DC/AC welder?

drc_567

Joined Dec 29, 2008
1,156
It is difficult to tell from that picture what is happening.
Would it be possible to post a sketch or diagram of how you have arranged the 3 transformers? ... I.e. ... number of turns, priimaries, secondaries, series, parallel, etc.?
 

Thread Starter

ConstructionK88

Joined Jul 25, 2018
282
Diagram I'll have to do later. A rough estimate of secondary/primary turns/volts out is approximately 200 on primary and 16-20 on secondary. Each outputs 8v+-.5. I had to reduce the primary as it was quite large. I counted V&H wraps the best I could to guess around that 200. It's slightly thinner than the original primary as why I left so many turns. The 110v in is in parallel to primary wrap direction. Secondary's wrapped same direction and in series. Total V out is 27-32. The Amps I have no idea. Anything else please ask, I really want this to work again hahaha. I feel like it's the primary coil but I'm not sure.
 

drc_567

Joined Dec 29, 2008
1,156
It seems that you could achieve the most secondary amps by putting the primaries in parallel. Then place the secondary windings in series, using just enough turns to achieve the required voltage ... The original transformer primary windings are likely wound having a given polarity, ... a particular winding direction, so there would be some trial and error testing on the secondary windings in order to get the wrap direction and turns ratio to be sufficient.
If this scheme doesn't work, then you have probably exceeded the volt*amp design capacity of at least one of the transformers. The basic transformer rule is V*I in equals V*I out, with respect to primary and secondary windings.
...
 
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Thread Starter

ConstructionK88

Joined Jul 25, 2018
282
The primaries are in parallel. the seconds are in series. the wraps are only off by less than 10% stated. All give 8v out with little margin {ie 7.5to8.5}. Some second wraps are only 1 or 2 off so i dont think my seconds are the issue. Im sure the primaries are the problem but since the wire is a bit thinner im worried reduction would cause overheating. as they are now there is little heat but the amperage is a bit low. Close but low. I can liquid cool them but since the new primary is thinner would that reduce the amperage or does it matter? I am using the original secondary as my primary since the original primary had multiple wraps to include 110v, 220v, 277v, and another im not sure the purpose. The original secondary is only slightly thinner and had just 2 Vouts. The total V out id like to be around 40v but i dont care, neither does the welding rods, so long as the amperage is high enough. I proved itll work but my MOTs burned out due to careless abuse during breakdown and subpar rebuilding. primaries were loose and i probably nicked them.
 

shortbus

Joined Sep 30, 2009
10,050
While I don't quite understand why your doing things this way, I don't think you will end up with something that you think you will. Never saw a stick welder using multiple transformer cores. Adding your secondaries in "series" will only give you more voltage, not amperage. Transformers or batteries the results are the same, series expands volts, parallel expands amps.

Using a MOT secondary for a primary isn't something I would recommend to anyone, the wire gauge is too thin.

Don't know where your from but around here a old "tombstone" type stick welder is a very inexpensive item to buy.
 

Janis59

Joined Aug 21, 2017
1,894
RE: Shortbus
I have seen. But them are always in series, just in one core one may get a max max 1/2 mm welding on some 5 turns of pencil thick wires (~50 mm2), but with a two cores it is 2+2 turns with pen thick wire (~100 mm2). Thus, for point welding the MOTs are highly welcome.
 

Thread Starter

ConstructionK88

Joined Jul 25, 2018
282
My apologies for being unclear. I'm not using MOTs anymore. I am using large, halide lamp transformer cores. Their secondaries are much much thicker than a mot secondary. Nearly as thick as a mot primary. I'd say one gauge smaller. Well I don't need high volts. About 40 will do. It's simply to jumpstart the arc and the amps carry it. Also it did work just fine with 3mots but I damaged them during rebuild so they didn't last long. The halide transformers are more robust and larger and easier to remove the coils. I live in the US and tombstones are common where I live; lowes, HD, tractor supply, like 15+ welding suppliers in 20 or so miles of me.....they are not cheap sir. Personally owned ones are outdated antiques that nobody wants to sell, for good reason. They last forever. The few I could have bought were in very poor condition.
 

Janis59

Joined Aug 21, 2017
1,894
RE: K88
Just AC welder are giving not so nice sewing. But when one goes to DC plasma, there are enough with 23...25 Volts plus startup-coil giving the short boost. Then it needs much less electricity in comparizon those ugly 380 kg weight russian trafos like mine first ijn 1970 when I stole it for giving to workers two bottles of vodka let them looks in another direction. The main problem with it nowadays was that current spikes was demolishing substation in 3 kilometers radius. Thus Latvenergo warned me if they catch me nexttime I shall pay much. I threw it out and bought a Spanish machine - 180 Amps from 16A network or 100 Amps from 5 Amp fuses - regimes are MAW, TIG, MIG. Just click what want and it weigh a about 5 kilos the cabling includingly. Now I have it about 10 years. Very good obtaining on X-mas price relases for 150 Eur.
 

Thread Starter

ConstructionK88

Joined Jul 25, 2018
282
Probably not the site to admit crimes on but to each their own. My transformers Have 280 wraps on primaries 18AWG solid. 14 on secondaries 10AWG stranded. at 125Vin and roughly 8Vout. Should i reduce primary or secondary or increase secondary? :confused:
 

Thread Starter

ConstructionK88

Joined Jul 25, 2018
282
Im only asking this as i have read previous threads on this site and others on how its not easy to do or wont work but the thing is i have made it work and it would have continued if i wasnt so impatient, dim light, and didnt nick my primaries. Im just trying to replicate what i did a couple days ago.
 

shortbus

Joined Sep 30, 2009
10,050
RE: Shortbus
I have seen. But them are always in series, just in one core one may get a max max 1/2 mm welding on some 5 turns of pencil thick wires (~50 mm2), but with a two cores it is 2+2 turns with pen thick wire (~100 mm2). Thus, for point welding the MOTs are highly welcome.
Can you give a link or picture to one of those? Any welder, even industrial 3Phase SMAW welder transformer I've ever seen has a single core, Possibly more than one winding on that core but still a single core, so all of the magnetics are the same. But I'm willing to learn new ways it can or is done.
 

Thread Starter

ConstructionK88

Joined Jul 25, 2018
282
Spot welding is easy with a mot. Just not going to help me. how can I go about calculating amperage out knowing Vin, amperage available from source, resistance of primaries?, turns, ect...?
 

Thread Starter

ConstructionK88

Joined Jul 25, 2018
282
But that's not what is being discussed.
It isn't but principal is appropriate. I can give better details about what I had, what I did, and performance, but I don't know what I need ask to get the help I'm asking for. Feels like I'm asking an apple tree how to grow oranges.
 

Thread Starter

ConstructionK88

Joined Jul 25, 2018
282

DickCappels

Joined Aug 21, 2008
10,661
I suspect you are using proper eye protection against the UV, but somebody should ask. Are you using proper eye protection? My son in-law has a blind spot in one eye because of a scratch on the lens of his welding mask, and it won't "heal".
 

shortbus

Joined Sep 30, 2009
10,050
My son in-law has a blind spot in one eye because of a scratch on the lens of his welding mask, and it won't "heal".
I have many "floaters" from getting flashed durring arc welding years ago. The old type welding hoods allowed that to happen frequently. I love my new "auto darkening" hoods.
 
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