Chinese Girl Machinist

[SmithDoor]

That may be the issue, some areas of China are still very poor so rebuilding may be the only affordable option, if you've ever watched the videos of rebuilds of equipment by central Asians, Pakistan, etc, you'll see people rebuild things that would never be rebuilt in most western countries but in fact the labor is cheaper than buying a new part, if they can get it!

Back in the 1960's you see rebuilding in America.
Today no wants used or rebuilt maybe a car.

Dave

 

[willray]

As I was watching one video, an Anime advertisement kept flashing across the bottom of the screen, LOL.
She is basically a live person anime character, or so it would seem.

What, exactly, does this even mean?

 

[Richard Hed]

That may be the issue, some areas of China are still very poor so rebuilding may be the only affordable option, if you've ever watched the videos of rebuilds of equipment by central Asians, Pakistan, etc, you'll see people rebuild things that would never be rebuilt in most western countries but in fact the labor is cheaper than buying a new part, if they can get it!

The thing here about expense -- that is, rebuilding is the only viable option -- I say no because the copper wire she is using is very very expensive. Had she used "used" copper wire, maybe.

 

[willray]

I am somewhere between amused and saddened by the number of posters here who think they have a clue about the economics of machinery repair in China, especially more rural China.

The thing here about expense -- that is, rebuilding is the only viable option -- I say no because the copper wire she is using is very very expensive. Had she used "used" copper wire, maybe.

And how does the fact that the wire is expensive, negate the fact that in an economy where such motors are not commodity items, the wire alone, would be vastly cheaper than a new motor containing the wire?

I can buy a new commodity motor off the shelf, much, much cheaper than I can have an existing commodity motor frame rewound. I can have the custom-frame motor for my Monarch rewound, much much cheaper than I can buy a complete new replacement motor.

 

[minh-thanh]

Hi Richard .

The thing here about expense -- that is, rebuilding is the only viable option -- I say no because the copper wire she is using is very very expensive. Had she used "used" copper wire, maybe.

Electrician who rewinds copper wire for any motor never use used copper wire !
In my country , Rewind an Electric Motor is always much cheaper than buying a new motor - Electric motor from 1/2 hp to hundreds of hp or more .
And I'm sure she used new copper wire .

 

[aarggh]

I have to guess that these videos are staged to some extent, because the person always has clean clothes on, without a spec of dirt on their body.

I've seen that sort of thing on a lot of channels, and have always wondered what it is I'm doing wrong, as my clean tops seem to get dirty when I just walk past my shed, let alone do any work! Drives my wife nuts cause practically every top or shirt I own is in some sad state of disrepair!

 

[Toymaker]

I live in Thailand, which is part of the geographical area known as South East Asia; you cannot believe how inexpensive labor, even skilled labor, is in this part of the world. A few years back I had a welding shop fabricate a frame for my DIY lathe; dimensions are roughly 56" long x 29" deep x 22" high. Steel tubes are 1.5" square.
Total cost for the entire frame, labor & metal, was $250 US. I suspect the price would have been even less in China.

There's no doubt in my mind that repairing old motors in China is much, much cheaper than buying a new one.

 

[L98fiero]

I've seen that sort of thing on a lot of channels, and have always wondered what it is I'm doing wrong, as my clean tops seem to get dirty when I just walk past my shed, let alone do any work! Drives my wife nuts cause practically every top or shirt I own is in some sad state of disrepair!

That's a kind of funny comment.
When my son was ~5 years old he and the two Chinese boys from next door would play in the back yard, he'd come back in with grass and dirt on his clothes and the other kids, who came wearing white shorts look as clean as when they came over. No idea how that happened.

 

[Nikhil Bhale]

I live in India and we follow the same principles as rest of Asia. If it is broken fix it and fix it more. Old things never get thrown out because they are not working or have become old.
But in USA things are different. One time my ship was calling some ports in USA. Houston, Tampa, Jacksonville etc. We had a motor winding short/ breakdown onboard. We asked our agent about cost of rewinding the motor on shore. The cost agent suggested for rewinding was more than the cost of a brand new motor. So we opted to buy a new motor.

Regards
Nikhil

 

[GreenTwin]

I have seen the same thing with motors.
It often costs more to rebuild a motor than to buy a new one.
Labor costs I guess, and OSHA, EPA, and a slew of other business regulations.

And for non-critical applications, it does not matter so much how the repair is done.
I have seen some repairs done that worked, but I question how long the part will last.
You would not really save any money with a repair that did not last long though.

Sometimes the motors are so old that replacement is not possible, because they don't make old motors anymore, and a gearbox would be required to step the speed down.
We had these motors rewound, and the are about 500 rpm, 110 years old.
The new process used the epoxy/vaccum on the rotors.

The key to making a large motor last is to put heaters on the stator, to always keep the windings above dewpoint.

 

[Zeb]

The thing here about expense -- that is, rebuilding is the only viable option -- I say no because the copper wire she is using is very very expensive. Had she used "used" copper wire, maybe.

I've seen hundreds of feet of stripped power lines overseas.
There's some pretty amazing Pakistani videos on casting iron and rebuilding starter motors. What I also appreciate is that ordinary folks are able to share their content in a raw format. You see workers get grouchy with their boss and walking around bare-footed near molten lava.

@GreenTwin That rebuild is amazing! And I love the Allis-Chalmers brand...particularly the tractors.

 

[minh-thanh]

I have seen the same thing with motors.
It often costs more to rebuild a motor than to buy a new one.
Labor costs I guess, and OSHA, EPA, and a slew of other business regulations.

And for non-critical applications, it does not matter so much how the repair is done.
I have seen some repairs done that worked, but I question how long the part will last.
You would not really save any money with a repair that did not last long though.

With special motors I don't know,
But most electric motors in large industrial workshops, from 1/2 hp to hundreds of hp.., from Chinese motors to big brands like ABB, are rewound with copper wire and have a very long life. ( Of course, that depends on the worker, how to rewind the copper wire, the type of copper wire, the brand of the wire, the insulation glue....when assembling, all bearings should be replaced )
And I can assure you that in my country, rewinding is always a lot cheaper than buying new and I am sure of their durability. Sure !
Every place is different, so I won't discuss this anymore

 

[GreenTwin]

In the old days, you could often walk into a foundry or manufacturing plant without too much trouble.
I got to tour a large local foundry many years ago, as well as a large tire manufacturing plant.

It is very difficult to get into any plant these days, for tours or anything else, and thus I guess the reason people travel to India, Pakistan, Malasia, etc. to see how things are actually built/made.

The client wanted to scrap those motors and use new ones with gearboxes. I told them "No Way !".
I was able to convince them that rebuilding these motors would give then a configuration that would last another 110 years, which is how old these motors are.
There is no new motor that will last 110 years.

Allis Chalmers is an iconic brand for sure.

There are some interesting sugar mill videos out there.
Check out the big Corliss. Still going strong after who knows how many years (100 +).

A large machine shop in the second video at 23:25.
You can bet there are some talented machinists and mechanics working in that mill.




.

 

[GreenTwin]

I have seen several repairs of truck drive shafts that have sheered off.
They just weld the two pieces back together, and put it back on the truck.
I have to guess that the axle is a very high strength piece of steel, and so I question if just welding it back would give the necessary strength for a truck axle.
I have seen a lot of cast iron truck blocks welded back together rather haphazardly, and while I know you can weld/braze cast iron, there is a certain method to prevent cracking.
And wherever a motor is rebuild, much depends on the person doing the rewinding, and the materials used.

A motor guy told me an interesting story about a steel mill that had a moving gantry crane, and they would pick up a huge piece of steel, roll it to another area very quickly, and use the motor to brake. They kept burning up motors.
My motor buddy rebuilt his motor using very high temperature windings and insulation, and state of the art vacuum epoxy impregnation technology.
The motor did not fail anymore under load, but the two large shafts connected to the motor sheered off.

The motor rebuilding industry is an interesting one.
Cast iron motor end bells make for good consistent gray iron scrap, to use in casting engine parts.

And you can build up babbitt bearings with a torch.
I saw this method in use, and never new you could do this (photo below).

And the blue thing below is a 10 foot diameter vacuum chamber.

 

[Richard Hed]

Whoa! I'd like to have that in my back yard. Does it run off 110?

I have seen the same thing with motors.
It often costs more to rebuild a motor than to buy a new one.
Labor costs I guess, and OSHA, EPA, and a slew of other business regulations.

And for non-critical applications, it does not matter so much how the repair is done.
I have seen some repairs done that worked, but I question how long the part will last.
You would not really save any money with a repair that did not last long though.

Sometimes the motors are so old that replacement is not possible, because they don't make old motors anymore, and a gearbox would be required to step the speed down.
We had these motors rewound, and the are about 500 rpm, 110 years old.
The new process used the epoxy/vaccum on the rotors.

The key to making a large motor last is to put heaters on the stator, to always keep the windings above dewpoint.

View attachment 137305View attachment 137306View attachment 137307View attachment 137308View attachment 137309View attachment 137310View attachment 137311

View attachment 137312

 

[GreenTwin]

12,500 volt. Pretty high for a motor, generally speaking.
Most I see are 5KV.

.

 

[stevehuckss396]

Not high for a large motor. I hooked up 3 at marathon in Detroit. 13,800 volt. 2 were 7,800 hp and one was 10,000 hp. The largest motor I have hooked up was at national steel in Delray. It was 22,500hp. They had to give detroit edison a 30 minute heads up before starting that one.

 

[GreenTwin]

I have worked on some 5,000 hp at 4,160V, and they have to notify the utility company when they start them.
About 500 amperes or so, and so the cables are not excessive.

As you go up in horsepower, the cables would get rather large at 4,160, and so the higher voltages would be worth the trouble for the extra insulation.

I use 5kv above 200 hp. I have not had to go above 5kv for the largest motor, which was 5,000 hp.
The local refinery has blower motor, I think rated 20,000 hp and 40,000 hp. I have seen then from a distance. Big as a house.

The big Allis Chalmers motor above is a wound rotor induction motor.
I went back and checked, and the voltage is 6,250 v, 750 hp, 115 rpm.
I think when they were installed in 1915, the local power system was probably not very stiff, and thus the wound rotor to minimize the starting surge.
I recall the incoming switchgear operating at 12.5 kv, so I guess they moderized the power system, and installed step-down transformers.

The Allis Chalmers motors are a beauty to watch run.
Runs as good as it did when installed in 1915.
The three brushes are for the wound rotor.
You can see that the base is designed to allow the stator to slide over off the rotor.

 

[William May]

I used to drive by a "General Electric Heavy Apparatus" repair facility in Tucson. I think most of the motors were from the huge electric dump trucks they used at the local copper mines and some equipment from rail locomotives. I know every day when I went past, there were a couple of semis pulled up, with a giant shop crane hooked up to them to lift the motors and other drive parts off, and transport them into the shop for repair. The last time I went by it, the signs had been changed to "ABB Heavy Apparatus", so I guess the Swedes bought the place.

 

[GreenTwin]

Looks like about 420 amps for a 10,000 hp induction motor at 13.2 kv.
You could feed that with one cable run.

Several of the 4,160v motors I have dealt with are synchrounous, with exciters on the shaft, and remote.
Seems like a large motor would have to be synchronous to avoid a big power factor charge that could occur with an induction motor.
.