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DIY Welder Project

dkamp

eMail NOT Working
Joe... what you're considering here is most frequently referred to as an 'underhood welder'... and it's much, much, much simpler than what you're probably thinking.

You need either the largest alternator you can find, or several small ones. A 100A car alternator is a good start... and if that three-cyl Suzi motor will mount up say... three of them, you'll be fine.

The concept of the underhood welder is about one step above just wiring three car batteries in series.

First off: Disable the alternator's internal voltage regulator. Yank it out, and wire the field, through a switch, to the battery. Full 12v in = full alternator output voltage and current.

Next, put in the most beastly strong three-phase rectifier bridge that the alternator will accept, and put it on a big heat-sink. You can find common ones to fit alternators commercially, or you can buy six stud-mount diodes and bolt them to an aluminum heat sink, insulated on standoffs...

You'll hook one of your welding leads to the bridge +, and the other to bridge -.

Don't bother trying to govern the engine with anything fancy. Start the engine, and shove a screwdriver between the throttle plate and idle stop, or put a boat-type throttle lever on a short cable. Bring it up to some arbitrary speed, turn on the field, and attempt to strike an arc. If it's too hot, back off the engine speed a little... and if it's not hot enough, add more throttle.

The engine WILL slow down a bit when you start the arc. If you're asking too much of the belt, it'll slip, so go with two. If the alternator starts getting hot, you'll need to parallel in a second alternator to carry the load.

If you're REALLY gonna make a multi-year project out of this, it'd be best to get your hands on a suitcase wire-feeder and a reliable source of welding wire... but the biggest problem I see, is that if your workside cannot be secured against theft of tools, you're probably gonna lose your welding cables, and probably anything else that's there.
 

uglyblue66

Subscriber
Last Subscription Date
11/07/2018
I beleive I would just stay in the US where I could get a decent welder.OR value your time over the dollar and just take a welder over there and pay the dues.By the time you get something put together,it smokes twice and puts you behind 6 months on your project,the few 100 bucks you saved on shipping and taxes would not look near as exspensive.
 

JoeKultgen

Registered
Great article! They did sort of skim over why they're *THE* boat here. (Actually it's my understanding that banca or bangka is the Filipino word for boat.)

The Philippines is an island nation, roughly 7,300 of them. Less than half are populated. Of those, less than half have roads. Maybe a couple dozen islands are large enough and have enough road miles to make a truck useful. There are short, cab over, fifth wheels that we would call yard trucks in the states hauling cargo containers away from the docks. I don't think there's a single 18 wheeler in the whole country.

All the heavy lifting goes by water. If you want to get your car or truck to another island you have to put it on a ferry. It doesn't take much of that to eat your budget. Even if you don't care about the cost, they have limited schedules and destinations. "Road trip" here translates to "island hopping". If you haven't got a boat I'd say almost 90% of the country is inaccessible.
 

JoeKultgen

Registered
If you are going to go the 'cheap inverter welder' route, i'd be tempted to tear into the welder, and try to feed the DC internal buss with the alternator.
It looks like we're getting to the same place by different routes. Now it's just a matter of shopping for "off the shelf" hardware that gives the best balance of price to how much effort it takes to modify it.
 

JoeKultgen

Registered
You need either the largest alternator you can find, or several small ones. A 100A car alternator is a good start... and if that three-cyl Suzi motor will mount up say... three of them, you'll be fine.

... but the biggest problem I see, is that if your work site cannot be secured against theft of tools, you're probably gonna lose your welding cables, and probably anything else that's there.
Good suggestions! The Geo engine is just for testing different configurations stateside, so that I don't waste money shipping something that doesn't work. On this end I'll be using a second hand 3 cylinder diesel that will eventually be re-purposed as a boat engine. I'll probably leave the alternators mounted and keep the welder handy for repairs. Everything breaks sooner or later.

People here are more honest, on the average, than the folks I knew stateside. But they are poor, too many of them are starvation level poor. I hear now that back in California the cops will no longer arrest anyone for shoplifting. The local mall cops carry short barrel, pistol grip, pump shotguns. I've seen one with an M-16. It's mostly an anti-terrorist thing but they are still store security. I won't say shoplifting doesn't happen. The people who do it for a living don't have much of a life expectancy.
 

uglyblue66

Subscriber
Last Subscription Date
11/07/2018
I have what I think is a Winco welder that had a wisconsin robin engine when I got it .It uses a huge alternator like the cab over Ford truck we used to have at the station.It worked good.I would have to look at it and see what the amps was on it.I know I could use 7018s with it no problem.Built my camper and my first 10 foot utility trailer with it.Had to install a 10hp briggs because the robin threw it's flywheel at me at full rpms!
 

JoeKultgen

Registered
Square two

I did a little more research. It seems that the reason Onan gensets are such boat anchors is because the most efficient way to turn mechanical motion into 60 Hz AC (when cost and weight aren't high priority), requires lots of steel laminations and a crap load of copper.

Where cost and weight are the governing factors you get much better performance from a multi-pole rotor driving stator coils just large enough to get close to full magnetic saturation before the field is reversed. The alternator on a modern jet airliner is most likely 400 Hz 3 phase AC. The common standard for rating automotive alternators calls for full load at 6,000 RPM, which also happens to deliver roughly 600 Hz 3 phase before it's rectified. Spinning it faster doesn't hurt anything but it doesn't make any more power.

The largest commonly used automotive alternator is around 165 amps in stock form. That's with the stator connected in a Y (or wye) configuration, changing it to delta bumps the output to around 300 amps and reduces the chance of catastrophic failure if the alternator or load drops one phase. Units rated at over 165 are usually wired delta "off the shelf".

The down side is that doubling the output increases the heat produced by a factor of four. A unit that will run all day at a full 165 amp load can turn into a smoking wreck in a relatively short time at 300. Another peculiar thing about alternators is that the current flow is load dependent. A unit loaded at 165 will deliver that if it can. It won't do more than it was built for. A 300 amp unit loaded to 165 will deliver that and run at about the same temp as the lighter unit, but still have a reserve capacity available for sudden momentary loads. Putting a high output alternator on a car or truck that isn't overloading the stock unit mostly helps to keep your bank account from getting over loaded.

Volts x amps = watts

You can do 12vac @ 165a or use a transformer to get 120vac @ 16.5a with relatively minor internal losses. Either way is 1,980 watts or just short of 2kw. While the frequency may have a huge effect on how certain circuits operate it doesn't have much to do with available power. The Amico 140 I owned had a rated input power of 1.6 KVA with a PF of .85, that works out to 1,360 watts. So, in theory at least you could use the output of a single 165 amp alternator to drive the thing and the welder would kick out from exceeding it's duty cycle before overloading the alternator. I could weld more or less continuously with 3/32 rod at 85 amps. I wasn't getting much penetration but could lay down practice beads and it was getting enough rest when I changed rods or checked my work to keep from tripping out.

At this point I see two viable ways to go.

Take 3 phase AC directly from the stator and find a solid state way to convert from 600 Hz to 50-60 Hz then use transformers to get 380v and feed it into a 3 phase welder like this one.
https://www.amazon.com/FASTTOBUY-Welding-Advanced-Inverter-Equipment/dp/B07XG72DVJ/ref=sr_1_12?keywords=3+phase+IGBT&qid=1575762145&s=hi&sr=1-12&th=1

OR

Modify the alternator to work as a welder directly like these guys do.

https://www.zena.net/htdocs/welders/weldinf.shtml#Top

If you go to their list of reasons why their welders are *not* automotive alternators every modification they list with the exception of their patented control system is pretty simple. I've run across a YouTube video by a guy who reverse engineered one of their early model controllers. I can do quite a bit of experimenting for the price tag they have on a plug and play system. (over 4 figures)

Either way it looks like I'll be running at least two alternators in tandem to get the power level I want without frying the windings.
 

pegasuspinto

Registered
Once again, of those two, I would modify the alternator to put out high voltage DC, and open up the welder and feed the DC internal buss of the welder directly.

Inverter welders take the input power, immediately rectify it to DC, and then run that DC into a high frequency inverter, and feed a transformer, where the output is again rectified to make DC.(or potentially left as AC to weld with AC) At high frequencies, the transformer can be smaller.

The internal DC bus will be about 1.4 times the voltage as the AC input. For instance, a 120v inverter welder will have about a 168 volt internal DC bus. The welder shouldn't care where it gets it's 168 volts of DC from.

To convert frequencies, the normal way to do it, is once again, rectify to DC, then invert it back to AC at the desired frequency. The problem is, to get 20A or so of 120vac at 60hz, will take a big 'ol chunk of iron, and it's usually a special transformer, to allow the push-pull type 'mirror' configuration usually used on the input side..

If you really want to go this route, I'd just use stock alternator(s), and feed a off-the-shelf modified sine wave inverter, the biggest one you can get. You can use a battery in this case to help adsorb surges and use a smaller alternator, in fact the same battery as you use to start the engine.

In my mind, you're close to a good answer, but don't get too hung up on inventing a square wheel.
 

JoeKultgen

Registered
Inverter welders take the input power, immediately rectify it to DC, and then run that DC into a high frequency inverter, ...
...In my mind, you're close to a good answer, but don't get too hung up on inventing a square wheel.
Thanks! I'v'e been poking around looking for info on the input stage of the inverter welder. The model I linked in my last post is modular, at least to the extent of having several different input boards available in 1,2,and 3 phase spanning voltage ranges from 110 to 540.

{rant}
Search engines keep pointing me at YouTube. I'll see a video with a relevant title, and a clear, concise blurb (in English) that leads me to believe it's something I really want to know. Then I click on it, and the narration is in Chinese, or Hindi, or English with a Pakistani accent so thick he can't be understood here or in his home country. On top of that, the video doesn't have captioning and does have the most annoying sound track available at a volume that drowns out half the narration I can't understand to begin with. Don't even get me started on the camera work.

The only area where these videos shine is SEO. *THAT* they have spot on perfect. There's a yard long list of every key word I can think of for what I want to know, in clear properly spelled English. Each of those words is spoken in the first three minutes of the video, usually more than once, in clear accent free English, making them the only understandable words in the narrative. They're engineered to get the best possible ranking out of the YouTube search algorithm with complete disregard for whether or not the video itself offers anything useful to a human. I must already be crazy. It's the only possible thing that could keep this from driving me nuts!
{/rant}

This seems to offer about the best balance of price and features for what I'm trying to do.
http://amicopower.com/index.php?route=product/product&path=87&product_id=158&sort=p.price&order=DESC

They're not the cheapest but darn close to it and I've had good experiences with their products in the past. I'm going to drop them a note regarding unusual power sources. While waiting for a reply I'll be searching for schematic diagrams to see what I can learn on my own. Any links you can post would be a great help.
Thanks again.
 

kwfiggatt

Registered
Thanks! I'v'e been poking around looking for info on the input stage of the inverter welder. The model I linked in my last post is modular, at least to the extent of having several different input boards available in 1,2,and 3 phase spanning voltage ranges from 110 to 540.

{rant}
Search engines keep pointing me at YouTube. I'll see a video with a relevant title, and a clear, concise blurb (in English) that leads me to believe it's something I really want to know. Then I click on it, and the narration is in Chinese, or Hindi, or English with a Pakistani accent so thick he can't be understood here or in his home country. On top of that, the video doesn't have captioning and does have the most annoying sound track available at a volume that drowns out half the narration I can't understand to begin with. Don't even get me started on the camera work.

The only area where these videos shine is SEO. *THAT* they have spot on perfect. There's a yard long list of every key word I can think of for what I want to know, in clear properly spelled English. Each of those words is spoken in the first three minutes of the video, usually more than once, in clear accent free English, making them the only understandable words in the narrative. They're engineered to get the best possible ranking out of the YouTube search algorithm with complete disregard for whether or not the video itself offers anything useful to a human. I must already be crazy. It's the only possible thing that could keep this from driving me nuts!
{/rant}

This seems to offer about the best balance of price and features for what I'm trying to do.
http://amicopower.com/index.php?route=product/product&path=87&product_id=158&sort=p.price&order=DESC

They're not the cheapest but darn close to it and I've had good experiences with their products in the past. I'm going to drop them a note regarding unusual power sources. While waiting for a reply I'll be searching for schematic diagrams to see what I can learn on my own. Any links you can post would be a great help.
Thanks again.
Here's a guy who homebrews a welder from an alternator. -->

His lump started out using the aircraft genny talked about previously, but that smoked and he went with the automotive alternator. It might be worth dropping him a line if you're intersted...

Kevin
 

JoeKultgen

Registered
Here's a guy who homebrews a welder from an alternator. -->

His lump started out using the aircraft genny talked about previously, but that smoked and he went with the automotive alternator. It might be worth dropping him a line if you're intersted...

Kevin
If I can't get something together on my own there is always plan B.

https://cntongbo.en.made-in-china.com/product/NCpnZODlAJkR/China-SD-Sdc-Series-Welding-Generating-Dual-Use-Alternators.html

That price is FOB Xiamen. It could easily double or triple by the time a shipping agent gets it through customs and tells me which dock to pick it up. The good news is that China is less than a week away by boat. When it does get here. I can hire a local boat to pick it up and deliver it to the build site without having to fight wheeled traffic.
 

dkamp

eMail NOT Working
Something that one must understand... getting a high power rating is one thing... I've got a chainsaw that'll knock out something like 8.6hp from 120cc...
and I've got a four-cylinder liquid cooled 1000cc motor rated for barely one HP more...

The company has a MillerMatic 250 wire-feed welder that's the same physical size, but a couple hundred pounds lighter than my Miller CP200

The difference is that my four-cylinder liquid cooled engine from 1950 will run for a decade at 9hp with NO maintenance, while the Stihl MS-880 will not...

And the MM250 will overheat at 200A if run more than 160A in continuous duty. The CP200 will run at 200A all day, continously, on a hot day, and never break a sweat.

You can spend LOTS of time trying to re-engineer the automotive-alternator-welder concept, and in the end, it's still a car alternator. Install two of 'em on your engine, wire them for Delta, connect to welding leads, and start burning metal. When they get hot, they'll start smoking, and your welding power will drop off a bit. Don't expect miracles, be conservative in your rod diameter. You'll have to meter your demand to not overrun your capacity.
 

turtmaster

Subscriber
Last Subscription Date
10/03/2019
Joe, if you were going to get an inverter welder, may I recommend a "hitbox" I have a "Arc 160d" with lift-arc tig, 220v input, 160a Max , about the same price range as the amico, the hitbox, Runs 6011, 6010, 6013, 7018, Rod's just fine, in both 3/32" and 1/8" matter of fact, my boss, who studied welding while in the Army, years ago, anyways, he liked it so much he bought one for himself yes, I think he said, he ran something like 50 lbs of both stick electrodes, and Tig wire through it!, Anyways, I measured with mine, 170 amps!, short circuit current, with the electrode purposely stuck to the workpiece, remind you that is through 48 feet total, of welding cable, for the work and Stinger leads, of 6 awg, welding cable, yes 6 awg! So, if you ask me that welder is performing above specification!

Sorry I misspoke, it should say 177 amps !!!
Here's the video of the test.

 

JoeKultgen

Registered
I'm still exploring options. My main incentive, aside from the pure joy of putting together something interesting, is that I have to buy a prime mover for the finished boat in any case. It doesn't have to be huge. I'm looking for a top speed of 10-12 knots. With the hull shape and wetted area I have in mind that would require something between 20 and 35 HP. I might be willing to drop that some but if so I'd rather throttle back a 20 than flog a 12. For health and safety reasons it has to be diesel. When the hardware is in your living space, gasoline isn't viable.

It makes sense to me to buy the engine at the start of the project. After using it to power the generator, welder, air compressor, plasma cutter and smaller power tools during construction, I'll relocate it to the engine bay. When not turning the prop it may well continue with it's original uses. You never really finish building a boat, not one that's in daily use in salt water anyway. Most of the local Banca's are marine plywood over a light wood frame, held together with copper nails and boat bondo (marine epoxy). The builder shows up on an unused stretch of shoreline with his hammer, chisel and saw, then pulls out a cell phone to tell the hardware store where to drop the lumber. It takes them about a month to build the size I want, though they can cut that in half by hiring a couple of trained helpers. Finished hull would cost me about $500 then another $400-$600 for a good used diesel engine and prop.

The problem with going that route is that they start to rot before they're even launched, while the lumber is getting rained on during construction. Between that and marine borers you're patching in a couple of months and lucky if you get three years before having to completely re-skin the thing. The up side is that if you don't actually sink repairs are fairly inexpensive. The down side is the size of that *IF*. With a steel hull, if you stay on top of it grinding, welding, and painting as needed you can go twenty years before it's getting thin in enough places that it's time to break it up. The largest known tidal range here is a little over eight feet while the average is closer to six. A wood hull version of what I'm planning has a draft of a little over a foot. The first run of rough numbers puts me at around 20" on a 4 foot tall hull. So I should be able to beach it and work on any part of the hull while the tide is out. The country is over 7,000 islands, while white sand covered with bikini babes is kind of scarce there is no shortage of waterfront where nobody will give you crap about doing some boat repair.

I started this hoping I could cheap out with an alternator based home built rig. Unfortunately, automotive alternators have been thoroughly engineered over the years until they fill their niche perfectly and are a rather poor fit for anything else. It seems to be coming down to a choice of an engine powered welder that also has some generator capacity, or a generator substantial enough to run the other tools including a usable welder. Right now I'm leaning towards the second option. It's usually more cost effective to buy selected tools that each do one job well than a multi-function device that keeps breaking some functions while others never get used.
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
Sounds like a neat project. I’m not sure how expensive or difficult to obtain fuel is where you’ll be working, but aside from very low duty cycles, automotive AC generators are notoriously inefficient. I’d say they’re fine for doing light repairs, but it would take a boat load of them to build a whole boat.

Now that we know that you will have an engine and do not need a welder generator set, but rather just the generator itself, how about keeping an eye out for something like this. This generator is belt driven.

https://www.smokstak.com/forum/threads/general-electric-welder-generator-set.173770/

Alternatively, something like this could weld all day long.

https://www.smokstak.com/forum/threads/bought-a-28-volt-300-ampere-generator-today.179628/

Welding up a hull out in the open, I can only imagine that stick welding is the only way to go, so any suitable direct current source ought to work beautifully. Suitable is the keyword. I don’t think any automotive generator will be suitable. Even a big one from a truck.

MAYBE a BIG one from a bus meant to supply all of the fans and blowers for an A/C system. They even make oil cooled ones. That may be your best bet, since my two earlier examples are a little hard to come by these days.

Best of luck! And start a thread for your boat when you start building it. Looks like fun.

Regards,
Keith
 

JoeKultgen

Registered
Sounds like a neat project. I’m not sure how expensive or difficult to obtain fuel is where you’ll be working, but aside from very low duty cycles, automotive AC generators are notoriously inefficient. I’d say they’re fine for doing light repairs, but it would take a boat load of them to build a whole boat.

Now that we know that you will have an engine and do not need a welder generator set, but rather just the generator itself, how about keeping an eye out for something like this. This generator is belt driven.

https://www.smokstak.com/forum/threads/general-electric-welder-generator-set.173770/

Alternatively, something like this could weld all day long.

https://www.smokstak.com/forum/threads/bought-a-28-volt-300-ampere-generator-today.179628/

Welding up a hull out in the open, I can only imagine that stick welding is the only way to go, so any suitable direct current source ought to work beautifully. Suitable is the keyword. I don’t think any automotive generator will be suitable. Even a big one from a truck.

MAYBE a BIG one from a bus meant to supply all of the fans and blowers for an A/C system. They even make oil cooled ones. That may be your best bet, since my two earlier examples are a little hard to come by these days.

Best of luck! And start a thread for your boat when you start building it. Looks like fun.

Regards,
Keith
There's an industrial surplus place a few miles from here. (Several of them actually but this one has a web presence.)
https://www.engineere.com/PH/Cebu-City/695402643904021/GEAR-Industrials
Their prices are high and it's buyer beware on condition. On the plus side most of their stuff is contractor grade and they don't have a problem with a serious buyer verifying that something works as advertised before putting their money down.

Right now they list a Komatsu KW-150 for P30,000 ($600) It should be something like this one.
https://aucview.aucfan.com/yahoo/g130487530/
What they'll have when I'm ready to buy is anyone's guess.
 
Last edited:

JoeKultgen

Registered
Still exploring assorted options. The sticking point keeps coming back to finding a large enough alternator at a price that doesn't exceed buying an off the shelf welder/generator. High output automotive units, especially those for big rigs or construction equipment, easily top four figures. The surplus aircraft units that sold for pennies on the dollar back in the fifties are pretty much gone. The few that remain are worth big bucks to the right people. Somebody restoring a vintage war bird will pay enough for the right NOS generator to buy a Lincoln SA 200 and a clunker pickup to haul it around.

Turning firewood into rustic furniture you sell to buy propane makes sense. Driving a propane delivery truck, taking your paycheck to the furniture store, and telling them to drop that heavy wood bedroom set next to the log splitter is insane.

It's my understanding that the primary difference between a motor and a generator is whether the same hardware is driving or being driven. There are refinements to optimize a unit for a given role but if you spin an AC motor at the right speed you get AC out of it. Used fractional HP AC motors are available as salvage, sometimes free for the hauling. A welder often draws more current than everything else in an average house combined. Used single phase AC motors you could spin for that kind of output are huge, rare, and much more expensive than a new generator head from Northern Tool. Also, synchronous AC motors are designed to run at a steady speed delivering a fixed HP at the least possible current draw. Driven as an alternator, a welder would knock them off their, "sweet spot", every time you struck an arc.

I may have found a way around this. In the US at least, high HP, AC motors are often available used for less than the cost of the copper windings. Check this out;

https://bakersfield.craigslist.org/for/d/bakersfield-allen-bradley-marathon/7056236390.html

New list on this model is around $4,000. That being the case, you're probably asking "why so cheap?"

There is a limited home market for 3 phase motors, effectively none at all for motors over 5 HP. On the industrial side, if you have a building full of these puppies, the electricity to feed them is going to be a significant portion of your operating budget. Installing a newer, more efficient, motor can easily pay for itself in a reasonably short time. Especially when you can charge off a piece of that as preventive maintenance. A motor this size isn't driving a trivial piece of machinery. It doesn't take much down time to destroy your bottom line. That is another reason this particular motor is selling at such a huge discount. If I were running a business that needed something this size, I wouldn't even consider installing it without first sending it to a reliable motor shop to have it completely checked out.

I'll be looking for an, "asynchronous", 3 phase motor. What makes this type of motor special is that it uses rotor windings connected to slip rings. By varying the resistance to the rotor windings you can modify the inductance, supplying full torque at start up and a range of motor speeds. This is very useful in an industrial environment. It should be equally useful when attempting to drive it as an alternator. I'll have to look around and see what is available here in the Philippines. I don't want to waste time and money experimenting in California only to discover I have a setup too heavy to ship and built with components I can't source here.

It should be interesting.
 

Heins

Subscriber
Last Subscription Date
01/02/2020
Still exploring assorted options. The sticking point keeps coming back to finding a large enough alternator at a price that doesn't exceed buying an off the shelf welder/generator. High output automotive units, especially those for big rigs or construction equipment, easily top four figures. The surplus aircraft units that sold for pennies on the dollar back in the fifties are pretty much gone. The few that remain are worth big bucks to the right people. Somebody restoring a vintage war bird will pay enough for the right NOS generator to buy a Lincoln SA 200 and a clunker pickup to haul it around.

Turning firewood into rustic furniture you sell to buy propane makes sense. Driving a propane delivery truck, taking your paycheck to the furniture store, and telling them to drop that heavy wood bedroom set next to the log splitter is insane.

It's my understanding that the primary difference between a motor and a generator is whether the same hardware is driving or being driven. There are refinements to optimize a unit for a given role but if you spin an AC motor at the right speed you get AC out of it. Used fractional HP AC motors are available as salvage, sometimes free for the hauling. A welder often draws more current than everything else in an average house combined. Used single phase AC motors you could spin for that kind of output are huge, rare, and much more expensive than a new generator head from Northern Tool. Also, synchronous AC motors are designed to run at a steady speed delivering a fixed HP at the least possible current draw. Driven as an alternator, a welder would knock them off their, "sweet spot", every time you struck an arc.

I may have found a way around this. In the US at least, high HP, AC motors are often available used for less than the cost of the copper windings. Check this out;

https://bakersfield.craigslist.org/for/d/bakersfield-allen-bradley-marathon/7056236390.html

New list on this model is around $4,000. That being the case, you're probably asking "why so cheap?"

There is a limited home market for 3 phase motors, effectively none at all for motors over 5 HP. On the industrial side, if you have a building full of these puppies, the electricity to feed them is going to be a significant portion of your operating budget. Installing a newer, more efficient, motor can easily pay for itself in a reasonably short time. Especially when you can charge off a piece of that as preventive maintenance. A motor this size isn't driving a trivial piece of machinery. It doesn't take much down time to destroy your bottom line. That is another reason this particular motor is selling at such a huge discount. If I were running a business that needed something this size, I wouldn't even consider installing it without first sending it to a reliable motor shop to have it completely checked out.

I'll be looking for an, "asynchronous", 3 phase motor. What makes this type of motor special is that it uses rotor windings connected to slip rings. By varying the resistance to the rotor windings you can modify the inductance, supplying full torque at start up and a range of motor speeds. This is very useful in an industrial environment. It should be equally useful when attempting to drive it as an alternator. I'll have to look around and see what is available here in the Philippines. I don't want to waste time and money experimenting in California only to discover I have a setup too heavy to ship and built with components I can't source here.

It should be interesting.
Here is a DC generator that will weld. I posted it when the new Smokstak started and I don't think it got transferred.
 

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