wires 'disconnected' and cannot remember which wire goes where.
Too many things going on to bother listing them.
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liveaboard
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Re: opinion; old German milling machine

Post by liveaboard »

Thanks;
I put a jumper wire across the NC wires on the replaced relay, to no effect.
The control circuit wires are yellow and blue; most of the spaghetti that runs through all those switching relays is yellow.

The big power relays that switch the motors have no power at the blue, but I haven't Figured out the path of that so far.
I'll get back on it in a few days.

I'll have to order relays by mail and wait. I'm going to try and test more circuits first, the one I took out is an east German original and 2 of the 4 contact sets were not contacting anymore.
There are 4 more E.German relays remaining, and they're each a complex mass of wires on 8 NO + NC switches.
Others have been changed at different times; who knows if they were wired correctly?

I'll probably have to spring $50 for that wiring diagram.
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liveaboard
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Re: opinion; old German milling machine

Post by liveaboard »

News flash; someone from the German group sent me a wiring diagram!
John Hasler
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Re: opinion; old German milling machine

Post by John Hasler »

Since it sat for many years I'd go through and clean and burnish every contact pair and then check with an ohmmeter that they made and broke when operated manually.
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Harold_V
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Re: opinion; old German milling machine

Post by Harold_V »

Good luck! The diagram should be most useful.

I own an Overbeck (German) universal cylindrical grinder with a drop-down internal attachment. It was purchased from one of my customers when I was actively machining commercially. It was in service (I actually removed it from the plant where it was in operation), but, unbeknownst to me, it had been altered to perform a given way, apparently having been used for a given product only. I was not aware that that was the case, as it was put in storage in anticipation of our move to Washington State, and not wired until we had completed our construction project (shop and house). I had owned it for more than 20 years by then.

I was fortunate to get the manuals with the machine, but my electrical skills are limited. After I had pursued it as far as I could, I turned to my trusty friend Patio (on the board here) who is an electrician. His persistence paid dividends. Turns out one wire had been removed from a solenoid, and it wasn't obvious. The machine now operates as it should. Thanks again, Patio.

H
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